Integrated fiber array optical switch and method of operation

[0002] This application is related to and filed concurrently with pending U.S. patent application Ser. No. 09/713,869 filed Nov. 15, 2000, entitled “2×2 Integrated Fiber Array Optical Switch and Method of Operation,” pending U.S. patent application Ser. No. 09/713,873 filed Nov. 15, 2000, entitled “Cascaded Integrated Fiber Array Optical Switch and Method of Operation,” and pending U.S. patent application Ser. No. 09/713,924 filed Nov. 15, 2000, entitled “Integrated Fiber Array Optical Switch Using Double-Pass Propagation and Method of Operation.” These applications have been commonly assigned to Optical Switch Corporation.

[0003] This invention relates to the field of total internal reflection devices and more particularly to an integrated fiber array optical switch.

[0004] Fiber-optic communication systems include optical components, such as optical fibers coupled to switching components, that receive, transmit, and otherwise process information in optical signals. The switching components in a fiber-optic communication system selectively direct the information carried by the optical signal to one or more other optical components. A problem with existing fiber-optic communication systems is that they require many complex optical components to perform the switching function. This adds to the cost and size of the fiber-optic communication system. It also leads to slower switching speeds and difficulties with aligning the switching components.

[0005] An integrated fiber array optical switch is provided that substantially eliminates or reduces disadvantages and problems associated with previous optical switches.

[0006] In accordance with one embodiment of the present invention, an optical switch includes an input member, a reflective output member coupled to the input member, and a transmissive output member. The input member supports a plurality of input waveguides, each input waveguide having a reflective surface and operable to receive a corresponding optical signal. The reflective output member supports a plurality of first output waveguides, each first output waveguide coupled to a corresponding input waveguide. The transmissive output member supports a plurality of second output waveguides and has a first position spaced apart from the input member such that the reflective surface of each input waveguide totally internally reflects a corresponding optical signal to a corresponding one of the first output waveguides, and a second position in proximal contact with the input member such that each second output waveguide frustrates the total internal reflection of a corresponding optical signal and receives a corresponding optical signal.

[0007] Another embodiment of the present invention is an optical switch that includes an input member, a reflective output member coupled to the input member, and a transmissive output member. The input member supports a first input waveguide, a second input waveguide, a first output waveguide, and a second output waveguide. The first input waveguide has a reflective surface and receives a first optical signal and the second input waveguide has a reflective surface and receives a second optical signal. The reflective output member supports a first return loop waveguide that couples the first input waveguide to the first output waveguide, and a second return loop waveguide that couples the second input waveguide to the second output waveguide. The transmissive output member supports a third return loop waveguide that couples the first input waveguide to the second output waveguide, and a fourth return loop waveguide that couples the second input waveguide to the first output waveguide.

[0008] The transmissive output member has a first position spaced apart from the input member such that the reflective surface of the first input waveguide totally internally reflects the first optical signal to the first return loop waveguide for communication to the first output waveguide and the reflective surface of the second input waveguide totally internally reflects the second optical signal to the second return loop waveguide for communication to the second output waveguide. The transmissive output member also has a second position in proximal contact with the input member such that the third return loop waveguide frustrates the total internal reflection of the first input waveguide and receives the first optical signal for communication to the second output waveguide and the fourth return loop waveguide frustrates the total internal reflection of the second input waveguide and receives the second optical signal for communication to the first input waveguide.

[0009] Yet another embodiment of the present invention is an optical switch that includes a first input member, a first reflective output member coupled to the first input member, a first transmissive output, a second input member, a second reflective output member coupled to the second input member, and a second transmissive output.

[0010] The first input member supports a first input waveguide having a reflective surface and operable to receive an optical signal. The first reflective output supports a first intermediate waveguide coupled to the first input waveguide. The first transmissive output member supports a second intermediate waveguide and has a first position spaced apart from the input member such that the reflective surface of the input waveguide totally internally reflects the optical signal to the first intermediate waveguide, and a second position in proximal contact with the input member such that the second intermediate waveguide frustrates the total internal reflection of the input waveguide and receives the optical signal.

[0011] The second input member supports the first intermediate waveguide having a reflective surface and the second intermediate waveguide having a reflective surface. The second reflective output member supports a first output waveguide coupled to the first intermediate waveguide and a second output waveguide coupled to the second intermediate waveguide. The second transmissive output member supports a third output waveguide and a fourth output waveguide, and has a first position spaced apart from the second input member and a second position in proximal contact with the second input member.

[0012] Another embodiment of the present invention is an optical switch that includes an input member, a reflective output member coupled to the input member, and a transmissive output member. The input member supports an input waveguide having a reflective surface and operable to receive an optical signal. The reflective output member supports a first output waveguide and a return loop waveguide that is coupled to the input waveguide and the first output waveguide. The transmissive output member supports a second output waveguide and has a first position spaced apart from the input member such that the reflective surface of the input waveguide totally internally reflects the optical signal toward the return loop waveguide for communication to the first output waveguide. The transmissive output member further has a second position in proximal contact with the input waveguide such that the second output waveguide frustrates the total internal reflection of the optical signal and receives the optical signal.

[0013] Technical advantages of the present invention include an optical switch that switches one or more optical signals using waveguides. By using waveguides to guide an optical signal to the switching region and to perform the switching operation, the present invention eliminates the need for costly and sometimes complex optical components. This results in a smaller packing density for the optical switch of the present invention and a more efficient, faster switching operation.

[0014] Another technical advantage provided by the present invention is that the optical switches described herein support an array of input and output waveguides to facilitate the simultaneous switching of multiple channels of an optical switch using a common actuator. Yet another technical advantage provided by the present invention is that by cascading a number of optical switches in a particular arrangement, and by selectively operating each individual optical switch, an N×M optical switch may be constructed.

[0015] While in a switched state, the contact surface of a waveguide is typically placed in proximal contact with a reflective surface of another waveguide to frustrate the total internal reflection of the optical signal. A small portion of the optical signal may be reflected, however, at the reflective surface and processed as though the switch is operating in the unswitched state. This undesired result is one source of a cross-talk signal in the system.

[0016] Another technical advantage provided by the present invention is that the optical switches described herein reduce the effects of a cross-talk signal generated by the above-identified reflection. In particular, the optical switches of the present invention process any cross-talk signals so that a large portion of a cross-talk signal is not received by an optical component of the optical switch. The negative effects of a cross-talk signal are thereby reduced.

[0017] For example, in the switched state, an undesired cross-talk signal resulting from a residual reflection at the FTIR interface between a reflective surface and a contact surface is further processed by a return-loop waveguide to reduce the crosstalk signal intensity. In particular, the crosstalk signal radiation is conveyed by the return-loop waveguide to a second FTIR interface within the output waveguide signal path. In the switched state this second FTIR waveguide interface frustrates the total internal reflection of the crosstalk signal at the reflective surface of the output waveguide. As a result, the small, undesired residual portion of the original optical signal undergoes further reduction in its intensity at this second FTIR interface. Therefore, only a negligible portion of the original optical signal, if any, comprises a crosstalk signal that may actually reach an optical component of the switch. Thus, the crosstalk signal is dissipated and its effects become negligible. This technique is referred to as double-pass propagation. The reduction in the magnitude of the crosstalk signal in the present invention will be referred to as a crosstalk improvement.

