Toshinori Ishida

6-kW and 10-kW high-power lamp-pumped MOPA Nd:YAG laser systems

High power lamp pumped YAG lasers of 6 kW and 10 kW average output power with good beam quality have been developed by using MOPA arrangement with multi-pump cavities for oscillator and amplifiers. For 6 kW laser system, efficient pump cavity for lessening thermally induced beam distortion effects has been designed, which realized output power greater than 700 W and M2 value less than 70. CW 3.5 kW has been realized from 5 cavity laser oscillator and CW 6.7 kW output power has been obtained by adding 5 cavity amplifier to the oscillator. During development, much amount of power of scattered and deformed light surrounding a main laser beam was observed for increased number of amplifiers. By applying spatial apertures between amplifiers, laser output beam quality has been improved to as good as M2 of 73 [beam parameter product (2 (omega) *2 (theta) ) :100 mm (DOT) mrad], enough for fiber (NA 0.15, (phi) 0.6 mm) delivery. Furthermore, 14-rod cavities, 10 kW Nd:YAG laser system, which can generate world-highest output power of 10 kW or more as a solid state laser, have been developed for thick plate processing with 137 mm (DOT) mrad (M2 approximately 101) beam parameter product. This laser system has achieved the transmission to 9 kW or more for (phi) 800 micrometer/NA 0.2 fiber.

Uniform Electron Cyclotron Resonance Plasma Generation for Precise ULSI Patterning

Microwave perturbation results in lower microwave absorption because of plasma vibrations and pulses in an electron cyclotron resonance (ECR) plasma. Moreover, the parabolic 875 G equimagnetic field and the nonuniform magnetic field gradient causes nonuniform microwave absorption. Then, magnetohydrodynamic (MHD) plasma instability is generated in the ECR plasma. Accurate control of magnetic field profiles and microwave conditions for uniform and efficient microwave absorption is essential to the achievement of stable ECR plasma generation for precise anisotropic etching.

High-performance, digitally power controlled mini-laser welder, specially designed for high precision spot welding of optical modules

Owing to the rapid progress in information technology, requirements for optical modules to be used in optical fiber communication systems are appreciably becoming sophisticated and demanding. To meet the stringent requirement for highly reliable and stable optical modules, we have specially developed a new laser-welder M800C, to realize low-distortion, high precision spot welding of optical modules.Our novel laser cavity, designed to have highly rigid structure and good heat dissipation to alleviate thermal strain, has realized high laser output power stability, less than +/−0.6% of standard deviation value (4.6% peak-to-peak in 14,400 shots) in cyclic environmental temperature test from 5 to 35 degrees Celsius. In addition, we have developed a new laser-pulse-energy-dividing device by utilizing simple polarization dependent beam attenuators based on optical polarization for highly balanced dividing ratio. It can equally divide incident beam into three beams with less than +/−1.0% error for the typical ou...

Multi-Coil System for Electron Cyclotron Resonance Plasma Generation

The authors have developed a new multi-coil system for electron cyclotron resonace (ECR) plasma generation. The features of this multi-coil system are precise magnetic field control and the capability of achieving compatibiliry with low magnetic field gradient and high magnetic field uniformity. A low gradient and high uniformity of magnetic field in the ECR region contribute to highly dense and highly uniform plasma generation. Therefore, etching characteristic improvement is expected. As compared with the conventional two-coil system, the present multi-coil system achieved improvement of magnetic field uniformity of more than 60% at a low magnetic field gradient less than 20 G/cm, ion current density of more than 25%, and ion current density uniformity of about 75% in Ar plasma.