Polymeric waveguide wavelength filters using electron-beam direct writing

Polymeric waveguide wavelength filters based on a low-loss negative tone epoxy Novolak resin polymer have been fabricated using electron-beam direct writing. Both the waveguides and the gratings were exposed simultaneously, which effectively eliminate the alignment errors that can be generated during fabrication. A first-order Bragg grating around 1550 nm wavelength was used, and a transmission peak of - 27 dB was obtained with a 5 mm long grating length, corresponding to >99% reflection. The 3 dB transmission bandwidth was found to be ∼0.8 nm and the 10 dB bandwidth was ∼ 1.0 nm. Dependence of the Bragg wavelength on electron-beam dosage and waveguide width was also investigated.