[0018] Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.

[0019] For a more complete understanding of the present invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying figures in which like reference numbers indicate like features and wherein:

[0020] FIG. 1 illustrates a 1×2 embodiment of an optical switch in accordance with the present invention;

[0021] FIG. 2A illustrates the 1×2 optical switch operating in an unswitched mode;

[0022] FIG. 2B illustrates the 1×2 optical switch operating in a switched mode;

[0023] FIG. 3 illustrates a 1×8 embodiment of an optical switch in accordance with the present invention;

[0024] FIG. 4 illustrates one embodiment of a switching table that details the operation of the 1×8 optical switch;

[0025] FIG. 5 illustrates a 2×2 embodiment of an optical switch in accordance with the present invention;

[0026] FIG. 6A illustrates the 2×2 optical switch operating in an unswitched mode;

[0027] FIG. 6B illustrates the 2×2 optical switch operating in a switched mode;

[0028] FIG. 7 illustrates another 2×2 embodiment of an optical switch in accordance with the present invention;

[0029] FIG. 8A illustrates the 2×2 optical switch operating in an unswitched mode;

[0030] FIG. 8B illustrates the 2×2 optical switch operating in a switched mode;

[0031] FIG. 9 illustrates yet another 2×2 embodiment of an optical switch in accordance with the present invention;

[0032] FIG. 10A illustrates the 2×2 optical switch operating in an unswitched mode;

[0033] FIG. 10B illustrates the 2×2 optical switch operating in a switched mode;

[0034] FIG. 11 illustrates a 1×2 embodiment of an optical switch using a returned loop waveguide;

[0035] FIG. 12A illustrates the 1×2 optical switch using a return loop waveguide operating in an unswitched mode;

[0036] FIG. 12B illustrates the 1×2 optical switch using a return loop waveguide operating in switched mode;

[0037] FIG. 13 illustrates a 2×2 embodiment of an optical switch using a return loop waveguide;

[0038] FIG. 14A illustrates the 2×2 optical switch using a return loop waveguide operating in an unswitched mode;

[0039] FIG. 14B illustrates the 2×2 optical switch using a return loop waveguide operating in a switched mode; and

[0040] FIG. 15 illustrates a 1×8 embodiment of an optical switch using return loop waveguides.

[0041] FIG. 1 illustrates one embodiment of an optical switch 10 that includes an input member 12 coupled to a baseplate 14, a reflective output member 16 coupled to input member 12, and a transmissive output member 18. Input member 12 supports a plurality of input waveguides 20 and each waveguide 20 may receive and transmit a corresponding optical signal 30. Reflective output member 16 supports a plurality of first output waveguides 22. Each output waveguide 22 is coupled at one end to one end of a corresponding input waveguide 20. Transmissive output member 18 supports a plurality of second output waveguides 24. In general, each input waveguide 20 of optical switch 10 receives an optical signal 30 and selectively communicates the corresponding signal 30 to a corresponding output waveguide 22 and/or output waveguide 24 based upon the position of transmissive output member 18. In this respect, FIG. 1 illustrates a multi-channel 1×2 optical switch 10.

[0042] Input member 12, reflective output member 16, and transmissive output member 18 each comprise a structure made of an appropriate material, such as, for example, silicon, that supports each respective waveguide 20, 22, and 24. Members 12, 16, and 18 may be formed having grooves 26 extending from a first face to a second face of the member 12, 16, and 18. Grooves 26 may comprise V-grooves formed on the surface of a member 12, 16, or 18, or a channel formed within a member 12, 16, or 18. Waveguides 20, 22, and 24 may be positioned in members 12, 16, and 18, respectively, along a corresponding groove 26. In this respect, grooves 26 are used for the precise placement, support, and coupling of the appropriate waveguides 20, 22, and 24. One advantage of members 12, 16, and 18 is that the silicon material can be patterned and implanted to provide a functional electrical circuit for electronic actuation for use in optical switch 10. Another advantage of members 12, 16, and 18 is that they support an array of waveguides 20, 22, and 24 to facilitate the simultaneous switching of multiple channels using a common actuator.

[0043] Waveguides 20, 22, and 24 each comprise an optical waveguide formed by any arrangement of suitable optically transmissive material that communicates optical signal 30 as a guided wave of energy. In one embodiment of switch 10, waveguides 20, 22 and 24 each comprise optical fibers (referred to generally as input optical fibers 20, and output optical fibers 22 and 24). Optical signals 30 comprise visible light, infrared radiation, ultraviolet radiation, or any other suitable optical beam propagating at any suitable wavelength.

[0044] In another embodiment of switch 10, waveguides 20, 22, and 24 each comprise a planar waveguide formed in an appropriate refractive material, such as, for example, silicon dioxide, having a particular index of refraction at a particular wavelength of optical signal 30. The materials used to form waveguides 20-24 in the surrounding refractive materials may be selected to provide particular indices of refraction that are higher than that of the surrounding refractive materials such that waveguides 20-24 communicate signal 30 as a guided wave of energy. In this respect, each of waveguides 202-4 is operable to guide the flow of radiant energy along a path parallel to its axis and to contain the energy of signal 30 within or adjacent to its surface.

[0045] In yet another embodiment of switch 10, a portion of waveguides 20, 22, and 24 comprise optical fibers while the remaining waveguides 20, 22, and 24 comprise planar waveguides to form a hybrid optical fiber/planar waveguide switch 10. For example, waveguides 20 may comprise planar waveguides while waveguides 22 and 24 comprise optical fibers. In another example, a portion of waveguides 20 and corresponding waveguides 22 and 24 comprise planar waveguides, while the remaining portion of waveguides 20 and corresponding waveguides 22 and 24 comprise optical fibers.

[0046] Ribbon array 28 comprises a strip or band made from resin, cloth, plastic, or any other suitable material. In general, any suitable number and combination of waveguides 20, 22, and 24 are bundled in a ribbon array 28 to position, align, or otherwise support waveguides 20, 22, and 24 with relation to members 12, 16, and 18.

[0047] Actuator 34 generally comprises a piezoelectric device, a bimorph transducer, an electromagnetic device, or any other suitable actuation device coupled to transmissive output member 18 that displaces member 18 in response to an electrical, thermal, or otherwise appropriate control signal 36. Activating and deactivating actuator 34 coupled to transmissive output member 18 places member 18 in a selected one of the first or second positions such that waveguides 24 are brought out of or into proximal contact with waveguides 20.

[0048] Aligning rails 38 comprise any suitable structure that aligns members 12, 16, and 18 with respect to each other. In one embodiment, aligning rails 38 comprise any suitable structure, such as, for example, optical fibers or ridges, placed in a channel formed by corresponding V-grooves on the appropriate surfaces of baseplate 14, input member 12, and transmissive output member 18. For example, V-grooves may be formed on a surface of baseplate 14. Corresponding V-grooves may be formed on corresponding surfaces of input member 12 and transmissive output member 18, to form a channel in which the fiber is placed to align members 12, 16, and 18.

