SEGMENTED THIN FILM ADD/DROP SWITCH AND MULTIPLEXER

Abstract: An optical switch and WADM uses a channel selector (10) to provide channel selection and reconfigurable operation. The channel selector (10) includes a segmented filter portion (100) and a highly reflecting mirror (110). The channel selectors (10) can be cascaded to form an N-wavelength channel WDM system. The WADM allows for the selection of a wavelength channel from a multitude of channels by moving the appropriate channel selector (10) into the path of the light beam.

Description: SEGMENTED THIN FILM ADD/DROP SWITCH AND MULTIPLEXER CROSS-REFERENCE TO RELATED APPLICATIONS This Application claims the benefit of priority under 35 U.S.C. § 119(e) for U.S. Provisional Patent Application Serial No. 60/148,862 filed on August 13, 1999, the content of which is relied upon and incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to optical switches, and particularly to an optical switch using thin film filters. 2. Technical Background Wavelength Add/Drop Multiplexers (WADMs) are currently gaining considerable attention in the development of communication systems because of the flexibility, capacity, and transparency they provide. WADMs allow service providers to efficiently reconfigure networks to meet changing service requirements. This is especially helpful in metropolitan area applications because it provides the capability of adding and dropping communication payloads at each node in the communication ring. WADMs also provide the same capability for long-distance applications. At any local node, wavelength channels that are destined for the local node are directed into a drop port and integrated with local traffic. Other wavelength channels which are merely passing through the node remain undisturbed. Thus, switching is performed in the optical domain, and the inefficiencies associated with optical to electrical domain conversion are avoided. In order to exploit the full capability of optical domain switching, WADMs must be reconfigurable and wavelength channel selectable. These two attributes enable service providers to allocate bandwidth on demand and redistribute wavelengths where required in an optical network. Most current technologies allow an add/drop node to be reconfigured; however, only a few provide full reconfigurability and channel selectability without interrupting adjacent channels. There are several issues that need to be addressed before the capacity of WDM systems can be increased. Obviously, the ability to use more of the available spectrum is one way to increase capacity. One way to accomplish this is by increasing the number of wavelength channels in the system by reducing the spacing between channels. However, this problem is compounded by the need for broad band channels that carry more information. It has been proposed to increase the flexibility of the channel shape by differentially heating a fiber Bragg grating from one end to another. This allowed the grating to be chirped, expanding its reflected spectrum. By controlling the absolute temperature, the shape of the center of the channel could be manipulated. While this flexibility is impressive, it has a major drawback. It requires significant monitoring and control functionality to be added to the component to make it useful. Additionally, this device is an 'analog' type device. It will have a tendency to drift with time and temperature. This points out a need for a WDM switch that flexibly selects individual wavelength channels in a system, whereby wavelength channels are flexibly allocated within the communications system. SUMMARY OF THE INVENTION The WDM switch and WADM of the present invention provides flexible selection and allocation of wavelength channels with a WDM communications system. The switch and WADM use a channel selector for wavelength channel selection. The channel selector is composed of multiple single channel filter elements and a highly reflecting mirror that covers the wavelength range of interest. The channel selector also provides the ability to band pass filter the optical signal. The band pass filter can be selected for either wide band or narrow band operation depending on the requirements of channel spacing. One aspect of the present invention is an optical device for directing the light signal having a plurality of wavelength channels. The optical device includes a wavelength selector segment that includes a plurality of filters corresponding to the plurality of wavelength channels; and a reflector segment disposed adjacent to the plurality of filters. Another aspect of the invention is an optical device for directing a light signal having N-wavelength channels, wherein N is an integer. The optical device includes an input port for directing the light signal into the optical device. N-channel selectors are coupled to the input port, each of the channel selectors includes a wavelength selector segment having a filter corresponding to a wavelength channel of the N- wavelength channels, and a reflector segment disposed adjacent the wavelength selector segment. The optical device also includes N-drop ports, each drop port of the N-drop ports is coupled to a corresponding channel selector whereby a selected wavelength channel is directed into a drop port when