Toward an AlGaAs/AlOx near-infrared integrated optical parametric oscillator
Résumé
We report on the observation of self-amplified parametric downconversion in a selectively oxidized AlGaAs cavity that was designed to perform as a guided-wave optical parametric oscillator in the near infrared. To date, two technological factors preclude such oscillation and are thoroughly investigated here: oxidation-induced optical propagation losses and the reflectivity of the waveguide resonator facets. The spectral study of the former has singled out two distinct mechanisms: scattering at the oxide interfaces and absorption by point defects in the oxide neighboring layers. Regarding the latter, dielectric mirrors have been designed and deposited on the ridge waveguide facets, with modal reflectivities of ∼10% at pump wavelength and ∼90% at signal/idler wavelengths. With respect to the case of a mirrorless waveguide, the monolithic cavity enabled a factor-2 enhancement of the conversion efficiency, indicating the close proximity of the oscillation threshold.