A long-period fiber grating (LPFG) humidity sensor is reported utilizing poly(ethylene oxide)∕cobalt chloride (PEO/CoCl₂) as a hybrid hygrosensitive cladding coating. A thin overlay of the material is deposited on the LPFG and with exposure to different ambient humidity levels, its spectral properties are modified. The material parameters associated with the sensing mechanism may include those of refractive index, absorption, and morphological alterations of the overlaid material. Relative humidity variations in the range from 50% to 95% have been detected with a resolution better than 0.2%. The response time constant of the fiber sensor is of the order of a few hundred milliseconds.

We document the lasing performance of a waveguiding layer of Ti:sapphire, of $\sim 12-\mathit{\mu }\mathrm{m}$ thickness, grown by pulsed laser deposition from a 0.12–wt. % Ti₂O₃ Ti:sapphire single-crystal target onto an undoped $z$-cut sapphire substrate. Lasing around 800 nm is observed when the waveguide layer is pumped by an argon-ion laser running on all-blue-green lines, with an absorbed power threshold of 0.56 W, with high-reflectivity $\left(R>98\%\right)$ mirrors. With a 5% pump duty cycle and a $T=35\%$ output coupler, a slope efficiency of 26% with respect to absorbed power is obtained, giving quasi-cw output powers in excess of 350 mW.