the light signal is incident a wavelength selector segment corresponding to the selected wavelength. An output port is coupled to the N-channel selectors whereby the light signal is directed out of the optical device. Another aspect of the invention is a method of directing a light signal having a plurality of wavelength channels. The method includes the steps of providing an optical device having a wavelength selector segment that includes a plurality of filters corresponding to the plurality of wavelength channels, and a reflector segment disposed adjacent the plurality of filters, whereby the light signal is incident the reflector segment causing substantially all of the light signals to be reflected. A wavelength channel is selected by moving the optical device in a first direction, such that the light signal is incident a first filter of the plurality of filters, whereby a first wavelength channel propagates through the wavelength selector segment and other wavelength channels of the plurality of wavelength channels are reflected. Another aspect of the invention is a method for directing a light signal having a plurality of wavelength channels along an optical path in an optical device. The optical device includes an input port for directing a light signal into the optical device, a drop port for removing the selected wavelength channel from the light signal, and an output port for directing the light signal out of the optical device. The method includes the steps of providing a segmented channel selector having a wavelength selector segment and a reflector segment disposed adjacent to the wavelength selector segment, whereby the light signal is incident the reflector segment causing the light signal to be reflected into the output port. The channel selector is moved relative to the optical path such that the light signal is incident the wavelength selector whereby the selected wavelength channel passes through the wavelength selector segment into the drop port and other wavelength channels of the plurality of wavelength channels are reflected into the output port. Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operation of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram of the segmented channel selector according to a first embodiment; Figure 2 is a diagram of the segmented channel selector according to a first embodiment showing channel selection; Figure 3 is a linearly variable channel selector according to a second embodiment; Figure 4 is a diagram of a channel selector having a bandpass filter in accordance with a third embodiment; Figure 5 is a is a diagram of a channel selector and bandpass filter in accordance with a fifth embodiment ; Figure 6 is a method of manufacturing a thin film channel selector; Figure 7 is an alternate method of manufacturing a thin film channel selector; Figure 8 is a plan view of a switch incorporating the channel selector disclosed in the fifth embodiment of the present invention; Figure 9 is a diagram of an WADM switch using the channel selector of the fifth embodiment of the present invention; Figure 10 is a diagram view of a flexure arm and chuck in the mechanical implementation of the switch and WADM depicted in Figures 8 and 9; Figure 11 is a diagram view of a chuck assembly used to implement the switch and WADM depicted in Figures 8 and 9; Figure 12 is a detail view of a switch actuator used to actuate the flexure arm depicted in Figure 10; Figure 13 is a detail view of a thrust bearing used in the chuck assembly depicted in Figure 10; Figure 14 is a graph comparing switching losses for a damped switch and a switch that has not been damped; and Figure 15 is a diagram of an alternate chuck assembly used to implement the switch and WADM depicted in Figures 8 and 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. An exemplary embodiment of the Channel selector of the present invention is shown in Figure 1 , and is designated generally throughout by reference numeral 10. In accordance with the invention, the present invention for an optical switch or WADM 1 includes a channel selector 10. Channel selector 10 may include multiple single channel filter elements and a highly reflecting mirror that covers the wavelength range of interest. When implemented in an optical switch apparatus or a WADM, the channel selector 10 is movable in two orthogonal degrees of motion, making the switch or WADM channel selectable and reconfigurable without impacting adjacent channels. These features provide many advantages that are not found in conventional add/drop switch technologies. The present invention has low optical loss. The light signal is not filtered by tuning-through adjacent filters when changing wavelength channels. As a result, there is no cross-talk due to "tuning-through." The channel selector has low non-uniformity, is small in size, and integrated. The switches and WADMs that incorporate the channel selector are reconfigurable, and provide latching switch states. The basic design of the WADM or switch is a two-channel module. The two-channel modules can be cascaded to add/drop N- wavelengths, where N is an integer. As embodied herein and depicted in Figure 1, channel selector 10 according to a first embodiment of the present invention is disclosed. Channel selector 10 