Miniature blue-green laser source using second-harmonic generation

摘要

Apparatus and method for producing coherent blue-green-light radiation having a wavelength of essentially 490-500 nm. A diode laser, such as a strained-layer InGaAs/GaAs diode laser, provides a 980-1,000 nm beam, and a nonlinear crystal of KTP produces coherent radiation by noncritically phase-matched second-harmonic generation (SHG) of said beam. The beam preferably has a wavelength of essentially 994 nm for generating radiation having a wavelength of essentially 497 nm. The crystal is disposed within an optical resonator and the frequency of the laser is locked to that of the resonator. Alternatively, two diode lasers are oriented to provide orthogonally polarized beams each with a wavelength of 980-1,000 nm but within essentially 1 nm of each other, and the KTP crystal is oriented with its a- and c-axis parallel to the orthogonally polarized beams. The KTP crystal may have an associated optical waveguide along which the beam is propagated to enhance SHG efficiency.