[0049] In another example, grooves may be formed on a surface of input member 12 and a surface of transmissive output member 18. A ridge may be formed on the corresponding surface of baseplate 14 to form aligning rails 18. Of course, grooves may also be formed on a surface of baseplate 14 with grooves formed on the corresponding surfaces of members 12 and 18.

[0050] In another embodiment, aligning rails 28 comprise a combination of holes and pins correspondingly formed in input member 12 and output member 18 to control alignment. For example, member 12 may be formed having holes that extend inward from a first face. Member 18 may be formed having pins that extend outward from a first face and that mate with the holes formed in member 12. By appropriately mating the pins of member 18 with the holes of member 12, members 12 and 18 may be aligned. Of course, the holes may also be associated with member 18 and the pins associated with member 12 to accomplish the same alignment.

[0051] In general, aligning rails 38 may be positioned in both the x-axis and y-axis directions to align and/or fix members 12 and 18 with respect to each other and baseplate 14. For example, aligning rails 38 may be used as “tracks” to align transmissive output member 18 with input member 12 as member 18 is actuated between first and second positions on baseplate 14. In another example, aligning rails 38 may be used to fix input member 12 in a particular x-y position with respect to baseplate 14.

[0052] In yet another example, aligning rails 38 may be used to control the range of movement of output member 18. This is accomplished by forming a groove on the surface of member 18 in a direction orthogonal to the direction of movement of member 18. A fiber is then placed in the channel formed by the corresponding grooves of member 18 and baseplate 14. The groove of member 18 has a width that is generally greater than the width of the groove formed on the surface of baseplate 14. In one embodiment, the groove of member 18 is formed wide enough to allow member 18 to travel a predetermined distance before the fiber stops the movement of member 18 at either the first position spaced apart from member 12 or the second position in proximal contact with member 12. The extra width of the groove formed on the surface of member 18 facilitates precision control of the movement of member 18 with respect to input member 12.

[0053] In another embodiment, member 18 is formed with the extra wide groove as discussed above. However, baseplate 14 is formed with a ridge that, in combination with the groove of member 18, controls the movement of member 18 with respect to input member 12. It should be understood that baseplate 14 may be formed with a wider groove than that of member 18 and/or member 18 may be formed with a ridge, to accomplish the same results described above without departing from the scope of the present invention.

[0054] In operation, optical switch 10 communicates each optical signal 30 from an input fiber 20 to a corresponding output optical fiber 22 when transmissive output member 18 is spaced apart from input member 12, as described in greater detail with reference to FIG. 2A. When transmissive output member 18 is placed in proximate contact with input member 12, optical switch 10 communicates each optical signal 30 from an input fiber 20 to a corresponding output optical fiber 24, as described in greater detail with reference to FIG. 2B.

[0055] FIGS. 2A and 2B illustrate in more detail the arrangement of an input optical fiber 20 and the corresponding output optical fibers 22 and 24 of switch 10. Although FIGS. 2A and 2B illustrate an arrangement of a single channel of fibers 20, 22, and 24, switch 10 supports multiple channels of fibers 20, 22, and 24. Each of fibers 20, 22, and 24 includes a core 40 designed to transmit or receive information in the form of light pulses, and a cladding 42 that surrounds core 40 to prevent signal 30 from escaping core 40 during transmission. Each core 40 of optical fibers 20-24 comprises any suitable refractive material, such as glass, having a particular index of refraction. Each cladding 42 of optical fibers 20-24 comprises any suitable refractive material, such as glass, having an index of refraction lower than that of the corresponding core 40 such that signal 30 propagates along the longitudinal axis of an optical fiber 20-24. Optical fibers 20-24 may comprise a multi-mode fiber having a large core (e.g., 50 or 62.5 microns wide) or a single mode fiber having a small core (e.g., 9 microns wide). Although the following description is detailed with reference to fibers 20-24 having a circular cross-section, it should be understood that the cross-section of fibers 20-24 may have any suitable shape, including, but not limited to, an oval or a circle having grooves or notches.

[0056] Input optical fiber 20 comprises reflective surface 43 that forms an interface between fiber 20 and a refractive material 44. Reflective surface 43 of each input optical fiber 20 is at a bias angle with respect to the longitudinal axis of the input optical fiber 20. In general, input member 12 comprises a contact face that is at an angle substantially similar to the bias angle of a reflective surface 43 of an input optical fiber 20. This bias angle may be selected to yield any desired angle of propagation of signal 30 that is totally internally reflected by reflective surface 43. Therefore, although the bias angle of fiber 20 is illustrated as totally internally reflecting signal 30 at a ninety degree angle in FIG. 2A, the bias angle may be selected to totally internally reflect signal 30 at any suitable angle of propagation.

[0057] In one embodiment of switch 10, a portion of cladding 42 of fiber 20 is cleaved, etched, lapped, polished, or otherwise removed to form a notch 46 so that fiber 22 may be positioned in closer proximity to core 40 of fiber 20. Output optical fiber 22 comprises a core 40 that may have an index of refraction substantially similar to that of core 40 of input optical fiber 20. In the embodiment of switch 10 where notch 46 is formed in fiber 20, fiber 22 includes a facet 48 at a bias angle substantially similar to the bias angle of reflective surface 43.

[0058] Output optical fiber 24 comprises a contact surface 50 at an angle that is substantially parallel to the bias angle of reflective surface 43. In general, transmissive output member 18 comprises a contact face that is at an angle substantially similar to the angle of a contact surface 50 of an output optical fiber 24. The contact face of transmissive output member 18 is in proximal contact with the contact face of input member 12 when member 18 is placed in the second position.

[0059] The index of refraction of core 40 of fiber 24 is substantially similar to that of core 40 of fiber 20. Member 18 has a first position spaced apart from member 12 and a second position in proximal contact with member 12. In conjunction with member 18, fiber 24 has a first position spaced apart from fiber 20 and a second position in proximal contact with fiber 20 to frustrate the total internal reflection of optical signal 30. The term “proximal contact” refers not only to direct contact between optical fibers 24 and 20, but also contemplates any spacing or partial contact between fibers to frustrate the total internal reflection of optical signal 30 to a desired degree. By controllably varying the spacing between fibers 24 and 20 to a desired degree, optical switch 10 may perform a beam splitting or variable attenuation operation such that a desired portion of signal 30 is communicated to fiber 22 and the remaining portion of the signal 30 is communicated to fiber 24. In one embodiment, reflective surface 43 of fiber 20 is substantially parallel to contact surface 50 of fiber 24 when fiber 24 is placed in proximal contact with fiber 20 such that the longitudinal axis of fiber 20 is substantially aligned with the longitudinal axis of fiber 24.

[0060] Refractive material 44 comprises air or any other suitable substance that has an index of refraction lower than that of core 40 of optical fiber 20. Optical signal 30 contacts reflective surface 43 at an input angle. If the input angle at which signal 30 contacts reflective surface 43 is equal to or above a critical angle of refraction associated with the interface between core 40 of fiber 20 and refractive material 44, then reflective surface 43 totally internally reflects optical signal 30 at an output angle that is generally determined based upon the input angle of signal 30. Reflective surface 43 of fiber 20 therefore reflects optical signal 30 by total internal reflection (TIR).