includes wavelength selector 100 and a reflector segment 110. Wavelength selector segment 100 is an array of discrete wavelength channel filters 102-108, which each passing a spectral band corresponding to a wavelength channel. As shown, filter segment 102 transmits wavelength channel λ] and reflects all other wavelength channels, in this case, wavelength channels λ 2 and λ 3 . As embodied herein and depicted in Fig. 2, wavelength channel selection in accordance with the present invention is disclosed. As shown, channel selector 10 is moved with respect to the optical beam to select a desired wavelength channel. In this example, channel selector 10 is reconfigured from passing wavelength channel λ] to passing wavelength channel λ 2 . One salient feature of the present invention is that reflector segment 110 is disposed adjacent to all channel filters 102-108. The arrangement of filter elements 102 -108 allows for channel selection capability without "tuning through" adjacent channels. Channel selector 10 is initially positioned such that wavelength channel λι is selected by illuminating element 102. By moving filter switch 10 with respect to the incident beam to the high reflector, all of the wavelength channels are reflected. The selection of another channel is effected by moving channel selector 10 such that the relative movement of the beam is along reflector segment 110 until the beam is positioned adjacent to the selected filter 108. Channel selector 10 is then moved to position the optical beam onto the selected filter 108. Since individual channel selectors access a different portion of the system spectrum, one of ordinary skill in the art will recognize that multiple channel selectors can be cascaded in a WADM or switch device. A set of four channel selectors 10, each having four different channel filters can be used to access any channel in a 16 wavelength channel system. As embodied herein and depicted in Figure 3, a linearly variable channel selector 10 is disclosed in accordance with a second embodiment of the present invention. One of ordinary skill in the art will recognize that by moving linearly variable filter 100 as shown, channel selector 10 can be tuned to any center wavelength. When incorporated into an optical switch or WADM, a tunable optical switch or WADM is created. As embodied herein, and depicted in Figure 4, a channel selector 10 having two band pass filter segments, Al and A2, is disclosed in accordance with a third embodiment of the present invention. Wavelength selector segment 100 includes filter segment 114 that is tuned to wavelength channel Al and filter segment 116 that is tuned to wavelength channel A2. Wavelength channels Al and A2 are both tuned to the same wavelength channel. However, filter segment 114 (Al) has a narrow pass band, whereas filter segment 116 (A2) has a broad pass band. In this instance, channel Al has a 50 Ghz pass-band and channel A2 has a 100 GHz pass band. During the switching motion, the switch moves from reflector segment 110 to filter segment 114 to thereby provide a 50 GHz pass band. Systems using 50 Ghz wide channels typically separate adjacent channels by 0.4 nm. If channel A were to be configured as a 100 GHz wide channel, then the switch would move through Al to A2. Systems using 100 GHz channel widths typically separate adjacent channels by 0.8 nm. One of ordinary skill in the art will recognize that moving channel selector 10 through Al has no effect on any adjacent channels. As channel selector 10 settles into A2, there is no impact on adjacent channels. As embodied herein and depicted in Figure 5, a channel selector 10 having two wavelength channel filters each including two-pass bands is disclosed in accordance with a fourth embodiment of the present invention. Wavelength selector segment 100 includes filter sub-segment 114 (Al), filter sub-segment 116 (A2), filter sub-segment 119 (Bl), and filter sub-segment 120 (B2). Filter sub-segment 114 passes wavelength channel A with a 50 GHz pass band. Filter sub-segment 116 passes wavelength channel A and has a 100 GHz pass band. Filter sub-segment 118 passes wavelength channel B and has a 50 GHz pass band. Filter sub-segment 120 passes wavelength channel B and has a 100 GHz pass band. Sub-segments 114,116, 118, and 120, are interleaved allowing channel selector 10 to shift from reflector segment 110 to sub- segments 114, 116, 118, or 120 directly. By interleaving the sub-segments, the light beam is directed onto the desired segment only, without the intermediate step associated with the channel selector 10 depicted in Figure 4. One of ordinary skill in the art will recognize that channel selector 10 can be implemented having a circular shape. Channel selector 10 can also be implemented to move in a circular motion as needed. As embodied herein and depicted in Figure 6, a method of manufacturing channel selector 10 is disclosed. First, substrate 130 is formed. Substrate 130 is masked using a photolithographic technique. Alternatively, it is cut into strips and masked mechanically before being coated with the reflector segment material. Reflector segment 110 may be of any suitable type, but there is shown by way of example a reflective metallic material. One of ordinary skill in the art will recognize that a dielectric