Compound Bragg reflection filters made by spatial frequency doubling lithography

A report is presented on the fabrication of complex Bragg filters with resonant wavelengths near 1.55 μm, patterned by photolithography using a high-resolution deep ultraviolet stepper. The projection of gratings with quarter-micrometer 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 five Bragg reflectors of different wavelengths, a quarter-wave shifted resonator, broadband stacked filters with as many as 15 uniform Bragg reflector sections of different Bragg wavelengths, and broadband stacked filters containing a passband within the reflection band. The filters exhibited nearly ideal spectral behavior