Quasi-phase-matched second-harmonic generation using a planar waveguide with an X-axis inverted periodical structure of 2-methyl-4-nitroaniline (MNA) crystals

We have realized quasi-phase-matched second-harmonic generation by using a planar waveguide consisting of periodical ridge-shaped crystals of 2-methyl-4-nitroaniline (MNA). The largest nonlinear optical coefficient d11 of MNA was used. The quasi-phase matching was attained by angle tuning to coherence lengths corresponding to conversions from fundamental TE0 and TE2 modes into second-harmonic TE10 and TE12 modes, respectively.