material may also be used to fabricate reflector segment 110. Second, the broader spectral filter segment 116 is deposited on reflector segment 110. Subsequently, segment 116 is masked. The narrower filter segment 114 is then deposited over the unmasked portion of segment 116. Finally, broad band filter segment 116 and narrow band filter segment 114 are masked and a high reflective coating such as a gold film is applied to reflector segment 110. The thickness of the gold film must be chosen appropriately to achieve high reflectance and minimize interference effects. It is noted that the switch will suffer small transient losses during switching from the effects of scattering at the gold film edge. However, the area of the edge is small compared to the area of the beam, and hence, the scattering losses are inconsequential. One of ordinary skill in the art will appreciate that each filter segment is matched in phase to adjacent filter segments. As embodied herein and depicted in Figure 7, an alternate method of manufacturing channel selector 10 is disclosed. Layers of thin-films representing segments 110, 114, and 116 are directly deposited onto substrate 130. A photolithographic masking process is used to ensure that segments 110, 114, and 116 are perfectly matched at the interfaces. As embodied herein and depicted in Figure 8, a two-channel drop switch 1 is disclosed. Switch 1 includes input port 20 which directs a light signal toward drop port 26. Channel selector 100 is disposed between input port 20 and drop port 26 and reflects the light signal toward drop port 22. Channel selector 200 is disposed between channel selector 100 and drop port 22 and ultimately, reflects the light signal toward output port 24. Input port 20, drop ports 22 and 26, and output port 24 may be of any suitable type, but there is shown by way of example an optical fiber connected to a GRIN lens or any other suitable collimator. Channel selectors 100 and 200 may be of any suitable type, but there is shown by way of example in the detail view of Figure 8, channel selectors consisting of a single segment wavelength selector 102 (202) and a reflector segment 110 (210) in accordance with a fifth embodiment. Wavelength selector 102 passes wavelength channel λ \ and reflects all other wavelength channels. Wavelength selector 202 passes wavelength channel λ 2 and reflects all other wavelength channels. Switch 1 operates as follows. Switch 1 independently moves channel selectors 100 and 200 in the direction A- A perpendicular to the optical beam to achieve switching. The relative motion of the beam with respect to the filter is shown in the detail view of Figure 8. For example, when channel selector 100 is positioned to have the beam incident filter segment 102, wavelength channel λi is resonant with the thin film filter segment 102, and wavelength channel λi passes through channel selector 100 into drop port 26. The remaining channels are uniformly reflected from filter segment and directed toward channel selector 200. In similar fashion, if the incident beam is positioned on filter segment 202, wavelength channel λ 2 passes through channel selector 200 into drop port 22. The remaining channels are directed by channel selectors 100 and 200 into output port 24. Switch 1 is reconfigured by moving either, or both channel selectors 100 and 200 to position the beam on reflecting segments 110 or 210, as desired. When the light signal is incident reflecting segments 110 or 210, all channels are uniformly reflected into output port 24. Thus, either λi or λ 2 , or both, can be dropped or included in the output signal directed into output port 24. One of ordinary skill in the art will recognize that switch 1 shown in Figure 8 can be converted into an add/drop switch by providing an add port for each drop port provided. Furthermore, switch 1 in Figure 8 can be cascaded to accommodate more wavelength channels. As embodied herein and depicted in Figure 9, a WADM 1 using the channel selectors shown in Figure 8 is disclosed. Input port 20 directs the light signal into WADM 1, toward channel selector 100, which selectively filters wavelength channel λj. As discussed above, when reflector segment 110 (Figure 8) is in the path of the light beam, all wavelength channels are reflected toward channel selector 200 (λ 2 ). If the light signal is incident filter segment 102, wavelength channel λ \ is directed into drop port 26. At the same time, add port 34 directs add channel λ] into WADM 1 through the opposite side of filter segment 102 and add channel λi is inserted into the outgoing optical beam toward channel selector 200 (λ 2 ). As depicted, channel selector 200 is optically coupled to channel selector 300(λ 3 ). Depending on the position of channel selector 300, wavelength channel λ can be dropped into drop port 28 and a corresponding add channel can be added via add port 38. Channel selector 300 is optically coupled to channel selector 400 (λ N ). Again, depending on the position of channel selector 400, wavelength channel λπ can be dropped into drop port 30 and a corresponding add channel can be added via add port 36. Finally, the output light signal reflects off channel selector 400 into output port 24. Channel selectors 100-400 are actuated independently. Thus, an