High-power blue/violet QPM-SHG laser using a new ridge-type waveguide

Abstract

Summary form only given. Compact blue/violet light sources with high-power, low-noise and diffraction-limited focusing beam are required to realize high-density optical disk systems. A second-harmonic generation (SHG) laser has advantages principally in the noise and beam quality compared with another candidate, the GaN laser. The quasi-phasematched (QPM) SHG device is usually fabricated by forming a proton-exchanged waveguide on a periodically domain-inverted MgO:LiNbO/sub 3/ substrate. However, the proton-exchanged waveguide presents disadvantages such as a graded index profile, asymmetric modes and degraded nonlinear property. Therefore, a new waveguide technology to replace the proton-exchange method is desired to realize efficient and high-power SHG lasers. We focus on the machining technique for processing three-dimensional waveguides which can draw out the original performance of nonlinear crystals. We propose a new ridge-type waveguide QPM-SHG device fabricated by ultraprecision, machining, and demonstrate high-power blue/violet light generation of 100 mW using the Ti:Al/sub 2/O/sub 3/ laser as a fundamental source and 14 mW output by frequency doubling of the laser diode (LD).