[0061] In operation of optical switch 10 with transmissive output member 18 spaced apart from input member 12 and, therefore, output fiber 24 spaced apart from input fiber 20, as illustrated in FIG. 2A, fiber 20 communicates optical signal 30 through core 40 as indicated by arrow 52. Total internal reflection at reflective surface 43, the interface between core 40 of fiber 20 and refractive material 44, directs signal 30 through cladding 42 of fiber 20 and into core 40 of output optical fiber 22, as indicated by arrow 54. By placing output optical fiber 22 closer to core 40 of input optical fiber 20 using notch 46 of fiber 20 and facet 48 of fiber 22, switch 10 reduces the amount of cladding 42 through which optical signal 30 propagates from core 40 of fiber 20 to core 40 of fiber 22. In this respect, switch 10 reduces the divergence and, therefore, the insertion loss of optical signal 30. Moreover, switch 10 reduces any “lensing” effects.

[0062] Transmissive output member 18 is placed in proximal contact with input member 12 such that contact surface 50 of fiber 24 is placed in proximal contact with reflective surface 43 of fiber 20. In operation of switch 10 with output optical fiber 24 placed in proximal contact with input optical fiber 20, as illustrated in FIG. 2B, fiber 20 communicates optical signal 30 through core 40 as indicated by arrow 52. Core 40 of fiber 24 having an index of refraction substantially similar to core 40 of fiber 20, frustrates the total internal reflection of optical signal 30 at reflective surface 43. As a result, core 40 of fiber 24 receives optical signal 30 from core 40 of fiber 20. Optical signal 30 propagates through fiber 24 in a direction indicated by arrow 56. Therefore, FIGS. 2A and 2B together illustrate the operation of switch 10 with fiber 24 spaced apart from fiber 20 and with fiber 24 placed in proximal contact with fiber 20, respectively.

[0063] By using members 12, 16, and 18 to support an array of waveguides 20, 22, and 24 during the switching operation, switch 10 facilitates the simultaneous switching of multiple channels. In this respect, optical switch 10 comprises an N-channel 1×2 optical switch.

[0064] FIG. 3 illustrates one embodiment of an optical switch 100 that includes optical switches 10a,10b,and 10carranged in a cascaded architecture to form a 1×8 optical switch. Optical switch 10aincludes an input member 12, a reflective output member 16, and a transmissive output member 18. Input member 12 of switch 10asupports an input fiber 20. Reflective output member 16asupports output fiber 22a.Transmissive output member 18asupports output fiber 24a.As switch 10aincludes one input channel and two output channels, switch 10acomprises a 1×2 optical switch.

[0065] Input member 12bof switch 10breceives output fibers 22aand 24aof switch 10aas input fibers for switch 10b.In this respect, output fibers 22aand 24acomprise intermediate optical fibers for switch 100. Reflective output member 16bsupports output fibers 22band transmissive output member 18bsupports output fibers 24b.As switch 10bincludes two input channels and four output channels, switch 10bcomprises a multi-channel 1×2 optical switch. In this respect, the combination of switches 10aand 10bcomprises a 1×4 optical switch.

[0066] Input member 12creceives output fibers 22band 24bas input fibers to switch 10c.In this respect, output fibers 22band 24bcomprise intermediate optical fibers for switch 100. Reflective output member 16csupports four output fibers 22cand transmissive output member 18csupports four output fibers 24c.As switch 10cincludes four input channels and eight output channels, switch 10ccomprises a multi-channel 1×2, optical switch. The combination of switches 10a,10b,and 10ctherefore comprises a 1×8 optical switch. Although optical switch 100 is illustrated having optical switches 10a,10b,and 10carranged to form a 1×8 optical switch, it should be understood that optical switch 100 may include any number and combination of optical switches 10 appropriately arranged to form a 1×N optical switch.

[0067] The operation of switch 100 illustrated in FIG. 3 is described with reference to the switch states illustrated in switching table 150 of FIG. 4. Referring to FIG. 4, table 150 includes columns 152, 154, and 156 that identify the states of switches 10a,10b,and 10c,respectively. As illustrated in switching table 150, a particular switch 10 may be in an “OFF” state or an “ON” state. When a switch 10 is in the “OFF” state, the transmissive output member 18 of the switch 10 is in the first position spaced apart from the input member 12 of the switch 10. When a switch 10 is in the “ON” state, the transmissive output member 18 is in the second position in proximal contact with the input member 12 of the switch 10. Table 150 further includes column 158 that identifies the output channel of an optical signal 30 for any given operation of switches 10a,10b,and 10c,as identified in rows 160-174.

[0068] Referring to row 160, switches 10a,10b,and 10care each in the “OFF” state. In this regard, transmissive output member 18ais spaced apart from input member 12a.Input fiber 20 communicates optical signal 30. Total internal reflection at reflective surface 43 of input fiber 20 directs signal 30 to output fiber 22awhich is the second input channel for input member 12b.With switch 10bin the “OFF” state, transmissive output member 18bis spaced apart from input member 12b.Therefore, total internal reflection at reflective surface 43 of fiber 22adirects signal 30 to the output fiber 22bthat enters the fourth input channel of input member 12c.With switch 10cin the “OFF” state, transmissive output member 18cis spaced apart from input member 12c.Therefore, total internal reflection at reflective surface 43 of the appropriate fiber 22bdirects signal 30 to the output fiber 22cthat is the eighth output channel of switch 10c.

[0069] Referring to row 162, switches 10aand 10bare in the “OFF” state and 10cis in the “ON” state. In this regard, transmissive output member 18ais spaced apart from input member 12a.Input fiber 20 communicates optical signal 30. Total internal reflection at reflective surface 43 of input fiber 20 directs signal 30 to output fiber 22awhich is the second input channel for input member 12b.With switch 10bin the “OFF” state, transmissive output member 18bis spaced apart from input member 12b.Therefore, total internal reflection at reflective surface 43 of fiber 22adirects signal 30 to the output fiber 22bthat enters the fourth input channel of input member 12c.With switch 10cin the “ON” state, transmissive output member 18cis placed in proximal contact with input member 12c.Therefore, an appropriate output fiber 24cfrustrates the total internal reflection of optical signal 30 at reflective surface 43 of the fiber 22b.As a result, the output fiber 24cthat is the fourth output channel of switch 10creceives optical signal 30.

[0070] Referring to row 164, switches 10aand 10care each in the “OFF” state and switch 10bis in the “ON” state. In this regard, transmissive output member 18ais spaced apart from input member 12a.Input fiber 20 communicates optical signal 30. Total internal reflection at reflective surface 43 of input fiber 20 directs signal 30 to output fiber 22awhich is the second input channel for input member 12b.With switch 10bin the “ON” state, transmissive output member 18bis placed in proximal contact with input member 12b.Therefore, an appropriate output fiber 24bfrustrates the total internal reflection of optical signal 30 at reflective surface 43 of fiber 22a.As a result, fiber 24breceives optical signal 30 and enters the second channel of input member 12c.With switch 10cin the “OFF” state, transmissive output member 18cis spaced apart from input member 12c.Therefore, total internal reflection at reflective surface 43 of the appropriate fiber 24bdirects signal 30 to the output fiber 22cthat is the sixth output channel of switch 10c.

