Abstract:
An apparatus comprising a first plate having a plurality of v-shaped grooves to hold a set of optical fibers and a second plate having a v-shaped groove to hold a secondary optical fiber is disclosed. In one embodiment, the second plate being movable relative to the first plate, so that the secondary optical fiber can be selectively coupled to one of the optical fibers of the first set of optical fibers.

Description:
FIELD OF THE INVENTION 
     The invention is related to the field of optical switches; more particularly, the present invention relates to a V groove optical switch that may be used in, for example, optical networks. 
     BACKGROUND OF THE INVENTION 
     Conventional optical networks route optical signals through optical fibers and switches so that people or computers can communicate with each other through the network. However, if an optical fiber breaks, or if a switch malfunctions, the link between a node connected to the broken fiber or malfunctioning switch and the rest of the network will be severed. Thus, a broken fiber can render the network inaccessible for the person or computer connected to the broken fiber. 
     SUMMARY OF THE INVENTION 
     An apparatus comprising a first plate having a plurality of v-shaped grooves to hold a set of optical fibers and a second plate having a v-shaped groove to hold a secondary optical fiber is disclosed. In one embodiment, the second plate being movable relative to the first plate, so that the secondary optical fiber can be selectively coupled to one of the optical fibers of the first set of optical fibers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which: 
     FIG. 1 shows an example of an optical network that uses the optical interface port. 
     FIGS. 2 a ,  2   b ,  2   c ,  2   d  and  2   e  show an example of components of a silicon V groove optical switch. 
     FIGS. 3 a  and  3   b  show a mechanism for moving fibers. 
     FIG. 4 shows an alternative embodiment of the silicon V groove optical switch. 
     FIG. 5 illustrates one embodiment of a cradle and yoke mechanism in conjunction with an optical switch. 
    
    
     DETAILED DESCRIPTION 
     A V groove (v-shaped) optical switch is disclosed. In one embodiment, the V groove optical switch connects a line card to a secondary optical fiber if there is a signal loss over the primary optical fiber, thus providing a redundant feed between the line card and a working node. The V groove switch may be periodically tested to verify the satisfactory operation of the switch. 
     In one embodiment, the V-shaped groove optical switch comprises a pair of silicon plates. The plates can be constructed of many materials other than the silicon that are traditionally used in the manufacture of the optic arrays. The materials include quartz, sapphire, borosilicate glass, zirconia, metals, metallic alloys, metallic compounds and plastics. In another embodiment, the switch contains a combination of silicon and borosilicate glass plates. 
     Machine tools directly machine or model the V groove or other shaped plates. Note that shapes other than, or similar to, V grooves may be used in alternate embodiments. 
     FIG. 1 shows an example of an optical network that uses the optical interface port. As shown in FIG. 1, each channel of a given line card is connected to a given optical network unit  210 - i  through an optical fiber  211 - j ,  212 - j ,  213 - j  and  214 - j  connected to the corresponding working line interface unit. A redundant optical fiber  221 - j ,  222 - j ,  223 - j  and  224 - j  for each channel is connected to optical switch unit  160 , which in one embodiment contains form switches. The redundant optical fiber connections for each channel  1  are connected to one of the V groove switches in switch unit  160 . Similarly, the redundant optical fiber connections for channels  2 ,  3  and  4  are connected to individual separate switches in switch unit  160 . 
     If a connection between a line card and an optical network fails, the redundant connection can be used to maintain the feed between the line card and the corresponding optical network unit. For example, suppose the optical fiber  211 - 1 , which connects to channel  1  of an optical line card, via line interface unit  111 , to optical network unit  210 - 1 , fails to send optical signals between the line card and unit  210 - 1 . The loss of the signal causes gateway control module (GEM)  250  to instruct an optical switch protection controller in switch unit  160  to connect the V groove switch in switch unit  160  associated with channel  1  to channel  1  of that line card. This V groove switch can then link channel  1  of the line card to optical fiber  221 - 1 , thereby providing a redundant connection between unit  210 - 1  and the line card. The same is true for other optical network units  210 - 2 - 210 - 16  and line interfere units  121 ,  131 ,  141  and  151 . Note that a system may continue a greater or lesser number of optical network units, line interfere units and associated line cards. 
     The switch unit  160  may include feedback capability that enables the optical switch protection controller to determine the current position of a given switch. This enables the controller to determine the direction and the number of steps needed to move a given switch to make a desired connection. 
     Also, by implementing a link feedback/continuity method, the controller can be informed of the current state of a given switch by gateway control module  250 . In one embodiment, a suite of periodic tests may be added to the system to verify the satisfactory operation of a switch during system operation. For example, when a switch provides a redundant feed to a working node, the performance of the redundant feed to a working node, such as an optical network unit, can be monitored. A successful feed between the node and the switch can be detected by monitoring the remote node&#39;s receiver LOS, to verify basic continuity, using an in-band signaling over a SONET line or section communications channel. A quantitative assessment of the link performance can be determined by monitoring SONET overhead bytes B 1  and B 2  for a finer level of granularity. The frequency of implementing the feedback method may be on the order of a normal maintenance service interval. A switch failure can thus be timely detected, before a link failure, to guarantee system robustness. 
