Noncollinear type Ⅱ second harmonic generation in Al_((0.3))Ga_((0.7))As/Al_2O_3 one-dimensional photonic bandgap structure

摘要

We have designed a one-dimensional photonic bandgap crystal to obtain perfect phase-matching conditions for noncollinear type Ⅱ quadratic processes. The realized sample was 15 periods of Al_((0.3))Ga_((0.7))As/Al_2O_3, for a total length of 3.5μm. Noncollinear type Ⅱ phase-matching was obtained at 1510nm. We have experimentally verified the band structure characteristic as well as its perfect phase-matching for the noncollinear type Ⅱ parametric process. Indeed, noncollinear type Ⅱ second harmonic generation was obtained for the first time in a PBG crystal. The experiment demonstrated that the breaking of symmetry, which is artificially induced in such a structure, and the field resonance effect give rise to a relatively efficient second harmonic generation even using a naturally isotropic material (AlGaAs). In fact, we report a nonlinear effective coefficient of the sample equal to (52+-12) pm/V.