UV-laser 조사에 따른 폴리머 상부 클래드 광도파로 브래그 격자의 파장 변화

The wavelength shift of waveguide Bragg grating with its polymer overclad irradiated by UV-laser

The UV laser trimming can be useful to have an accurate performance specification of the passive waveguide devices. In order to measure the change of the refractive index of polymer overclad layer under the irradiation of uv light in a high precision Bragg grating is fabricated on the silica core of planar waveguide and the corresponding transmittance spectrum was analyzed. An effective refractive index change of $4.7x10^{-5}$ was obtained for a straight waveguide when its $60{\mu}m$-thick overclad was irradiated by UV laser pulses of its total fluence 24 $J/cm^2$.