     FIGS. 2 a ,  2   b ,  2   c ,  2   d  and  2   e  show an example of components of one embodiment of a silicon v groove optical switch. FIG. 2 a  shows subassembly  205  which includes two silicon v groove plates  210  and  211 . Each silicon v groove plate has optical fiber eight v grooves  215  and eight bearing v grooves  220 . However, other embodiments may have other numbers of fiber v grooves and bearing v grooves. The plates also have two alignment grooves  225 ; again, any number of alignment grooves may be included. The optical fiber v grooves of plate  210  are aligned with the corresponding optical fiber v grooves of plate  211 , and are used in one embodiment to hold optical fibers  201  from a line card. In one embodiment, some of the optical fibers are for transmitting data, while others are for receiving data. FIG. 2 b  shows a perspective view of plates  210  and  211 . 
     FIG. 2 c  shows subassembly  235  which includes plates  230  and  231  that have optical fiber v grooves  215  and bearing v grooves  220 . In one embodiment, the fiber v grooves  215  are used to hold optical fibers  202  that connect a channel of a line card to a redundant optical fiber. Bearing v grooves  220  are used to hold bearing rods  203 . FIG. 2 d  shows another view of plates  230  and  231 . Plate  231  extends beyond plate  230  by a given distance  240 . 
     FIG. 2 e  shows the silicon v groove subassembly  205  of FIGS. 2 a  and  2   b  coupled to an additional silicon v groove plate  250  and a base plate  260 . The plates  250  and  260  have alignment grooves  225 . Plate  250  and  260  are aligned when the corresponding alignment v grooves  225  to form a diamond-shaped aperture, as shown in FIG. 2 e . Similarly, subassembly  205  is aligned with base plate  260  using alignment grooves  225  of plates  210  and  260 . 
     Subassembly  235  shown in FIG. 2 d  is placed on top of subassembly  205  shown in FIG. 2 e , so that surface  270  of plate  230  abuts surface  280  of plate  211 , and surface  270  of plate  230  abuts surface  290  of plate  250 . Bearing rods  203  are used to place fibers  202  in the correct position so that fibers  202  connect with appropriate fibers  201 . In one embodiment, by moving fibers  202  relative to fibers  201 , the silicon v groove switch can connect an appropriate channel of a line card to an appropriate redundant optical fiber. 
     FIG. 3 a  shows a mechanism  300  for moving fibers  302 . Block  310  is connected to subassembly  335 , which contains fibers  301 . Shaped memory metal lines  320  and  321  are attached to block  310 . Lines  320  and  321  may be secured to mechanism  300  by holders  326  and  327 . The lines may also be guided by guides  328  and  329 . An electrical charge can be applied to the shaped memory metal lines  320  and  321  to expand or contract the shaped memory metal. Thus, in order to move block  310  in direction  315 , an electric charge that shortens shaped memory metal is applied to line  320 , and an electric charge that expands shaped memory metal is applied to line  321 . 
     As shown in FIG. 3 b , block  310  may contain alignment v grooves  330 , so that the block  310  remains in a location that aligns fibers  302  with appropriate fibers  301 . Device  350  contains bearings  355  that fit into grooves  330 . A spring mechanism  360  is attached to each of bearings  355  so that when the lines  320  and  321  move block  310 , bearings  355  rise out of the grooves to enable block  310  to move. The spring mechanism  360  places sufficient force on the bearings so that when the lines  320  and  321  are not moving the block  310 , block  310  remains in a stationary position. 
     FIG. 4 shows an alternative embodiment of the silicon v groove optical switch. Fiber array  430 , which in one embodiment has eight fibers  470 , for example, can be used to protect fiber array  420 , which in one embodiment, has thirty-two fibers  480 , for example. Fiber arrays  420  and  430  are supported by base  410 . Base  410  may include a support groove to hold support rod  440 , which supports the fiber arrays  420  and  430 . The Base  410  may also include a groove to hold positioning rod  450 . The fiber arrays  420  and  430  may include positioning grooves  460 , which may be used to move fiber array  430  relative to fiber array  420  and base  410 , using positioning rod  450  so that the proper positioning groove of fiber array  430  is located above positioning rod  450 . 
     Due to the size, geometry, and materials of the rods and grooves, the application of the forces producing the required precise movements, of distances measured in microns, at speeds measured in milliseconds, may be crucial to reliable operation. 
     FIG. 5 illustrates one embodiment of a cradle and yoke mechanism in conjunction with an optical switch. Relevant components from FIG. 4 are included in FIG.  5 . Platform  1  is located below base  410 , which is mounted to it. Platform  1  contains a hole or opening to which the bottom of the yoke can be referenced. Yoke  2  supplies a reference to the platform  1 , and therefore the base  410 , and for the cradle  3  and spring  4 , to provide a mounting for fiber array  430 . Fiber array  430  is mounted to Cradle  3 . Spring  4  provides the force necessary to ensure the proper engagement of the fiber array  430  with the support rod  440  and the positioning rod  450  in the positioning grooves  460 . Movement is accomplished when a lateral force is applied the platform  1  and the yoke  2 . The lateral force applied between platform  1  and yoke  2  is transmitted by the line contact of yoke  2  and cradle  3 , at points  5   a  and  5   b , depending on the lateral direction of the applied force. Points  5   a  and  5   b  lie below the plane formed by the lines of contact on support rod  440  and positioning rod  450  on fiber array  430 . 
     These and other embodiments of the present invention may be realized in accordance with these teachings and it should be evident that various modifications and changes may be made in these teachings without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense and the invention measured only in terms of the claims.