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/AIP multilay ers an GaP(111)A substrates based on quasi-phase matching (QPM) for the fun damental standing wave. Theoretical calculation predicted that the SWG powe r increases with increasing number of GaP/AIP 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 tra nsmission SHG measurement using a frequency-tunable Ti:Sapphire laser as a fundamental wave source, maximum SWG power was obtained at a fundamental wa velength of 990 nm from the five-pair GaP/AIP QPM multilayers. The waveleng th conversion efficiency was measured to be 9.8 x 10(-10)%/W, which was sma ller than the theoretical value of 6.5 x 10(-8)%/W.