Second-Harmonic Generation from GaP/AlP Multilayers on GaP (111) Substrates Based on Quasi-Phase Matching for the Fundamental Standing Wave

We have demonstrated second-harmonic generation (SHG) from GaP/AlP multilayers on GaP(111)A substrates based on quasi-phase matching (QPM) for the fundamental standing wave. Theoretical calculation predicted that the SHG power increases with increasing number of GaP/AlP multilayers because of their small absorption coefficient in the spectral range of second-harmonic light, which is in contrast to the case of GaAs/AlAs QPM multilayers. In the transmission SHG measurement using a frequency-tunable Ti:Sapphire laser as a fundamental wave source, maximum SHG power was obtained at a fundamental wavelength of 990 nm from the five-pair GaP/AlP QPM multilayers. The wavelength conversion efficiency was measured to be 9.8×10-10%/W, which was smaller than the theoretical value of 6.5×10-8%/W.