Quasi-phase-matching (QPM) based on periodic modulation of the nonlinear polarization is a attractive method to obtain highly efficient second-harmonic-generation (SHG), as the large nonlinear coefficient d33 can be used. Utilizing this method, blue light generation has recently been realized in KTP (KTiOPO4)1 and LiNbO32 waveguide. For KTP, blue light of 2mW has been obtained, but the nonlinear coefficient of this material is three times lower than that of LiNbO3. For LiNbO3, as optical damage is known to occur in this material3, its potential for milli-watt order power may be limited.
© 1991 Optical Society of AmericaPDF Article