Optical switching system

Abstract

An optical switching device switches optical signals completely within optical media, from an arbitrary number of N input optical fibers to a set of M output optical fibers. The invention uses a thermally-activated bimorph optical switch to redirect optical radiation emitted by a laser light source, or from the end of an optical fiber, to an input end of another optical fiber. The modulated optical radiation from the input fiber optic bundle is collimated into parallel beams and projected in free space across the tops of an array of microcantilever bimorph optical switches. When selected, a particular switch is activated, thereby causing a first bimorph switch element to pop up, and intercept and reflect the optical radiation at an angle approximately 90° to the original optical path direction. This reflected radiation is intercepted by another essentially identical bimorph switch element, located above or below the first switch element, that directs the radiation in a plane essentially parallel to that of the original beam plane, but above or below the original plane, and at approximately right angles to the original beam direction. The optical radiation is directed by the second switch element to output optical fiber collimating optics. This radiation is then coupled into the selected output optical fiber.

What is claimed is:  
     
         1 . An optical switch for directing at least one optical beam from a first propagation plane to a second propagation plane that is parallel with the first propagation plane, comprising: 
 a first switch portion having a substantially-planar first reflective surface portion, the first reflective surface portion operable to move in a first pitch plane between at least a first deflection angle and a second deflection angle, when at the first deflection angle, the first reflective surface portion for intercepting the optical beam propagating along a first propagation path in the first propagation plane and for reflecting the optical beam at a first reflection angle into an intermediate propagation path, and when at the second deflection angle, the first reflective surface portion for not intercepting the optical beam; and    a second switch portion having a substantially-planar second reflective surface portion, the second reflective surface portion operable to move in a second pitch plane between at least the first deflection angle and the second deflection angle, the second pitch plane being substantially perpendicular to the first pitch plane, when at the first deflection angle, the second reflective surface portion for intercepting the optical beam propagating along the intermediate propagation path and for reflecting the optical beam at a second reflection angle into a second propagation path in the second propagation plane, and when at the second deflection angle, the second reflective surface portion for not intercepting the optical beam.    
     
     
         2 . The optical switch of  claim 1  wherein the first reflective surface portion reflects the optical beam into the intermediate propagation path such that the intermediate propagation path is substantially perpendicular to the first and second propagation planes.  
     
     
         3 . The optical switch of  claim 1  wherein the second reflective surface portion reflects the optical beam into the second propagation path such that the second propagation path is substantially perpendicular to the first propagation path.  
     
     
         4 . The optical switch of  claim 1  wherein the first and second deflection angles are approximately 45 degrees, and the first and second reflection angles are approximately 90 degrees.  
     
     
         5 . The optical switch of  claim 1  wherein the first and second reflective surface portions are substantially parallel and are disposed on either side of the second propagation plane when at the second deflection angle.  
     
     
         6 . The optical switch of  claim 1  wherein the first reflective surface portion intersects the first propagation plane at approximately 45 degrees when at the first deflection angle, and the second reflective surface portion intersects the second propagation plane at approximately 45 degrees when at the first deflection angle.  
     
     
         7 . The optical switch of  claim 1  wherein: 
 the first switch portion further comprises a first paddle disposed adjacent the first propagation path, and having a fixed portion and a free end, with the first reflective surface portion adjacent the free end, the first paddle operable to bend upon a change in temperature, thereby moving the first reflective surface portion between the first and second deflection angles; and  
 the second switch portion further comprises a second paddle oriented substantially perpendicular to the first paddle, the second paddle disposed adjacent the second propagation path, and having a fixed portion and a free end, with the second reflective surface portion adjacent the free end, the second paddle operable to bend upon a change in temperature, thereby moving the second reflective surface portion between the first and second deflection angles.  
 
     
     
         8 . The optical switch of  claim 7  wherein the first and second paddles each include: 
 an upper layer having a first coefficient of thermal expansion; and  
 a lower layer mechanically coupled to the upper layer, and having a second coefficient of thermal expansion that is different from the first coefficient of thermal expansion,  
 where the change in temperature causes the upper and lower layers to change in size at different rates due to the differences in coefficients of thermal expansion, thereby creating stress in the paddle and causing the paddle to bend.  
 
     
     
         9 . The optical switch of  claim 8  wherein the upper layer includes a resistive heater portion that generates heat upon passage of an electric current there through.  
     
     
         10 . The optical switch of  claim 8  further comprising an electrically-insulating layer disposed between the upper and lower layers.  
     
     
         11 . The optical switch of  claim 10  wherein the electrically-insulative layer is a material selected from the group consisting of SiO 2 , SiC, Si 3 N 4 , Si x O y N z , and H x Si y C z .  
     
     
         12 . The optical switch of  claim 10  further comprising a bonding layer disposed between the electrically-insulative layer and the lower layer.  
     
