Generation of 116-mW output power at 461 nm in a periodically poled lithium niobate waveguide

We demonstrate a second harmonic generation (SHG) of 116 mW at 461 nm in a periodically poled lithium niobate waveguide when the power of the 922-nm fundamental light is coupled into the waveguide was 350 mW. The waveguide is 12.5 μm wide, 12.0 μm thick, 22 mm long, and has a 1-mm-long slab window at the output facet of the waveguide. The temperature acceptance bandwidth of the phase-matching curve of the SHG is approximately 0.5 °C. The SHG system demonstrates good beam quality and is reliable for cold atom experiments, including research on optical lattice clocks.

Nondestructive Measurement for Front Facet Temperature of Semiconductor Lasers

A convenient, simple method is proposed to measure the front facet temperature, which is the highest temperature in the semiconductor laser diode (LD), of a GaAs-based laser by employing thermoreflectance technique. Using an optical system featured in fiber connection, we measured the facet reflectivity of the 808-nm AlGaInAs/AlGaAs LD, which gives information about the temperature of the output facet. The fiber system operates at the wavelength of 1550 nm which avoids the absorption of the probe beam by the tested LD and consists of a fiber-coupled 1550 nm laser illuminant and photodiode. All optical elements in the system are connected by the fibers. The current signal collected from the photodiode is related to the facet reflectivity and represents facet temperature. We compared the facet temperatures determined by thermoreflectance technique with the cavity temperature obtained by forward-voltage method and found that the former is as much as three times as the latter.