Takayasu Mochizuki

Performance of composite glass slab laser

Three-layer composite glass slab lasers were fabricated using optical contact and thermal fusion methods, and their characteristics were examined in an attempt to develop a high-peak-power glass laser able to deliver a high-quality beam at a high repetition rate operation. The optical characteristics, laser characteristics, and limitation of the output of these composite slabs and the monolithic slab are compared. It is found that thermal birefringence effects were reduced in the case of the composite slabs in comparison to the monolithic slab at the same output during repetitive operation, thereby maintaining a high level of beam quality. A doping amount of Nd/sub 2/O/sub 3/ of 6 wt.% was optimum for increasing the single pass gain of the composite slabs. An optimum thickness of doping layer exists for keeping gain high while maintaining thermal birefringence effects at a low level. >

Laser Excitation Effects on Laser Ablated Particles in Fabrication of High Tc Superconducting Thin Films

Improvement in the characteristics of YBa2Cu3Oy superconducting thin films was performed by a second laser irradiation method. Particles in the laser ablated plume were decomposed and/or excited by the second laser irradiation. By controlling a time delay of the second laser from the ablation laser, ablated particles with average velocities of 1×106 cm/s and 2×105 cm/s were irradiated with the second laser. Notable improvement was observed when the slower ablated particles were irradiated with the second laser.

Strong wavelength dependence of laser ablation fragments of superconductor YBa2Cu3Oy

In addition to the two groups of radiative fragments which have previously been described, two groups of nonradiative fragments are first observed in laser-ablated fragments of YBa2Cu3Oy, using a space/time-resolved optical transmittance measurement. The average velocities of the nonradiative fragments (2×105 cm/s and 2×104 cm/s) are much lower than those of the radiative fragments (5×106 cm/s and 1×106 cm/s). The yield of the nonradiative fragments increases with increasing laser wavelength, while that of the radiative fragments is nearly wavelength independent.

Development of optical fiber for medical Er:YAG laser

The Er:YAG laser beam has stronger absorbability by water than the CO2 laser beam. Therefore, the Er:YAG laser is expected to be used as the surgical treatment beam for water- rich biotissue. And if the effective optical fiber of 3 micrometers band is developed, it is also expected for use as an endoscopic beam. So we are doing investigations of the optical fiber for Er:YAG laser. The optical fibers used are fluoride glass, chalcogenide glass fibers, and the hollow tube guide. From our experimental results, these Er:YAG laser beam delivery techniques would be expected to perform well in practical use.

Infrared delivery systems for Er:YAG laser

Er:YAG laser beams (2.94 micrometers ) have more strong absorbability by water than CO2 laser beams (10.6 micrometers ). Er:Yag lasers are expected as a treatment beam for water rich biotissue, we considered the application of Er:YAG lasers for medical use in the near future. When applying it for medical use, the delivery systems must be prepared. So we are investigating higher pulse power Er:YAG laser beam transmission with fluoride glass fibers, chalcogenide glass fibers, and hollow tube guides. From our experimental results, these beam delivery techniques are possible for Er:YAG lasers.

Development Of High Power Solid State Lasers At HOYA Corp.

Several lasers are, or have been, developed at the HOYA Laser Laboratory: Conventional YAG-rod lasers, glass fiber bundle lasers and moving glass slab lasers. Slab lasers are considered the engineering answer to the demand of higher average power. We obtained 386 W with a moving glass slab laser. Parts of the program are also erbium doped YAG and glass lasers. We developed a stable and reliable 10-W output 3-μm Er:YAG laser. All models have been developed with a specific application in mind,