Compound Bragg Reflection Filters Made By Spatial Frequency Doubling Lithography.

We report fabrication of complex Bragg filters with resonant wavelengths near 1.55 microns patterned by photolithography using a high resolution deep ultraviolet stepper. The projection of gratings with quarter micron features was made possible by the use of spatial frequency doubling lithography. A single chip, processed entirely in the silicon facility, was used to demonstrate 5 Bragg reflectors of different wavelength, a quarter wave shifted resonator, broad band stacked filters with as many as 15 uniform Bragg reflector sections of different Bragg wavelengths and broad band stacked filters containing a pass band within the reflection band. The filters exhibited nearly ideal spectral behavior.