[0071] Referring to row 166, switch 10ais in the “OFF” state and switches 10band 10care each in the “ON” state. In this regard, transmissive output member 18ais spaced apart from input member 12a.Input fiber 20 communicates optical signal 30. Total internal reflection at reflective surface 43 of input fiber 20 directs signal 30 to output fiber 22awhich is the second input channel for input member 12b.With switch 10bin the “ON” state, transmissive output member 18bis placed in proximal contact with input member 12b.Therefore, an appropriate output fiber 24bfrustrates the total internal reflection of optical signal 30 at reflective surface 43 of fiber 22a.As a result, fiber 24breceives optical signal 30 and enters the second channel of input member 12c.With switch 10cin the “ON” state, transmissive output member 18cis placed in proximal contact with input member 12c.Therefore, an appropriate output fiber 24cfrustrates the total internal reflection of optical signal 30 at reflective surface 43 of the fiber 24b.As a result, the output fiber 24cthat is the second output channel of switch 10creceives optical signal 30.

[0072] Referring to row 168, switch 10ais in the “ON” state and switches 10band 10care each in the “OFF” state. In this regard, transmissive output member 18ais placed in proximal contact with input member 12a.Fiber 20 communicates optical signal 30. Fiber 24afrustrates the total internal reflection of optical signal 30 at reflective surface 43 of fiber 20. As a result, fiber 24areceives optical signal 30 and enters the first channel of input member 12b.With switch 10bin the “OFF” state, transmissive output member 18bis spaced apart from input member 12b.Therefore, total internal reflection at reflective surface 43 of fiber 24adirects signal 30 to the output fiber 22bthat enters the third input channel of input member 12c.With switch 10cin the “OFF” state, transmissive output member 18cis spaced apart from input member 12c.Therefore, total internal reflection at reflective surface 43 of the appropriate fiber 22bdirects signal 30 to the output fiber 22cthat is the seventh output channel of switch 10c.

[0073] Referring to row 170, switches 10aand 10care in the “ON” state and switch 10bis in the “OFF” state. In this regard, transmissive output member 18ais placed in proximal contact with input member 12a.Fiber 20 communicates optical signal 30. Fiber 24afrustrates the total internal reflection of optical signal 30 at reflective surface 43 of fiber 20. As a result, fiber 24areceives optical signal 30 and enters the first channel of input member 12b.With switch 10bin the “OFF” state, transmissive output member 18bis spaced apart from input member 12b.Therefore, total internal reflection at reflective surface 43 of fiber 24adirects signal 30 to the output fiber 22bthat enters the third input channel of input member 12c.With switch 10cin the “ON” state, transmissive output member 18cis placed in proximal contact with input member 12c.Therefore, an appropriate output fiber 24cfrustrates the total internal reflection of optical signal 30 at reflective surface 43 of the fiber 22b.As a result, the output fiber 24cthat is the third output channel of switch 10creceives optical signal 30.

[0074] Referring to row 172, switches 10aand 10bare in the “ON” state and switch 10cis in the “OFF” state. In this regard, transmissive output member 18ais placed in proximal contact with input member 12a.Fiber 20 communicates optical signal 30. Fiber 24afrustrates the total internal reflection of optical signal 30 at reflective surface 43 of fiber 20. As a result, fiber 24areceives optical signal 30 and enters the first channel of input member 12b.With switch 10bin the “ON” state, transmissive output member 18bis placed in proximal contact with input member 12b.Therefore, an appropriate output fiber 24bfrustrates the total internal reflection of optical signal 30 at reflective surface 43 of fiber 24a.As a result, fiber 24breceives optical signal 30 and enters the first channel of input member 12c.With switch 10cin the “OFF” state, transmissive output member 18cis spaced apart from input member 12c.Therefore, total internal reflection at reflective surface 43 of the appropriate fiber 24bdirects signal 30 to the output fiber 22cthat is the fifth output channel of switch 10c.

[0075] Referring to row 174, switches 10a,10b,and 10care each in the “ON” state. In this regard, transmissive output member 18ais placed in proximal contact with input member 12a.Fiber 20 communicates optical signal 30. Fiber 24afrustrates the total internal reflection of optical signal 30 at reflective surface 43 of fiber 20. As a result, fiber 24areceives optical signal 30 and enters the first channel of input member 12b.With switch 10bin the “ON” state, transmissive output member 18bis placed in proximal contact with input member 12b.Therefore, an appropriate output fiber 24bfrustrates the total internal reflection of optical signal 30 at reflective surface 43 of fiber 24a.As a result, fiber 24breceives optical signal 30 and enters the first channel of input member 12c.With switch 10cin the “ON” state, transmissive output member 18cis placed in proximal contact with input member 12c.Therefore, an appropriate output fiber 24cfrustrates the total internal reflection of optical signal 30 at reflective surface 43 of the fiber 24b.As a result, the output fiber 24cthat is the first output channel of switch 10creceives optical signal 30.

[0076] FIG. 5 illustrates one embodiment of a 2×2 optical switch 200 that includes input member 12 coupled to baseplate 14, reflective output member 16 coupled to input member 12, and transmissive output member 18 having a first position spaced apart from input member 12 and a second position in proximal contact with input member 12. Input member 12 supports input waveguides 202aand 202bas well as output waveguides 204aand 204b.Reflective output member 16 supports a first return loop waveguide 206athat couples waveguide 202ato waveguide 204a,and a second return loop waveguide 206bthat couples waveguide 202bto waveguide 204b.Transmissive output member 18 supports a third return loop waveguide 206cthat couples waveguide 202ato waveguide 204b,and a fourth return loop waveguide 206dthat couples waveguide 202bto waveguide 204a.

[0077] Waveguides 202a-b,204a-b,and 206a-deach comprise an optical waveguide formed by an arrangement of suitable optically transmissive material that communicates optical signal 30 as a guided wave of energy. In one embodiment of switch 200, waveguides 202a-b,204a-b,and 206a-deach comprise optical fibers (referred to generally as fibers 202a-b,204a-b,and 206a-d). In general, fibers 202a-b, 204a-b,and 206a-deach include a core 40 and a cladding 42, as described above with regard to fibers 20-24. In addition, fibers 202a-band 204a-binclude a reflective surface 43 and fibers 206a-dinclude a contact surface 50, as described above with regard to fibers 20-24. In another embodiment of switch 200, waveguides 202a-b,204a-b,and 206a-deach comprise a planar waveguide formed in an appropriate refractive material, as described above with regard to waveguides 20-24. In yet another embodiment, waveguides 202a-b,204a-b,and 206a-deach comprise an optical fiber and/or a planar waveguide, as described above with regard to waveguides 20-24, to form a hybrid optical fiber/planar waveguide optical switch 200.

