Muneyuki Nishioka

Improvement in UV Optical Properties of CsLiB6O10 by Reducing Water Molecules in the Crystal

We investigated the effects of water molecules in CsLiB6O10 (CLBO) crystals on UV optical properties. Our results show that long-term heat treatment is necessary to adequately remove water molecules from inside the crystal. The reducing the number of water molecules contained in the crystal improves the transmittance at 266 nm. In addition, the long-term heat-treated crystal can generate three-times higher 266-nm output without bulk damage than a normal sample.

Growth of high-quality CsLiB6O10 crystals from materials mixed in aqueous Solution

CsLiB6O10 crystals were grown from high-quality sintered powder using the Top-Seeded Solution Growth (TSSG) method. The starting materials were prepared by calcination via a homogeneous precursor mixed in aqueous solution. The crystal grown possessed approximately a two-fold higher bulk ultraviolet laser-induced damage threshold than conventional crystals and fused quartz. The IR absorption intensity due to hydroxyl ions in the crystal was revealed to be almost the same as that in conventional crystals.

Crystal growth of CsLiB 6 O 10 in dry atmosphere

We attempted to grow CLBO crystals in dry atmophere. We estimated the OH impurities in the crystal by non-polarized Fourier transform infrared spectrometer and measured the laser damage tolerance by 266-nm high repetition pulse laser.

Investigation of bulk laser damage and absorption of laser light in CsLiB6O10 crystals (Abstract Only)

High-power solid-state ultraviolet (UV) lasers by using a have been in high demand because of their convenient operation procedure. An effective technique for UV generation is cascaded sum-frequency generation pumped by the output of near-IR solids-state lasers. The performance of such solid-state UV lasers appears to depend on the ability and reliability of nonlinear optical (NLO) crystals that are employed for laser frequency conversion. Discovery of CsLiB6O10(CLBO) crystals have enabled the production of such practical high-power all solid-state UV lasers. In 2001, UV output power up to 23.0 W by fourth harmonic generation of Nd:YAG laser was achieved. It is fact that laser-induced damage of NLO crystal is a limiting factor on reliable operation of high-power solid-state UV lasers. Bulk laser-induced damage of NLO crystal is related to the crystals quality. In this paper, we have investigated the relationship among the bulk laser-induced damage threshold (LIDT), dislocation density and absorption of laser light in CLBO crystals with various crystallinity. The bulk LIDT of CLBO increased with decreasing dislocation density. High-quality crystals with a higher LIDT (15 - 18 GW/cm2) have a lower dislocation density of 6.6 x 103/cm2 than that of conventional CLBO (~15.0 x 103/cm2). The relationships between crystal quality and absorption of laser light will be presented.

Influence of crystallinity on the bulk laser-induced damage threshold in CsLiB/sub 6/O/sub 10/ for high-power UV laser source

Crystallinity of CLBO could be drastically improved by solution-stirring TSSG method. They possessed high bulk and surface laser-induced damage thresholds, and the qualities were adequately uniform throughout the crystals. 40-W 266-nm output was obtained by using these high-quality crystals.