Tunable polymer waveguide Bragg filter fabricated by direct patterning of UV-curable polymer

Tunable polymer wavelength filters are demonstrated using a silicon-nitride grating which gives high refractive index contrast with polymers. The polymer waveguides are defined using direct patterning of a liquid-state UV-curable polymer by proximate-contact lithography technique. The wavelength filter exhibits a narrow bandwidth of less than 1.0 nm and a transmission dip of more than −15 dB. The peak wavelength is shifted over 10 nm in the temperature range of 25-70 °C and the thermal tuning efficiency is −0.212 nm/°C.