Broadband second harmonic generation with simultaneous group-velocity matching and quasi-phase matching

Broadband and efficient second harmonic generation in periodically poled potassium niobate (PPKN) for ultra-fast pulse doubling have been theoretically investigated. Simultaneous group-velocity matching (GVM) and quasi-phase matching (QPM) have been achieved between the fundamental and the second harmonic waves by utilizing d(31) and d(32) components of nonlinear coefficient. Second harmonic bandwidths of 46 and 30 nm were calculated at the fundamental wavelengths 1505 and 1314 nm, respectively, with 10-mm interaction length. Proposed broadband interaction scheme can be useful for about 100-fs pulse doubling without temporal pulse broadening in the S and O-bands of telecommunication range.