Toshinori Yagi

CW 20-kW SAGE CO/sub 2/ laser for industrial use

A CW CO/sub 2/ laser with power output of more than 20 kW is described. The laser consists of a discharge excitation system named SAGE (Silent-discharge Assisted Glow discharge Excitation) and a ZnSe or KCl transmissive window for extracting high-quality beams with axisymmetric intensity profile from a confocal positive-branch unstable resonator. SAGE is effective in forming a uniformly distributed and stable discharge in a large-volume, high-pressure gas excitation medium. Together with appropriate high-pressure gas conditions and a properly selected zeolite to adsorb water vapor in the laser chamber, the transmissive windows enable gas-sealed operations. The structure of the 20-kW SAGE laser and its performance characteristics are described. The maximum CW power of 26.5 kW with an efficiency of 16.5% is attained with the ZnSe window, and a 20.3-kW power output is extracted through the KCl window. Long-term gas-sealed operation at a CW power level of 20 kW has been demonstrated for a period of 65 h. >

High-power operation of AlGaInP red laser diode for display applications

Substantial limitation of output power in AlGaInP based red broad area (BA) laser diode (LD) originates from an electron thermal overflow from an active layer to a p-cladding layer and fatal failure due to catastrophic optical mirror degradation during the LD operation. New red BA-LD was designed and fabricated. The LD chip had triple emitters in one chip with each stripe width of 60 um, and was assembled on Φ9.0 mm -TO package. The LD emitted exceeding 5.5 W at heat sink temperature of 25 °C and 3.8W at 45 °C under pulsed operation with frequency of 120Hz and duty of 30%, although the current product, which has a 40 um single emitter chip assembled on Φ5.6mm –TO, does 2.0 W at 25 °C. The lasing wavelength at 25 °C and 2.5W output was 638.6 nm. The preliminary aging test under the condition with the operation current of 3.56A, CW, auto-current-control mode (ACC), and the heat sink temperature of 20 °C (almost equal to the output of 3.5 W) indicated that the MTTF due to COMD was longer than 6,600 hours under CW, 22,000 hours under the pulse with duty of 30%.

Energy-efficient optical system for excimer laser ablation apparatus

To improve the capabilities of excimer laser ablation processing apparatus, we have been developing an innovative Multiple Irradiation Optical System (multiple irradiator). In this system, we placed a reflector opposite the mask, and used a mask with a highly reflective coating. The laser beams therefore irradiate the mask repeatedly, and we can use the laser energy more efficiently than conventional optical systems. The experimental results show that our system is 12 times more energy efficient than the conventional optical systems. Also, we have made a prototype excimer laser material processing apparatus with the multiple irradiator, which is suitable for drilling viaholes of less than 100 micrometers diameters such as viaholes of print circuit boards. The processing speed is less than 1 minute when the material is 100 mm X 100 mm wide and 25 micrometers thicknesses polyimide film, and the laser energy is 40 mJ/shot with 600 Hz frequency.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Reliability study on high power 638-nm triple emitter broad area laser diode

Reliabilities of the 638-nm triple emitter broad area laser diode (BA-LD) with the window-mirror structure were studied. Methodology to estimate mean time to failure (MTTF) due to catastrophic optical mirror degradation (COMD) in reasonable aging duration was newly proposed. Power at which the LD failed due to COMD (PCOMD) was measured for the aged LDs under the several aging conditions. It was revealed that the PCOMD was proportional to logarithm of aging duration, and MTTF due to COMD (MTTF(COMD)) could be estimated by using this relation. MTTF(COMD) estimated by the methodology with the aging duration of approximately 2,000 hours was consistent with that estimated by the long term aging. By using this methodology, the MTTF of the BA-LD was estimated exceeding 100,000 hours under the output of 2.5 W, duty cycles of 30% .