Akihiro Takami

High-power operation of broad-area laser diodes with GaAs and AlGaAs single quantum wells for Nd:YAG laser pumping

The dependencies of the main lasing characteristics on the facet reflectivity for GaAs and AlGaAs single-quantum-well (SQW) separate-confinement heterostructure (SCH) broad-area laser diodes (LDs) are analyzed. Conditions for the facet reflectivity to achieve optimum values are identified. Under these conditions, the authors obtained respective maximum output powers of 2.9 and 2.6 W for GaAs-SQW and AlGaAs-SQW single-stripe LDs for 150 mu m stripe width, lasing at about 808 nm under a continuous-wave (CW) condition. These LDs were stably operated for over 2000 h under the condition of 1 W constant output power with automatic power control circuits at 45 degrees C in CW operation. >

High-power 780 nm window diffusion stripe laser diodes fabricated by an open-tube two-step diffusion technique

High-power and low-threshold-current GaAlAs lasers with a simple window structure fabricated by controllable open-tube two-step diffusion and single-step metalorganic chemical vapor deposition are discussed. The window structure and the waveguide with a narrow width around 2 mu m are formed by diffusion of zinc, which just passes through an n-type active layer. CW output power up to 134 mW without catastrophic damage and a threshold current of 17 mA have been achieved. A maximum output power density of 16 MW/cm/sup 2/ is estimated. A stable fundamental transverse mode of up to 100 mV in the wavelength range of 780 nm is obtained. Excellent uniformity of device characteristics is confirmed. >

High-power operation of AlGaAs SQW-SCH broad-area laser diodes for Nd:YAG solid-state laser pumping

AlGaAs single-quantum-well separate-confinement-heterostructure (SQW-SCH) single-stripe broad-area laser diodes (LDs) for Nd:YAG solid-state laser pumping were developed. The high-power operation of the SQW-SCH LD was demonstrated. The maximum output power under continuous wave operation at room temperature was 2.6 W in the range of the Nd:YAG absorption band. Stable operation was also confirmed for over 500 h under the condition of 25 degrees C at 1 W under continuous-wave operation.<<ETX>>

Thickness dependence of defect density in thin film silicon formed on insulator polycrystalline by zone-melting recrystallization [solar cells]

Formation technique of high quality thin film polycrystalline Si on insulator by zone-melting recrystallization (ZMR) was investigated for use in Si solar cell applications. Varying the thickness of polycrystalline Si of ZMR samples, thickness dependence of defect density in ZMR-Si films was studied. It was found that defect density of ZMR-Si film was strongly affected by thickness of polycrystalline Si. By thinning the polycrystalline Si film, defect density of ZMR-Si film was reduced to 3/spl times/10/sup 6//cm/sup 2/ without lowering scanning speed at ZMR process.