[0078] In operation, each of input fibers 202aand 202bcommunicates a corresponding optical signal 30 to a selected one of output optical fibers 204aor 204bbased upon the position of transmissive output member 18. For example, optical switch 200 communicates optical signal 30afrom input optical fiber 202ato output optical fiber 204a,and input optical signal 30bfrom input optical fiber 202bto output optical fiber 204b,when transmissive output member 18 is spaced apart from input member 12, as described in greater detail with reference to FIG. 6A. Optical switch 200 communicates optical signal 30afrom input optical fiber 202ato output optical fiber 204b,and optical signal 30bfrom input optical fiber 202bto output optical fiber 204awhen transmissive output member 18 is placed in proximal contact with input member 12, as described in greater detail with reference to FIG. 6B.

[0079] In operation of optical switch 200 with return loop fibers 206cand 206dspaced apart from input optical fibers 202aand 202b,as illustrated in FIG. 6A, fibers 202aand 202bcommunicate optical signals 30aand 30b,respectively. Total internal reflection at reflective surface 43 of input fiber 202adirects optical signal 30ato output optical fiber 204avia return loop fiber 206a.Total internal reflection at reflective surface 43 of input optical fiber 202bdirects optical signal 30bto output optical fiber 204bvia return loop fiber 206b.

[0080] In operation of optical switch 200 with return loop fibers 206cand 206din proximal contact with input fibers 202aand 202b,as illustrated in FIG. 6B, fibers 202aand 202bcommunicate optical signals 30aand 30b,respectively. Return loop fiber 206cfrustrates the total internal reflection of optical signal 30aat reflective surface 43 of input optical fiber 202a.As a result, return loop fiber 206creceives optical signal 30aand communicates signal 30ato output optical fiber 204b.Return loop fiber 206dfrustrates the total internal reflection of optical signal 30bat reflective surface 43 of input fiber 202b.As a result, return loop fiber 206dreceives optical signal 30band communicates signal 30bto output optical fiber 204a.Therefore, FIGS. 6A and 6B together illustrate the operation of switch 200 with fibers 206cand 206dspaced apart from fibers 202aand 202b,respectively, and with fibers 206cand 206dplaced in proximal contact with fibers 202aand 202b,respectively.

[0081] FIG. 7 illustrates one embodiment of a 2×2 optical switch 300 that includes first input member 12acoupled to baseplate 14a,first reflective output member 16acoupled to input member 12a,and first transmissive output member 18ahaving a first position spaced apart from input member 12aand a second position in proximal contact with input member 12a.First input member 12asupports input waveguides 302aand 302b.First reflective output member 16asupports a first intermediate waveguide 306a,and a second intermediate waveguide 306b,also referred to as return-loop waveguides 306aand 306b.Transmissive output member 18asupports a third intermediate waveguide 306c,and a fourth intermediate waveguide 306d,also referred to as return-loop waveguides 306cand 306d.

[0082] Optical switch 300 further includes a second input member 12bcoupled to a baseplate 14b,a second reflective output member 16bcoupled to input member 12b,and a second transmissive output member 18bhaving a first position spaced apart from input member 12 and a second position placed in proximal contact with input member 12b.Input member 12bsupports output waveguides 304aand 304b.Reflective output member 16bsupports intermediate waveguides 306cand 306dreceived from transmissive output member 18a.Transmissive output member 18bsupports intermediate waveguides 306aand 306breceived from reflective output member 16a.

[0083] Waveguides 302a-b,304a-b,and 306a-deach comprise an optical waveguide formed by an arrangement of suitable optically transmissive material that communicates optical signal 30 as a guided wave of energy. In one embodiment of switch 300, waveguides 302a-b,304a-b,and 306a-deach comprise optical fibers (referred to generally as fibers 302a-b,304a-b,and 306a-d,respectively) . In general, fibers 302a-b,304a-b,and 306a-deach include a core 40 and a cladding 42, as described above with regard to fibers 20-24. In addition, fibers 302a-band 304a-binclude a reflective surface 43 and fibers 306a-dinclude a contact surface 50, as described above with regard to fibers 20-24. In another embodiment of switch 300, waveguides 302a-b,304a-b,and 306a-deach comprise a planar waveguide formed in an appropriate refractive material, as described above with regard to waveguides 20-24. In yet another embodiment, waveguides 302a-b,304a-b,and 306a-deach comprise an optical fiber and/or a planar waveguide, as described above with regard to waveguides 20-24, to form a hybrid optical fiber/planar waveguide optical switch 300.

[0084] In operation, each of input fibers 302aand 302bcommunicates a corresponding optical signal 30 to a selected one of output optical fibers 304aor 304bbased upon the position of transmissive output members 18aand 18b.For example, optical switch 300 communicates optical signal 30afrom input optical fiber 302ato output optical fiber 304a,and input optical signal 30bfrom input optical fiber 302bto output optical fiber 304b,when transmissive output member 18ais spaced apart from input member 12aand transmissive output member 18bis placed in proximal contact with input member 12b,as described in greater detail with reference to FIG. 8A. Optical switch 300 communicates optical signal 30afrom input optical fiber 302ato output fiber 304b,and optical signal 30bfrom input optical fiber 302bto output fiber 304awhen transmissive output member 18ais placed in proximal contact with input member 12aand transmissive output member 18bis spaced apart from input member 12b,as described in greater detail with reference to FIG. 8B.

[0085] In operation of optical switch 300 with intermediate fibers 306cand 306dspaced apart from input optical fibers 302aand 302b,and intermediate fibers 306aand 306bplaced in proximal contact with output fibers 304aand 304b,respectively, as illustrated in FIG. 8A, fibers 302aand 302bcommunicate optical signals 30aand 30b,respectively. Total internal reflection at reflective surface 43 of input fiber 302adirects optical signal 30ato output optical fiber 304avia intermediate fiber 306a.Total internal reflection at reflective surface 43 of input optical fiber 302bdirects optical signal 30bto output optical fiber 304bvia intermediate fiber 306b.

[0086] In operation of optical switch 300 with intermediate fibers 306cand 306din proximal contact with input fibers 302aand 302b,and intermediate fibers 306aand 306bspaced apart from fibers 304aand 304b,as illustrated in FIG. 8B, fibers 302aand 302bcommunicate optical signals 30aand 30b,respectively. Intermediate fiber 306cfrustrates the total internal reflection of optical signal 30aat reflective surface 43 of input optical fiber 302a.As a result, intermediate fiber 306creceives optical signal 30aand communicates signal 30ato output optical fiber 304bdue to total internal reflection at reflective surface 43 of fiber 304b.Intermediate fiber 306dfrustrates the total internal reflection of optical signal 30bat reflective surface 43 of input fiber 302b.As a result, intermediate fiber 306dreceives optical signal 30band communicates signal 30bto output optical fiber 304adue to total internal reflection at reflective surface 43 of fiber 304a.Therefore, FIGS. 8A and 8B together illustrate the operation of switch 300.

[0087] FIG. 9 illustrates one embodiment of a 2×2 optical switch 400 that includes first input member 12acoupled to first reflective output member 16a,and second input member 12bcoupled to second reflective output member 16b.Second reflective output member 16bhas a first position spaced apart from first input member 12aand a second position in proximal contact with first input member 12a.First input member 12asupports input waveguide 402a.First reflective output member 16asupports first output waveguide 404a.Second input member 12bsupports second input waveguide 402b.Second reflective output member 16bsupports second output waveguide 404b.