N-stage cascaded device can independently drop or add N-wavelength channels. One of ordinary skill in the art will recognize that other channel selector configurations (see Figures 2-5) can be used depending on system needs. As embodied herein and depicted in Figure 10, a perspective view of switch 1, showing mechanical actuation details is disclosed. Flexure arms 50 and 60 are used to actuate channel selectors 100-400 in the switch and WADM depicted in Figures 8 and 9, respectively. Channel selector 100 is mounted in chuck 52 on flexure arm 50. Channel selector 200 is mounted in chuck 62 on flexure arm 60. Flexure structures 54 and 64 provide fine angular adjustments as well as coarse angular adjustments with two degrees of freedom. Flexure structure 54 in flexure arm 50 provides an angle adjustment in the horizontal plane and flexure structure 64 in flexure arm 60 provides angular adjustments in the vertical plane. Angular adjustments are achieved by inserting a proper tool into slot to bend the flexures in either direction. The size of the deforming flexure member in each flexure 54 and 64 is chosen to provide adequate mechanical strength in combination with adequate deformability by the special tooling. These angular adjustments provided by flexures 54 and 64 allow channel selectors 100 and 200 to be aligned to each other within 20 arc seconds (100 micro-radians). Flexure arms 50 and 60 also include indented regions 588 and 688, respectively. These regions are provided to accomodate thrust bearings 58 and 68, respectively. Flexure arms 50 and 60 also include holes 586 and 686, respectively. Holes 586 and 588 are used to accommodate a connector or screw (not shown) which acts as a pivot or axle. The screw is co-linear with the axis of rotation. This arrangement will be discussed in more detail below. As embodied herein and depicted in Figure 11, a perspective view of chuck assembly 70 is disclosed in accordance with the present invention. The switch 1 disclosed in Figure 8 is housed by base plate 72. The various compartments formed in base plate 72 were formed by a machining process to accommodate collimators 20, 22, 24, and 26, solenoids 56 and 66, and flexure arm assemblies 50 and 60 depicted in Figure 10. One of ordinary skill in the art will recognize that it is a relatively simple task to produce more compartments in a larger block of aluminum when implementing the WADM depicted in Figure 9. In one embodiment of the chuck assembly depicted in Figure 11 , flexure arms 50 and 60 are movable with one degree of freedom. Thrust bearing assemblies 58 and 68 are formed around flexure arms 50 and 60 and are attached to base plate support 74. Thrust bearings 58 and 68 are fastened with a spring-loaded connector on base plate support 74 to form a pivot co-linear with the axis of rotation. Thrust bearings 58 and 68 limit the movement of flexure arms 50 and 60 in directions orthogonal to the direction of rotational motion. Channel Selectors 100 and 200 are mounted to chucks 52 and 62, which are indented regions formed at the ends of flexure arms 50 and 60, respectively. Flexure arms 50 and 60 are rotatable around the axis of rotation and move channel selectors 100 and 200 between two or more positions in switch 1, depending on the type of channel selectors used (See Figures 2-5). Actuators 56 and 66 are coupled to flexure arms 50 and 60, respectively. Actuators 56 and 66 actuate the flexure arms causing them to rotate about the rotational axis within a range of 4 degrees to obtain the channel selector functions discussed above for adding or dropping a wavelength channel. In another embodiment, two-degrees of freedom can be incorporated into switch 1 by mounting two mini slides (not shown) under thrust bearing assemblies 58 and 68. In this embodiment, base plate 70 is machined to accommodate two additional solenoids for actuating the two mini-slides. Actuators 56 and 66 may be of any suitable type, but there is shown by way of example magnetic latching bi-state solenoids. One of ordinary skill in the art will recognize that a commercially available latching relay is also be suitable. As embodied herein and depicted in Figure 12, a detail view of the actuation mechanism of flexure arms 50 and 60 is disclosed. The description relates to flexure arm 50, but one of ordinary skill in the art will recognize that the description is equally applicable to flexure arm 60 as well. Flexure arm 50 includes holes 566 and 568 which accommodate damping springs 562 and 564. Plunger 560 of solenoid 56 pushes damping leaf spring 560 toward flexure arm 50. Arm 562 of damping leaf spring 560 is disposed in hole 566 and acts to push flexure arm 50 downward. This downward movement causes flexure arm 50 to rotate around the axis of rotation, to thereby move channel selector 200 (Figure 11) into position. Damping spring 564 is connected to base plate support 74 and is inserted into hole 568. Spring 564 resists the downward movement of flexure arm 50 and supplies a damping resistance that mitigates unwanted vibrations that would otherwise result in jitter. As embodied herein and depicted in Figure 13, a detail view of thrust bearing assembly 58 is disclosed. One of ordinary skill in the art will recognize that the description is equally applicable to thrust