PHYS 416

There has been active interest in the production of Rugate filters in Porous Silicon (PS) for both their optical properties and their potential use as chemical sensors.  While most studies have centered on the production of a single-wavelength filter, a few studies have investigated the production of multiple wavelength filters.  The majority of these filters have been prepared by sequential electrochemical etchings under different current densities.  We report the simultaneous encoding of multiple frequencies as well as the encoding of reflectance amplitudes in PS Rugate filters in a single electrochemical etch.  Figure 1 illustrates the simultaneous encoding of a 4-wavelength Rugate filter whose current amplitudes were set at relative amplitudes of .25, .50, .75, and 1.00.  Experimental parameters for such a single electrochemical etch cycle will be presented and discussed.