[0088] Waveguides 402a-band 404a-beach comprise an optical waveguide formed by an arrangement of suitable optically transmissive material that communicates optical signal 30 as a guided wave of energy. In one embodiment of switch 400, waveguides 402a-band 404a-beach comprise optical fibers (referred to generally as fibers 402a-band 404a-b). In general, fibers 402a-band 404a-beach include a core 40 and a cladding 42, as described above with regard to fibers 20-24. In addition, fiber 402aincludes a reflective surface 43 and fiber 404bincludes a contact surface 50, as described above with regard to fibers 20-24. In another embodiment of switch 400, waveguides 402a-band 404a-beach comprise a planar waveguide formed in an appropriate refractive material, as described above with regard to waveguides 20-24. In yet another embodiment, waveguides 402a-band 404a-beach comprise an optical fiber and/or a planar waveguide, as described above with regard to waveguides 20-24, to form a hybrid optical fiber/planar waveguide optical switch 400.

[0089] In operation, each of input fibers 402aand 402bcommunicates a corresponding optical signal 30 to a selected one of output optical fibers 404aor 404bbased upon the position of second reflective output member 16b.For example, optical switch 400 communicates optical signal 30afrom input optical fiber 402ato output optical fiber 404a,and input optical signal 30bfrom input optical fiber 402bto output optical fiber 404b,when second reflective output member 16bis spaced apart from first input member 12a,as described in greater detail with reference to FIG. 10A. Optical switch 400 communicates optical signal 30afrom input optical fiber 402ato output optical fiber 404b,and optical signal 30bfrom input optical fiber 402bto output optical fiber 404awhen second reflective output member 16bis placed in proximal contact with first input member 12a,as described in greater detail with reference to FIG. 10B.

[0090] In operation of optical switch 400 with output fiber 404bspaced apart from input fiber 402a,as illustrated in FIG. 10A, fibers 402aand 402bcommunicate optical signals 30aand 30b,respectively. Total internal reflection at reflective surface 43 of input fiber 402adirects optical signal 30ato output fiber 404a.Total internal reflection at contact surface 50 of output fiber 404bdirects optical signal 30bto fiber 404b.

[0091] In operation of optical switch 400 with fiber 404bplaced in proximal contact with fiber 402a,as illustrated in FIG. 10B, fibers 402aand 402bcommunicate optical signals 30aand 30b,respectively. Fiber 404bfrustrates the total internal reflection of optical signal 30aat reflective surface 43 of input fiber 402a.As a result, output fiber 404breceives optical signal 30a.Input fiber 402afrustrates the total internal reflection of optical signal 30bat contact surface 50 of output fiber 404b.As a result, output fiber 404areceives optical signal 30b.Therefore, FIGS. 10A and 10B together illustrate the operation of switch 400.

[0092] FIG. 11 illustrates one embodiment of a 1×2 optical switch 500 that includes input member 12, reflective output member 16 coupled to input member 12, and transmissive output member 18 having a first position spaced apart from input member 12 and a second position in proximal contact with input member 12. Input member 12 supports input waveguide 502. Reflective output member 16 supports first output waveguide 504aand a return loop waveguide 506. Transmissive output member 18 supports a second output waveguide 504b,and a switching waveguide 508.

[0093] Waveguides 502, 504a-b,506, and 508 each comprise an optical waveguide formed by an arrangement of suitable optically transmissive material that communicates optical signal 30 as a guided wave of energy. In one embodiment of switch 500, waveguides 502, 504a-b,506, and 508 each comprise optical fibers (referred to generally as fibers 502, 504a-b,506 and 508, respectively) . In general, fibers 502, 504a-b,506, and 508 each include a core 40 and a cladding 42, as described above with regard to fibers 20-24. In addition, fibers 502 and 506 include a reflective surface 43 and fibers 504band 508 include a contact surface 50, as described above with regard to fibers 20-24. In another embodiment, fiber 506 includes a reflective surface 43 that operates in conjunction with contact surface 50 of fiber 504b,and fiber 504aincludes a reflective surface 43 that operates in conjunction with fiber 508. In another embodiment of switch 500, waveguides 502, 504a-b,506 and 508 each comprise a planar waveguide formed in an appropriate refractive material, as described above with regard to waveguides 20-24. In yet another embodiment, waveguides 502, 504a-b,and 506, and 508 each comprise an optical fiber and/or a planar waveguide, as described above with regard to waveguides 20-24, to form a hybrid optical fiber/planar waveguide optical switch 500.

[0094] In operation, input fiber 502 communicates an optical signal 30 to a selected one of output optical fibers 504aor 504bbased upon the position of transmissive output number 18a.A technical advantage provided by the present invention is that the optical switch 500 reduces the effects of cross-talk signals. For example, while transmissive output member 18 is placed in proximal contact with input member 12, the contact surface 50 of output fiber 504bis placed in proximal contact with reflective surface 43 of input fiber 502 to frustrate the total internal reflection of optical signal 30. A small portion of optical signal 30 may be reflected, however, at reflective surface 43 and processed as though optical switch 500 is operating in the unswitched state. This undesired result is one source of a cross-talk signal in the system. Optical switch 500 uses double-pass propagation to process any such cross-talk signals so that a large portion of the cross-talk signals is not received by an optical component, such as output fiber 504a,of optical switch 500. The negative effects of a cross-talk signal are thereby reduced.

[0095] FIG. 12A illustrates optical switch 500 with output optical fiber 504band switching fiber 508 spaced apart from input fiber 502 and output fiber 504a,respectively. In operation, input fiber 502 communicates optical signal 30. Total internal reflection at reflective surface 43 of input fiber 502 directs optical signal 30 to return loop fiber 506. Total internal reflection at reflective surface 43 of return loop fiber 506 directs optical signal 30 to output fiber 504a.

[0096] FIG. 12B illustrates optical switch 500 with output fiber 504band switching fiber 508 placed in proximal contract with input fiber 502 and output fiber 504a,respectively. In operation, input fiber 502 communicates optical signal 30. Contact surface 50 of output optical fiber 504bfrustrates the total internal reflection of optical signal 30 at reflective surface 43 of input fiber 502. As a result, output optical fiber 504breceives almost all of signal 30. Ideally, contact surface 50 of fiber 504bfrustrates the total internal refection of the entire signal 30 at reflective surface 43 such that signal 30 is communicated into fiber 504b,as illustrated using a solid line for signal 30. Reflection of a small, residual portion of signal 30 at the interface between surfaces 43 and 50 may result in a cross-talk signal 510, as illustrated using a dashed line. A technical advantage provided by switch 500 illustrated in FIGS. 11, 12A and 12B is that switch 500 minimizes the amount of cross-talk signal 510 that is received by fiber 504a,or any other optical component of switch 500.