bearing assembly 68. As discussed above, flexure arm 50 includes indented regions 588 which are disposed about hole 586. Thrust bearings 584 fit within indented regions 588. Screw 580 is disposed in holes 586 and 686. As discussed above, flexure arm 50 and thrust bearings 584 rotate around screw 580 allowing 4° of movement between switch positions. Screw 580 presses against wave washer 582 and thrust bearings 584 to form spring loaded thrust bearing assembly 58. Screw 580 applies approximately 4 lb. of force to thrust bearings 584. This force substantially eliminates channel selector jittering during rotational movement. Thrust bearing assembly 58 exceeds the vibration/shock requirement set by Bellcore standards. The thrust bearings 584 used in assembly 58 are designed for rotation of 500 rpm (revolution per min) with a long lifetime. Thus, the design is durable and reliable. Any wearing that does occur will be compensated for by the spring-loading mechanism 582. Figure 14 is a plot showing the improvement in transient excess loss due to the use of thrust bearing assemblies 58 and 68 discussed above. The plot represents the excess loss that is generated in neighboring wavelength channels when flexure arm 50 is actuated to move channel selector 100 to drop wavelength channel λl. Curve 300 shows actuation of wavelength channel λl . As shown by curve 304, wavelength channel λ3 experiences significant vibrations without the damping provided by thrust bearing assembly 58. This results in transient excess-loss greater than 15dB for a maximum duration of 100msec. As shown by curve 306, wavelength channel λ3 experiences less than 0.5 dB excess loss with the damping provided by thrust bearing assembly 58. Note that with the damping, the excess loss occurs within the 10msec switch actuation time. As embodied herein and depicted in Figure 15, a diagram of an alternate chuck assembly 80 is disclosed. Channel selector 100 is disposed and glued into chuck 52. Chuck 52 is an indented region formed at one end of flexure arm 50. Channel selector 200 is disposed and glued into chuck 62. Chuck 62 is an indented region formed at one end of flexure arm 60. Flexure arms 50 and 60 are connected to Schneeberger micro- frictionless slides 70 and 90, respectively. Slides 70 and 90 provide a very smooth motion with a deviation from the plane of motion of under 2 microns. Slide 70 is indirectly connected to solenoid 56 via spring 74 and arm 50. Slide 90 is indirectly connected to solenoid 66 via spring 94 and arm 60. Flexure arm 50 is connected to a second spring 72, whereas flexure arm 60 is connected to spring 92. Springs 72 and 92 act as a loading force on linear slides 70 by being bolted onto flexure arms 50 and 60, respectively. This arrangement ensures a smoother motion. Flexure arm 50 is mounted onto flexure member 54, which has a motion horizontal to the beam path. Flexure arm 60 is mounted on flexure member 64, which has a motion perpendicular to the beam path. This arrangement is very similar to the first mechanical implementation discussed above. Flexure members 54 and 64 provide a means for ensuring beam parallellism, and tuning the incident angle of the light beam onto channel selectors 100 and 200. ±nus, me piυi uepicieu m πgure 14 is applicable to the cnucK assemoiy oi figure , as well. Solenoids 56 and 66 are magnetic latching, bi-state solenoids. For example, magnets 560 are provided at either end of solenoid 56. Solenoid 66 is also equipped with magnets 660. Solenoids 56 and 66 are encapsulated in a vibration absorbing foam which further serves to mitigate the effects of vibration on transient excess loss. Springs 74 and 94 serve to absorb vibrations inherent in the switching motion of solenoids 56 and 66. Springs 72 and 92 oppose the motion of solenoids 56 and 66, respectively. Vibrations are reduced by slowing down the motion of the solenoid at the end of the stroke. Thus, vibrations are further damped, and a smooth return force is ensured when the solenoids retract. It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims: What is claimed is: 1. An optical device for directing the light signal having a plurality of wavelength channels, said optical device comprising: a wavelength selector segment that includes a plurality of filters corresponding to the plurality of wavelength channels; and a reflector segment disposed adjacent to said plurality of filters. 2. The optical device of claim 1, wherein the plurality of filters are arranged as an array of discrete filter elements. 3. The optical device of claim 2, wherein a wavelength channel is selected by moving the wavelength selector segment such that the light signal is incident a corresponding discrete filter segment. 4. The optical device of claim 3, wherein the corresponding discrete filter element transmits a selected wavelength channel and reflects all other wavelength channels. 5. The optical device of claim 2, wherein each discrete filter element includes a first sub-segment and a second sub-segment. 