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Slab optical waveguides made of ''hot-embossing-able'' phenyl and methyl silsesquioxane were fabricated. A wide range of refractive index control, from 1.46 to 1.56 at 0.63 mm was attained with high-precision controllability of precursor composition, AE0:5 Â 10 À3 . A low birefringence, less than 7 Â 10 À4 , was obtained. Despite the low birefringence, the refractive index of the waveguide was constant after heating at 200 C in an oxidizing atmosphere for 500 h. No difference in refractive index against the prolonged exposure of damp heating at 90 C and 90% relative humidity for 780 h was obtained. Radiative striation due to spin coating was successfully eliminated with planarization of the waveguide with hot embossment using a planar mold. The propagation loss of the planarized slab waveguide was measured to be less than 0.10 dB/cm at 0.63 mm of the transverse-electric mode. This material is considered to be suited for use in a cost-effective waveguide device.

We demonstrate an all-fiber Q-switched laser operation in the 2 µm region on the basis of a dynamic periodic microbend and pulsed-pump configuration. A single-mode thulium-doped silica fiber is pumped by 1.6 µm-band laser diodes, and the dynamic loss is introduced in the fiber ring resonator by the periodic microbend that is electrically controlled with a piezoelectric actuator. When the voltage-off period of the piezoelectric actuator is set at 20 µs for the pump power of 120 mW, the output pulse power is measured by 420 mW with a pulse width of 1.3 µs.

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