     
         13 . The optical switch of  claim 12  wherein the bonding layer is a material selected from the group consisting of Cr, Ti, TiW, TiN, nichrome, and alloys thereof.  
     
     
         14 . The optical switch of  claim 8  wherein the lower layer has a coefficient of thermal expansion greater than that of the upper layer.  
     
     
         15 . The optical switch of  claim 8  wherein the lower layer is an optically-reflective metal selected from the group consisting of Au, Al, Pb, and Zn.  
     
     
         16 . The optical switch of  claim 8  wherein the upper layer is doped polysilicon having a coefficient of thermal expansion less than that of the lower layer.  
     
     
         17 . The optical switch of  claim 8  wherein the upper layer is disposed only between the fixed portion and a point located between the fixed portion and the free end, whereby a portion of the lower layer extends beyond the upper layer at the free end of the first and second paddles.  
     
     
         18 . The optical switch of  claim 17  wherein the portion of the lower layer extending beyond the upper layer of the first and second paddle comprises the first and second reflective surface portions, respectively, which remain substantially flat when at the first deflection angle, such that the first and second reflective surface portions reflect the optical beam with minimal beam divergence.  
     
     
         19 . The optical switch of  claim 7  further comprising a thermal isolation gap portion adjacent the fixed portion of the first and second paddle, where in the thermal isolation gap portion, the lower layer does not overlap the upper layer.  
     
     
         20 . The optical switch of  claim 9  further comprising: 
 a voltage supply for selectively providing electrical power to the resistive heating portions of the upper layers of the paddles;  
 a beam splitter disposed in the second propagation path for redirecting at least a portion of the optical beam into a third propagation path;  
 an optical detector disposed in the third propagation path for providing at least one beam position signal indicative of a position of the optical beam on the optical detector;  
 the voltage supply operable to adjust a characteristic of the electrical power provided to the resistive heating portions based on the beam position signal, such that the resistive heating portions generate more or less heat as determined by the beam position signal, thereby causing the first and second paddles to provide larger or smaller first and second deflection angles to thereby center the optical beam on the detector.  
 
     
     
         21 . An optical switching device for selectively transferring at least one optical beam between at least one first optical channel and M number of second optical channels, comprising: 
 a first optical structure for propagating the at least one optical beam along a first propagation path in a first propagation plane; and    a 1×M-dimensional array of optical switches, comprising: 
 M number of first switch portions adjacent to and aligned in parallel with the first propagation path, the first switch portions having substantially-planar first reflective surface portions that are operable to move in a first pitch plane between at least a first deflection angle and a second deflection angle, when at the first deflection angle, one of the first reflective surface portions for intercepting the optical beam propagating along the first propagation path in the first propagation plane and for reflecting the optical beam at a first reflection angle into an intermediate propagation path, and when at the second deflection angle, the first reflective surface portions not intercepting the optical beam; and  
 M number of second switch portions adjacent corresponding first switch portions, the second switch portions having substantially-planar second reflective surface portions, the second reflective surface portions operable to move in second pitch planes between at least the first deflection angle and the second deflection angle, the second pitch planes being substantially perpendicular to the first pitch plane, when at the first deflection angle, one of the second reflective surface portions operable to intercept the optical beam propagating along the intermediate propagation path and reflect the optical beam at a second reflection angle into one of M number of substantially parallel second propagation paths in a second propagation plane, the second propagation paths being substantially perpendicular to the first propagation path, and the second propagation plane being substantially parallel with the first propagation plane, and when at the second deflection angle, the second reflective surface portions not intercepting the optical beam; and  
   M number of second optical structures disposed in the second propagation plane, each of the second optical structures optically aligned with a corresponding one of the M number of second switch portions in a corresponding one of the M number of second propagation paths, each of the second optical structures operable to receive the optical beam from the corresponding one of the second reflective surface portions and direct the optical beam to a corresponding one of the M number of second optical channels.    
     
     
         22 . The optical switching device of  claim 21  wherein the first and second optical structures further comprise optical fibers.  
     
     
         23 . The optical switching device of  claim 21  wherein the first optical structure further comprises a modulated laser light source.  
     
     
         24 . The optical switching device of  claim 21  wherein the first optical structure further comprises a modulated light-emitting diode light source.  
     
     
         25 . The optical switching device of  claim 21  further comprising: 
 N number of the first optical structures for propagating N number of optical beams along N number of substantially parallel first propagation paths in the first propagation plane; and  
 N number of the 1×M-dimensional arrays of optical switches, each array aligned with a corresponding one of the N number of first propagation paths.  
 
     
     
         26 . The optical switching device of  claim 25  wherein the first optical structure, the array of optical switches, and the second optical structures are reciprocal devices, such that the optical beam may travel from the first optical structure through one of the optical switches and into one of the second optical structures, or from one of the second optical structures through one of the optical switches and into the first optical structure.