6. The optical device of claim 5, wherein the first sub-segment is a first band-pass filter defining a first wavelength pass band. 7. The optical device of claim 5, wherein the second sub-segment is a second band-pass filter defining a second wavelength pass band. 8. The optical device of claim 1, further comprising: an input port for directing the light signal into the optical device; a drop port wherein a wavelength channel is directed out of the optical device when the light signal is incident the wavelength selector element; and an output port wherein all of the plurality of wavelength channels are directed out of the optical device when the light signal is incident the reflector segment. 9. The optical device of claim 8, wherein the wavelength channel is directed into the drop port when the light signal is incident a selected filter of the plurality of filters that corresponds to the wavelength channel. 10. The optical device of claim 12, wherein the wavelength channels that do not correspond to the selected filter are reflected by the selected filter into the output port. 11. The optical device of claim 9, further comprising an add port, wherein an add channel, occupying a spectral region substantially the same as the wavelength channel directed into the drop port, is directed into the optical device. 12. The optical device of claim 1 1, wherein the add channel passes through the selected filter into the optical device. 13. The optical device of claim 8, further comprising an add port, wherein an added wavelength channel is directed into the optical device when incident the wavelength selector element. 14. The optical device of claim 1, further comprising a channel selector that includes the wavelength selector segment and the reflector segment disposed on a common substrate. 15. The optical device of claim 14, further comprising a chuck assembly adapted to move the channel selector relative to the light signal. 16. The optical device of claim 15, wherein the chuck assembly further comprises: a flexure arm having the chuck disposed on a first end for holding the channel selector in a fixed position relative to said flexure arm, and a pivot disposed on a second end at an axis of rotation; and a plate support connected to said flexure arm at said pivot, wherein said flexure arm is rotatable around said pivot to thereby provide the channel selector with one degree of motional freedom. 17. The optical device of claim 16, wherein the pivot further comprises a thrust-bearing assembly disposed between the flexure arm and the plate support. 18. The optical device of claim 17, wherein the thrust-bearing assembly further comprises: a first thrust bearing disposed adjacent to plate support, and adjacent a first side of the second end; a second thrust bearing disposed on a second side of the second end; and a spring-loaded fastener extending through said second thrust bearing, the second end, said first thrust bearing, and the plate support wherein said spring-loaded fastener is co-linear with the axis of rotation. 19. The optical device of claim 16, wherein the flexure arm further comprises a flexure structure that provides an angular adjustment to the flexure arm to move the channel selector relative to the light signal. 20. The optical device of claim 19, wherein the angular adjustment to the flexure arm is adjustable in at least two dimensions. 21. The optical device of claim 16, further comprising a slide device connected to an underside of the plate support, whereby the flexure arm and plate support are slidable along a linear direction providing the channel selector with at least two degrees of motional freedom. 22. The optical device of claim 15, wherein the chuck assembly further comprises: a chuck having a first end adapted to hold the channel selector, and a second end; a micro-frictionless slide connected to said chuck, whereby said chuck is movable along a first linear direction; a first spring connected to said second end; and an actuator connected to said spring wherein said actuator moves said micro- frictionless slide in the first linear direction. 23. The optical device of claim 22, wherein the actuator is a magnetic latching bi -state solenoid. 24. The optical device of claim 22, further comprising a second spring attached proximate the first end for opposing actuator movement. 25. The optical device of claim 22, further comprising a flexure coupled to the chuck whereby an angular position of the chuck is adjusted. 26. An optical device for directing a light signal having N-wavelength channels, wherein N is an integer, said optical device comprising: an input port for directing the light signal into the optical device; N-channel selectors coupled to said input port, each of said channel selectors includes a wavelength selector segment having a filter corresponding to a wavelength channel of the N-wavelength channels, and a reflector segment disposed adjacent said wavelength selector segment; N-drop ports, each drop port of said N-drop ports is coupled to a corresponding channel selector whereby a selected wavelength channel is directed into a drop port when the light signal is incident a wavelength selector segment corresponding to said selected wavelength; and an output port coupled to said N-channel selectors whereby the light signal is directed out of the optical device. 