Koichi Kusukame

Second Harmonic Generation with High Conversion Efficiency and Wide Temperature Tolerance by Multi-Pass Scheme

We proposed a multi-pass second harmonic generation scheme in which condensed fundamental light passed through a nonlinear crystal many times. The multi-pass scheme was realized by using a wide periodically-poled MgO:LiNbO3, concave mirrors and condensing optics. The total wavelength conversion efficiency of the multi-pass scheme was increased because non-converted fundamental light which had passed through the nonlinear crystal was re-injected and condensed into the nonlinear crystal and converted. Moreover the total temperature tolerance of the multi passes was widened because the fundamental beam passes had different phase-matching temperature and compensated for miss conversions of other passes. In this work, continuous-wave 5 W green light (532 nm) with 66% conversion efficiency and wide temperature tolerance were obtained.

20.3: A Bright and Efficient Mobile Projector Using a Compact Green Laser

We have developed an ideal W-class compact green laser for mobile projectors. The wall-plug efficiency of the laser was higher than 15% over wide temperature range. By using RGB lasers and small LCOS projection optics, a mobile projector with high brightness (100 lm) and excellent efficiency (20 lm/W) was demonstrated.