their polarization dependence. Our results clearly show the possibility of achieving polarization-insensitive operation in the presence of stress-induced birefringence and that the polarizationinsensitive condition can be maintained over a wide range of temperature. A temperature sensitivity of Ϫ0.14 nm/°C for the Bragg wavelength was obtained with an epoxy-clad Bragg grating, which is an order of magnitude larger than the value achieved with a fiber Bragg grating or a Bragg grating fabricated on a silica waveguide [12, 13]. Realization of tunable polarization-insensitive filters with Bragg gratings fabricated in simple polymer waveguide structures is promising.