UV-written long-period gratings on polymer waveguides

We report an ultraviolet (UV)-writing technique for the fabrication of a long-period waveguide grating on a benzocyclobutene ridge waveguide coated with epoxy (UV 11-3), where the grating is formed by exposing the waveguide to 248-nm UV pulses emitted from a KrF excimer laser through an amplitude mask. The UV pulses produce both index modulation and corrugation on the epoxy cladding, and their combined effect gives rise to the observed transmission spectrum. We also highlight the effects of UV-induced nonuniformity along the grating by simulation and measure the temperature sensitivity of the resonance wavelength of the grating.