Toshifumi Yokoyama

Miniaturized Blue Laser using Second Harmonic Generation

We demonstrate a miniaturized blue laser (5×12×1.5 mm3) using second harmonic generation (SHG), which consists of a quasi-phase-matched (QPM)-SHG waveguide device on an x-cut Mg-doped LiNbO3 substrate and a tunable distributed-Bragg-reflector (DBR) laser diode. By using the QPM-SHG waveguide device on an x-cut substrate, efficient optical coupling was realized without a half-wave plate, and the maximum coupling efficiency of 75% was achieved. The blue light power of 2 mW was generated for the fundamental coupling power of 20 mW, which agreed with a conversion efficiency of 10%. The mechanical stability of the planar-type butt-coupled SHG blue laser was examined, where the coupling efficiency was maintained constantly under the change of module temperature and the temperature cycle test from 10 to 60°C. We succeeded in downsizing the SHG blue laser to 0.1 cm3, which is sufficiently small for its application to optical disk systems.

Compact Intracavity Green Light Source with Wide Operation Temperature Range Using Periodically Poled Mg:LiNbO3

A compact and high power green-light source has been developed in diode-pumped solid-state laser based on periodically poled Mg:LiNbO3 (PPMgLN). Optimization of the PPMgLN length in Nd:YVO4 intracvity can achieve wide operation temperature range over 30 °C with maintaining high conversion efficiency. Based on this result, we demonstrated 3 cm3 laser module which generated continuous-wave 0.7-W green light with wall-plug efficiency as high as 11.8%.

L‐9: Late‐News Paper: Laser Projection Display with Low Electric Consumption and Wide Color Gamut by Using Efficient Green SHG Laser and New Illumination Optics

air-cooled RGB lasers including a compact and efficient green SHG laser and new illumination optics for speckle noise reduction, we developed advanced laser projection engine. A prototype of laser rear projection display with low electric consumption (about 50W) for light sources and wide color gamut (137%NTSC) was realized. 1. Introduction the last decade, several different micro-display technologies (LCD, DMD and LCOS) have been developed and projection displays captured the large screen market for business and home theater. Most projection displays are now using lamps as light sources, such as high-pressure mercury lamps and metal halide lamps. Laser light sources are attractive for projection displays. Projection displays based on RGB lasers can provide extremely wide color expression with the narrow spectrum of lasers. Due to small etendue, laser lights are projected with high efficiency. Lasers have longer life time and faster response time than lamps. As high brightness and high power efficiency of lasers contribute to downsizing systems and improving electric efficiency, laser projection displays will find wide applications (1-3). However, for realizing laser displays there are two problems. The one is a suitable green laser with high efficiency, high power and compact size. As there are no green diode lasers and conventional green lasers for high output power need big mechanisms such as water-cooling devices, it is difficult to downsize and to decrease electric consumption. The other problem is an interference phenomenon called speckle. As lasers have high coherency, speckle noises are superposed on projected images (4). We overcome these problems and demonstrate a laser rear projection display with low electric consumption.

New Passive Alignment Method of Channel Waveguide Device Using Height Control Spacers

We realized a high coupling efficiency of a laser diode and a channel waveguide device using a new effective alignment method. We adopted the new passive alignment method which involved the use of height control spacers to adjust the vertical position and an image processing technique to adjust the horizontal position. We examined the assembly of a planar module that consists of a laser diode and a channel waveguide device. Coupling efficiency of over 70% of the maximum coupling efficiency was achieved in every sample.