[0097] Referring to FIG. 12B, return loop optical fiber 506 propagates cross-talk signal 510 toward a reflective surface 43. Switching fiber 508 frustrates the total internal reflection of cross-talk signal 510 at reflective surface 43 of return loop fiber 506. This technique may be referred to as double-pass propagation because cross-talk signal 510 is subjected to a second FTIR interface. Only a negligible residual portion of cross-talk signal 510, if any, is directed by total internal reflection into fiber 504a.Almost all of cross-talk signal 510 is directed away from any of the optical components of switch 500. Therefore, switch 500 reduces the effects of cross-talk signal 510 and results in what is generally referred to as a cross-talk improvement.

[0098] FIG. 13 illustrates one embodiment of a 2×2 optical switch 600 that includes a first input member 12acoupled to a first reflective output member 16a,and a second input member 12bcoupled to a second reflective output member 16b.Second input member 12bhas a first position spaced apart from the first input member 12aand a second position in proximal contact with first input member 12a.First input member 12asupports first input waveguide 602aand second output waveguide 604b.Second input member 12bsupports second input waveguide 602band first output waveguide 604a.First reflective output member 16asupports first return loop waveguide 606a.Second reflective output member 16bsupports second return loop waveguide 606b.

[0099] Waveguides 602a-b,604a-band 606a-beach comprise an optical waveguide formed by an arrangement of suitable optically transmissive material that communicates optical signal 30 as a guided wave of energy. In one embodiment of switch 600, waveguides 602a-b,604a-b,and 606a-beach comprise optical fibers (referred to generally as fibers 602a-b,604a-b,and 606a-b). In general, fibers 602a-b,604a-b,and 606a-beach includes a core 40 and a cladding 42, as described about with regard to fibers 20-24. In addition, fibers 602aand 604binclude a reflective surface 43 and fibers 602band 604ainclude a contact surface 50, as described above with regard to fibers 20-24. In another embodiment of switch 600, waveguides 602a-b,604a-b,and 606a-beach comprise a planar waveguide formed in an appropriate refractive material, as described above with regard to waveguides 20-24. In yet another embodiment, waveguides 602a-b,604a-b,and 606a-beach comprise an optical fiber and/or a planar waveguide, as described above with regard to waveguides 20-24, to form a hybrid optical fiber/planar waveguide optical switch 600.

[0100] In operation, each of input fibers 602aand 602bcommunicates a corresponding optical signal 30 to a selected one of output optical fibers 604aor 604bbased upon the position of second input member 12b.For example, optical switch 600 communicates optical. signal 30afrom input optical fiber 602ato output optical fiber 604b,and input optical signal 30bfrom input optical fiber 602bto output optical fiber 604a,when second input member 12bis spaced apart from first input member 12a,as described in greater detail with reference to FIG. 14A. Optical switch 600 communicates optical signal 30afrom input optical fiber 602ato output optical fiber 604a,and optical signal 30bfrom input optical fiber 602bto output optical fiber 604bwhen second input member 12bin placed in proximal contact with first input member 12a,as described in greater detail with reference to FIG. 14B.

[0101] In operation of optical switch 600 with output fiber 604aand input fiber 602bin proximal contact with input fiber 602aand output fiber 604b,respectively, as illustrated in FIG. 14A, fibers 602aand 602bcommunicate optical signals 30aand 30b,respectively. Total internal reflection at reflective surface 43 of input fiber 602adirects optical signal 30ato return loop fiber 606a.Total internal reflection at reflective surface 43 of fiber 604bdirects signal 30ainto output fiber 604b.Input fiber 602bcommunicates optical signal 30b.Total internal reflection at contact surface 50 of fiber 602bdirects signal 30bto return loop optical fiber 606b.Return loop fiber 606bpropagates optical signal 30btoward contact surface 50 of input fiber 604a.Total internal reflection of signal 30bat contact surface 50 of fiber 604adirects signal 30binto fiber 604a.In this respect, input fiber 602 communicates optical signal 30ato output fiber 604b.Furthermore, input fiber 602bcommunicates optical signal 30bto output fiber 604a.

[0102] In operation of switch 600 with fibers 604aand 602bin proximal contact with fibers 602aand 604b,respectively, as illustrated in FIG. 14B, fibers 602aand 602bcommunicate optical signal 30aand 30b,respectively. Contact surface 50 of fiber 604afrustrates the total internal reflection of optical signal 30aat reflective surface 43 of input fiber 602a.As a result, fiber 604areceives almost all of signal 30a.Similarly, fiber 604breceives almost all of optical signal 30bas a result of frustrated total internal reflection of signal 30bat contact surface 50 of fiber 602b.Signals 30aand 30bare indicated using solid lines.

[0103] As described above with reference to cross-talk signal 510 in FIGS. 12A and 12B, reflection of a small, residual portion of signals 30aand 30bat the interfaces between fibers 604aand 602a,and fibers 604band 602b,respectively, results in cross-talk signals 610 and 612. Cross-talk signals 610 and 612 are indicated using dashed lines. A particular advantage provided by switch 600 illustrated in FIGS. 14A and 14B is that switch 600 further processes cross-talk signals 610 and 612 so that a large portion of cross-talk signals 610 and 612 are not received by output fibers 604aand 604b.

[0104] Referring to FIG. 14B, return loop fiber 606apropagates signal 610 toward reflective surface 43 of fiber 604b.Contact surface 50 of fiber 602bfrustrates the total internal reflection of signal 610 such that signal 610 propagates to return loop fiber 606b.Similarly, return loop fiber 606bpropagates signal 612 toward contact surface 50 of fiber 604a.Reflective surface 43 of fiber 602afrustrates the total internal reflection of signal 612 such that signal 612 propagates to return loop fiber 606a.Only a negligible residual portion of signals 610 and 612, if any, is directed by reflection into fibers 604aand 604b.In this respect, return loop fibers 606aand 606bpropagate cross-talk signals 610 and 612 until they dissipate. Therefore, switch 600 reduces the effects of cross-talk signals 610 and 612.

[0105] FIG. 15 illustrates a 1×8 embodiment of an optical switch 700 that uses return loop waveguides to achieve a cross-talk improvement using double-pass propagation. Optical switch 700 includes optical switches 500a,500b,and 500carranged in a cascaded architecture. Each individual optical switch 500a-cuses one or more return loop waveguides 506, as described in detail with regard to FIGS. 11, 12A and 12B, to achieve a cross-talk improvement using double-pass propagation. Although optical switch 500 is described as a single channel 1×2 optical switch with reference to FIGS. 11, 12A, and 12B, it should be understood that switches 500band 500cof switch 700 comprise multi-channel 1×2 optical switches.

[0106] The operation of switch 700 follows the operation of switch 100 described with reference to FIGS. 3 and 4. In particular, if switches 500a,500b,and 500coperate in the appropriate switched or unswitched states described in columns 152, 154, and 156, respectively, of table 150 illustrated in FIG. 4, then the appropriate output channel among output channels 504aand 504b,receives optical signal 30, as described in column 158 of table 150. A technical advantage of the present invention is that optical switch 700 reduces the effects of any cross-talk signals generated by undesired reflections in switches 500a-c,as described above with regard to FIG. 11 and FIGS. 12A-12B.

[0107] Although the present invention has been described with several embodiments, a myriad of changes, variations, alterations, transformations, and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompasses such changes, variations, alterations, transformations, and modifications as fall within the spirit and scope of the appended claims.