MINIATURE FABRY-PEROT INTERFEROMETER

A NOVEL APPLICATION IS PRESENTED FOR THE USE OF FABRY-PEROT INTERFEROMETRY AS AN ANGULAR SENSOR. THIS IS PARTICULARLY ATTRACTIVE BECAUSE THE ANGULAR SENSITIVITY OF A FABRY-PEROT INTERFEROMETER IS PROPORTIONAL TO THE WIDTH OF THE ETALON. HENCE, IT CAN BE MADE MORE SENSITIVE BY WIDENING THE ETALON. A 10 MM WIDE ETALON, FOR EXAMPLE, YIELDS A WHOLE FRINGE FOR EVERY 50 MICRO-RADIANS OF CHANGE IN THE ANGLE OF INCIDENCE AT A WAVELENGTH OF 0.63 MICRON. THIS ANGULAR SENSITIVITY CAN BE USED TO MEASURE SECONDARY PHENOMENA THAT INDUCE ROTATION SUCH AS VIBRATION AND ACCELERATION. CONVENTIONAL FABRY-PEROT ETALONS ARE POLISHED SLABS OF GLASSWHOSE FLATNESS AND PARALLELISM ARE MAINTAINED TO A HIGH DEGREE OF TOLERANCE. THIS PROCESS IS COSTLY AND TIME CONSUMING. WE PRESENT AN ALTERNATIVE WAY OF FABRICATING FABRY-PEROT ETALONS WITH THE USE OF WAVEGUIDE MICROFABRICATION TECHNOLOGY. THERE ARE DISTINCT ECONOMIC ADVANTAGES TO THIS APPROACH BECAUSE THE RESULTANT MICRO-SENSOR WILL BE CHEAPER THAN THE CONVENTIONAL ONE WHEN MASS-PRODUCED. WE AIM AT DETERMINING THE EFFECTIVENESS OF THE MICROFABRICATION TECHNIQUES AT PRODUCING SEMICONDUCTOR MICRO-ETALONS WHOSE PERFORMANCE IS COMPARABLE TO THAT OF THEGLASS ONES. LITHOGRAPHIC TECHNIQUES WILL BE USED TO DEFINE THE ETALONS ON THE WAVEGUIDE STRUCTURE. THE NEW CONFIGURATION WILL ALLOW THE ANGLE OF PROPAGATION INSIDE THEWAVEGUIDE TO VARY CONTINUOUSLY SO THAT IT CAN BE USED AS AN ANGULAR SENSOR.