Katsuhiko Komatsu

Time-resolved spectroscopic study of high-pressure self-sustained discharge-pumped atomic xenon lasers

To explore the lasing kinetics of UV-preionized, self-sustained discharge-pumped atomic xenon (5d to 6p) lasers, the time-resolved spectroscopy of the laser output from the multiline laser resonator is reported. The dilutents used were Ar and He. Increasing Xe concentration shortened the 1.73- mu m laser pulse duration and decreased the total (multiline) laser output energy, because increased Xe metastable state population contributes to the increase of the 6p state population (lower laser level) by electron-impact excitation and radiation trapping during discharge pumping. High-excitation-rate pumping resulted in the decrease of the laser output power of 1.73- and 2.63- mu m lines. Increasing the total gas pressure leads to high-efficiency operation due to modest-excitation-rate pumping at high pressures. >

Gain measurements of high‐pressure ultraviolet‐preionized self‐sustained discharge pumped atomic xenon laser

To explore the laser kinetics of atomic xenon lasers pumped by an ultraviolet‐preionized, self‐sustained discharge, time‐resolved small‐signal gains are measured using a long‐pulse probe laser. Faster electron mixing processes among excited xenon manifolds in the 6p state may affect the small‐signal gain distribution among 1.73, 2.03, and 2.65 μm laser lines, which share the same upper laser level Xe(5d[3/2]1) at excitation rates in excess of 160 kW/cm3. When the excitation rate in a late part of the discharge is increased, absorption caused by repumping of the lower laser level is observed at 1.73 μm. The measured gains are discussed in conjunction with multiline laser oscillation performance obtained by the same laser device.

Subsonic TE N 2 -Co Mixing Laser

CO lasers have the advantages of high power and high efficiency. The electrical conversion efficiency is remarkably high and the value of 47% was achieved with the coaxial flow CO laser at a wall temperature of 77 K 1. CO lasers are, however, not commercially used to date because a temperature below 100 K is necessary in order to achieve such high efficiency. Although the operation of CO lasers at room temperature is also possible, the conversion efficiency is as low as 15%. It is well known that the addition of N2 effective to increase the output performance of the CO laser operating near room temperature1,2. For the coaxial flow lasers the concentration of N2 is limited. And high N2 concentration is achieved in supersonic flow and pulsed CO lasers. The latter two types operate for short durations, and the effect of the addition of N2 is supposed to be the optimization of E/N values of the discharge,2 rather than the vibration to vibration (V-V) energy transfer between N2 to CO, because the N2-CO V-V transfer rate is twice as small in magnitude as the CO-CO V-V transfer.

Japanese CELRAP laser fabrication: optimized Czochralski growth conditions and fundamental properties of Ho/sup 3+/ doped Lu/sub 3/Al/sub 5/O/sub 12/ crystals

The optimum Czochralski growth conditions of Ho/sup 3+/ doped Lu/sub 3/Al/sub 5/O/sub 12/ laser crystals are experimentally verified. The effective distribution coefficient of Ho/sup 3+/, and some optical (fluorescence and absorption spectra) and thermal properties (thermal conductivity) of the crystal are measured.

Japanese CELRAP laser radar: obstacle warning avoidance function

The obstacle warning avoidance function of the Japanese CELRAP laser radar system is verified based on the return signal measurements using wires as targets under various conditions. The system applicability for the function is successfully confirmed.

Japanese CELRAP laser radar design considerations and its performance

The Japanese system fabricated and being tested under the US-Japan Cooperative Eyesafe Laser Radar Project (CELRAP) between the US Army and Japan Defense Agency is summarized. Some technologies obtained and system performance measured are presented.

Japanese CELRAP laser fabrication: high power, strained InGaAs-InGaAsP-InP quantum-well lasers emitting at 1.9-/spl mu/m

High power InGaAs-InGaAsP-InP quantum-well lasers operating at 1.9-/spl mu/m are fabricated and evaluated. Eight 2-stripe array lasers are stacked to achieve 8 W CW output power with a maximum power efficiency of 11.2% at 5 W operation.