Shuichi Fujikawa

Stabilization of a high-power diode-side-pumped intracavity-frequency-doubled CW Nd:YAG laser by compensating for thermal lensing of a KTP crystal and Nd:YAG rods

We have analyzed the stability of a high-power diode-side-pumped intracavity-frequency-doubled CW Nd:YAG laser. It is found that large green power fluctuations observed experimentally are suppressed by compensating thermal lensing of the nonlinear crystal KTP and that of the Nd:YAG rods with an advanced resonator design. Stable CW green powers of 27 W with a beam quality of M/sup 2/=8 and 16 W with M/sup 2/=1.2 (TEM/sub 00/-mode) were generated.

All-solid-state 5-kHz 0.2-TW Ti:sapphire laser system.

We have developed an all-solid-state 5-kHz Ti:sapphire Laser System, which produces 22-fs, 0.2-TW pulses. An average power of 22.2 W is the highest ever obtained in ultrashort laser sources. The serious thermal lensing due to high power pumping in a small area of the Ti:sapphire crystal is controlled successfully by a stable quasi-cavity with two concave mirrors.

20-W, 10-kHz UV beam generation by an all-solid-state laser

Highest 266-nm UV power, to our knowledge, of 20-W was generated by an all-solid-state laser with a high-quality CLBO crystal.

High-reliable high-power 266-nm UV beam generation by using high-quality uniform CLBO crystals with an all-solid-state laser

Summary form only given. High-power all-solid-state UV lasers are used for precise material processing applications in industrial fields with the potential advantage in the maintenance cost compared with other UV lasers. Industrial precise processing applications such as drilling on printed circuit board or cutting printed circuits require more than 10 W of UV powers at kHz-repetition. Authors have generated 266-nm UV power up to 20.5 W with the repetition rate of 10 kHz by fourth harmonic generation of an all-solid-state laser. However, the variation of UV powers with CsLiB/sub 6/O/sub 10/ (CLBO) crystals has not been discussed. We report on the high-reliable higher-power UV beam generation by using high-quality uniform CLBO crystals and a high-brightness high-power all-solid-state green laser.

High-power high-efficient diode-side-pumped Nd: YAG laser

We have demonstrated high-power and high-efficient performance of a cw Nd: YAG laser with simple and scalable side-pumping coxQuration. The “um output power of 147 W was obtained with the electric efficiency of 14.8 %. Ths is to our knowledge, the highest efficiency reported for diode-side-pumped Nd: YAG lasers. High-brightness operation was also camed out by applying bifocusing compensation of the Nd: YAG md. The best beam quality of M2 = 5.9 was obtained with the output power of 107 W. The brightness is calculated to be 272 MW/cm2sr.

1-kW high-quality beam generation from a diode-side-pumped Nd:YAG rod laser

We demonstrated a power scaling of Nd: YAG rod laser by cascaded-coupling of two identical bifocusing compensation resonators. The maximum output power of 1030 W was achieved with the beam quality of M2 = 9. The corresponding electrical-to-optical efficiency was 23 %.

Efficient high-beam-quality operation by use of a diode-stacks-side-pumped quasi-cw Nd:YAG laser

Laser power over 500W was obtained with the beam quality factor M2=4 and high electrical-to-optical efficiency over 20% by using two diode-stacks-side-pumped modules. The electrical-to-optical efficiency of 28% was achieved with single module operation.

Highly efficient diode-pumped 300-W Nd:YAG rod laser

Laser power of cw-329-W was generated with the optical efficiency of 41.1% and the electric efficiency of 18.8%. The laser also generated cw-118-W in TEM00 mode.

High brightness 127 W green beam generation by intracavity-frequency-doubling of diode-pumped Nd:YAG laser

Summary form only given. High average power green lasers based on intracavity-doubling of diode pumped solid-state-lasers are of considerable current interest because of their compact design and efficient performance for numerous applications, such as Ti sapphire laser pumping, 4th harmonic generation. Although, several papers reported over >100 W green power generation, their beam quality factors are M/sup 2/>19, thus the green beams are not adequate in particular for 4th harmonic generation. In this work, we present a high-brightness green laser system that generates up to 127 W green power, with the beam quality of M/sup 2/<9.

High-average-power, high-repetition, diode-pumped third-harmonic Nd:YAG laser

Summary form only given. Ultraviolet or visible frequency converted diode-pumped solid-state laser is one of the most promising candidates for drilling or trimming of printed circuit boards. To achieve higher throughput, it is essential to enhance average output power at high repetition frequency. Although, more than 20 W 351-nm average output power has been reported with an intracavity-frequency-tripled Nd:YLF laser, its pulse repetition frequency was 2.5 kHz, and average output power of high repetition 355-nm beam sources were limited at a level of 5 W. We enhanced the average output power of a third harmonic Nd:YAG laser up to 18 W, at the repetition rate of 25 kHz. This is what we believe to be the highest number obtained with extracavity-frequency-converted solid-state lasers.