A fluorescent microdroplet was formed in elastomer to facilitate handling and wavelength tuning. A methanol solution of rhodamine 6G was put into a solidifying polysiloxane resin with a needle. Addition of surfactant was effective to stabilize the droplet. Being excited by a laser pulse (532 nm, > 50 microJ/mm(2), 5 ns), the droplet exhibited a whispering gallery mode emission in the 570-610 nm wavelength range. The resonance peaks shifted as the droplet diameter expanded by elastomer deformation.

We report an all-solid-state laser system that generates over 200 mW cw at 244 nm. An optically pumped semiconductor laser is internally frequency doubled to 488 nm. The 488 nm output is coupled to an external resonator, where it is converted to 244 nm using a CsLiB(6)O(10) (CLBO) crystal. The output power is limited by the available power at 488 nm, and no noticeable degradation in output power was observed over a period of several hours.

Cesium triborate (CsB3O5: CBO) crystal is an important nonlinear optical crystal for UV light generation. Although the crystals contain scattering centers, postgrowth quenching of the crystals is successful in reducing the scattering centers. After in-depth experimental analysis of the quenching process we propose the existence of retrograde solid solution region at high temperatures in CBO. Based on the retrograde solid solution curve we are able to reduce the scattering centers in CBO crystals by the vapor transport equilibration process. By our hypothesis we are able to explain the experimental results and mechanism of formation of scattering centers in CBO crystals.

By delaying the second pass of the pump of a singly resonant optical parametric oscillator, the conversion efficiency can be improved. We show the experimental results of an intracavity-doubled singly resonant parametric oscillator pumped by a Q-switched laser. Using 0.49 mJ of pump energy at 532 nm from a diode-pumped Nd:YAG laser, 0.085 mJ of 488 nm was obtained with the optimum delay for the second pass of the pump, giving a conversion efficiency of 17%. The improvement over the case of a single-pass pump was 85%, and the improvement over the double-pass pump with a small delay was 40%.