Highly efficient quasi-phase-matched second-harmonic generation by frequency doubling of a high-frequency superimposed laser diode

A numerical scheme for nonlinear Helmholtz equations with strong nonlinear optical effects

A numerical scheme is presented to solve the nonlinear Helmholtz (NLH) equation modeling second-harmonic generation (SHG) in photonic bandgap material doped with a nonlinear χ((2)) effect and the NLH equation modeling wave propagation in Kerr type gratings with a nonlinear χ((3)) effect in the one-dimensional case. Both of these nonlinear phenomena arise as a result of the combination of high electromagnetic mode density and nonlinear reaction from the medium. When the mode intensity of the incident wave is significantly strong, which makes the nonlinear effect non-negligible, numerical methods based on the linearization of the essentially nonlinear problem will become inadequate. In this work, a robust, stable numerical scheme is designed to simulate the NLH equations with strong nonlinearity.

Blue light generation in a ridge waveguide MgO:LiNbO3 crystal pumped by a fiber Bragg grating stabilized laser diode

We report cw blue light generation by using a periodically poled MgO:LiNbO(3) crystal with a ridge waveguide pumped by a fiber Bragg grating stabilized laser diode with 0.25 nm spectrum width in the coherent collapse regime. Blue light generation of 73 mW with 27% conversion efficiency and a wide temperature tolerance of 5.7 degrees C were attained.

Efficient ultraviolet-light (345-nm) generation in a bulk LiIO(3) crystal by frequency doubling of a self-seeded gain-switched AlGaInP Fabry Perot semiconductor laser

A self-seeded gain-switched semiconductor laser is applied as a fundamental optical source to second-harmonic generation, and improvement of frequency-conversion efficiency is demonstrated. 345-nm ultraviolet light of 0.12-muW average power is generated in a bulk LiIO(3) crystal for 690-nm fundamental light of 10.5-mW average power, which is composed of 500-MHz pulse trains emitted from an AlGaInP diode laser with a 68-ps temporal width and a 0.11-nm spectral bandwidth. It is clearly shown that the narrowing of the spectral bandwidth by the self-seeding technique gives rise to a normalized conversion efficiency of 0.218%/Wcm , which is fourtimes larger than that for pulses without seeding.

Highly efficient green-light generation by quasi-phase-matched frequency doubling of picosecond pulses from an amplified mode-locked Nd:YLF laser

We report on first-order quasi-phase-matched frequency doubling of picosecond pulses to the green, using a sample of periodically poled lithium niobate. In cw mode-locked operation, 330 mW of average green power was generated with an average conversion efficiency of ~52%. With a quasi-cw mode-locked pulse train an average conversion efficiency of ~65% was achieved, and 1.3 W of green power (average power within the 10-micros pulse envelope) was produced. At these powers there was no significant photorefractive damage, as confirmed by measured M(2) beam-quality factors of ~1.1 for both output fundamental and second-harmonic beams.

Generation of 340-nm light by frequency doubling of a laser diode in bulk periodically poled LiTaO(3)

Frequency doubling of a 680-nm laser diode in periodically poled LiTaO(3) is presented. By selective proton exchange followed by high-voltage pulse application, a second-order periodic domain inversion having uniform periodicity and optimum duty cycle was fabricated over a 10-mm interaction length in a 200-microm-thick LiTaO(3) substrate. A 340-nm wavelength of harmonic ultraviolet light was generated in a single pass through the domain-inverted structure.