Polymeric wavelength filters with polymer gratings

Wavelength filters with Bragg gratings are demonstrated based on low-loss polymer waveguides and high-refractive-index polymer gratings. Two kinds of fluorinated polymers, perfluorocyclobutane and fluorinated poly(arylene ethers) are used for the low-loss waveguide operating around the 1.55 mu m wavelength. The polymer grating is made of Resole, and it is successfully integrated in the polymer waveguides. In order to fabricate the Bragg gratings on the polymer waveguides, we use a phase mask and a Hg lamp in a mask aligner as the illuminating source instead of the laser. This method provides uniform gratings on a large area as well as the alignment capability. In the fabricated wavelength filters, the reflectivity at the Bragg wavelength is 30 dB, the 3 dB bandwidth is as narrow as 0.6 nm, and the insertion loss is 3.7 dB. (C) 1998 American Institute of Physics.