Takunori Taira

Optical absorption and emission spectroscopy of Nd:Bi4Si3O12 grown by Bridgeman method

Up to 5.0 at.% Nd3+ doped Bi4Si3O12 single crystals were realized by the Bridgman method. The spectroscopic parameters were evaluated and found that Nd3+:Bi4Si3O12 has a large quenching parameter (3.6 at.%) and very wide bandwidth in both transition of emission (23.1 nm) and absorption (16.1 nm). These properties are suitable for diode- pumped solid state lasers.

Output beam characteristics of a Nd:YVO4 miniature laser

The output beam characteristics of a CW diode end-pumped miniature Nd:YVO4 laser (1.1 at.%, 1 X 3 X 3 mm3) operating in fundamental and SHG regime are presented. Using M2 factor to describe the multimode pump beams propagation from the broad-emission-area diode-laser the coupling optics was designed to obtain a high value for the mode-matching efficiency. A maximum slope efficiency of (eta) s equals 58.6%, with (eta) 0 equals 53.8% optically efficiency at maximum pump power, characterized a laser resonator of 50 mm length in transversal TEM00 mode. In the SHG experiments using a KTP crystal a maximum power of 100 mW was reach in a circular laser beam of 4.2 mrad half-angle divergence.

Influence of active-medium properties on high-power solid state laser beam characteristics

In order to describe the transversal mode construction in a real laser resonator, a mathematical model was investigated. The analysis use Kirchhoff-Fresnel diffraction equation and amplification processes in the active medium, that was supposed as sum of thin discs with gain and losses constants on every discs length. Influence of additional phenomenon on laser beam characteristics, as phase-shift caused by active medium thermal induced refractive power and curvature of the resonator mirrors were considered.

High-power Q-switched and frequency-doubled Nd: YVO4 miniature lasers

We have studied the electro-optic Q-switching on a frequency doubling KTP crystal. It is possible to achieve approximately 1 kW, 6 - 8 ns green pulse generation on diode pumped Nd:YVO4 miniature lasers.