27. The optical device of claim 26, wherein wavelength channels that do not correspond to the selected wavelength channel are directed into the output port. 28. The optical device of claim 26, further comprising N-add ports, each add port of said N-add ports is coupled to the corresponding channel selector and drop port, whereby a selected add channel is directed into the optical device when the selected wavelength channel is directed into the drop port. 29. The optical device of claim 28, wherein the selected wavelength channel and the selected add-wavelength channel occupy a spectral region that has substantially the same set of wavelengths. 30. A method of directing a light signal, having a plurality of wavelength channels said method comprising the steps of: providing an optical device having a wavelength selector segment that includes a plurality of filters corresponding to the plurality of wavelength channels, and a reflector segment disposed adjacent said plurality of filters, whereby the light signal is incident said reflector segment causing substantially all of said light signals to be reflected; and selecting a wavelength channel by moving said optical device in a first direction, such that the light signal is incident a first filter of said plurality of filters, whereby a first wavelength channel propagates through said wavelength selector segment and other wavelength channels of said plurality of wavelength channels are reflected. 31. The method of claim 30, wherein the step of selecting further comprises: moving the optical device in a direction opposite the first direction causing a relative motion of the light signal from the first filter to the reflector segment; moving the optical device to thereby cause a relative motion of the light signal along the reflector segment to a point adjacent a second filter; and selecting a second wavelength channel by moving the optical device to thereby cause a relative motion of the light signal from said point adjacent to said second filter, whereby a second wavelength channel propagates through said wavelength selector segment and other wavelength channels of said plurality of wavelength channels are reflected. 32. A method for directing a light signal having a plurality of wavelength channels along an optical path in an optical device, said optical device includes an input port for directing a light signal into said optical device, a drop port for removing the selected wavelength channel from said light signal, and an output port for directing said light signal out of said optical device, said method comprising the steps of: providing a segmented channel selector having a wavelength selector segment and a reflector segment disposed adjacent to said wavelength selector segment, whereby the light signal is incident said reflector segment causing the light signal to be reflected into the output port; and moving said channel selector relative to the optical path such that the light signal is incident said wavelength selector whereby the selected wavelength channel passes through said wavelength selector segment into the drop port and other wavelength channels of the plurality of wavelength channels are reflected into the output port. 33. A chuck assembly adapted to move a device, said chuck assembly comprising: a flexure arm having a first end, a flexure member, and a second end; a chuck disposed on said first end and adapted to hold the device in a fixed position relative to said first end, whereby said flexure member is adapted to align said chuck to a predetermined position; and a pivot member connected to said second end at an axis of rotation, whereby said flexure arm is rotatable around said axis of rotation. 34. The apparatus of claim 33, further comprising a thrust-bearing assembly disposed between the flexure arm and a support member. 35. The apparatus of claim 34, wherein the thrust-bearing assembly further comprises: a first thrust-bearing disposed adjacent the support, and adjacent a first side of the second end; a second thrust-bearing disposed on a second side of the second end; and a spring-loaded fastener extending through said second thrust-bearing, the second end, said first thrust-bearing, and the support, whereby said spring-loaded fastener is co-linear with the axis of rotation. 36. A chuck assembly adapted to move a device, said chuck assembly comprising: a chuck having a first end and a second end, wherein said first end is adapted to hold the device; a micro-frictionless slide connected to said chuck, whereby said chuck is movable along a first linear direction; a first spring connected to said second end; and an actuator connected to said spring, wherein said actuator moves said micro- frictionless slide in the first linear direction. 37. The apparatus of claim 36, wherein the actuator comprises a magnetic latching bi- state solenoid. 38. The apparatus of claim 36, wherein the actuator comprises a latching relay. 39. The apparatus of claim 36, further comprising a second spring attached proximate the first end for opposing actuator movement. 40. The apparatus of claim 36, further comprising a flexure coupled to the chuck, whereby an angular position of the chuck is adjusted.

Inventors: BOISSET GUILLAUME C, HARRIS JAMES M, KROL MARK F, WU QI, WU XINGKUN, BOISSET, GUILLAUME, C., HARRIS, JAMES, M., KROL, MARK, F., WU, QI, WU, XINGKUN
Applicants: CORNING INC, CORNING INCORPORATED
Application year: 2000
Main classification: G02B6
IPC codes: G02B6, G02B26, H04J14, H04Q11