Refractive index change by photoinduction of a UV-sensitive SMF-to-PWG coupler

We fabricated a UV-sensitive photofunctional device using evanescent field coupling between a side-polished single-mode optical fiber (SMF) and photochromic dye-dispersed polymer planar waveguide (PWG). PWG was made by diarylethene derivative [1,2-bis(2,5-dimethylthiophen-3-yl) hexafluoro-cyclopentene (DM-BTE)] with a stability and memory effect by photoinduction. The wavelength response characteristic for UV irradiation time was 3.44 nm (UV irradiation time 60 s), and recovery time was 140 s. The optical attenuation characteristic of 1310-nm wavelength was 0.4 dB in 1 wt% concentration of DM-BTE and 1.65 dB at 10 wt% DM-BTE. The refractive index changes of DM-BTE by photoinduction were /spl Delta/n=0.00067 in the condition of 3 wt% of DM-BTE concentration and 5 mW of UV intensity and 70 s of UV irradiation time.