Proceedings Article | 31 January 2014
Proc. SPIE. 8993, Quantum Sensing and Nanophotonic Devices XI
KEYWORDS: Semiconductors, Mirrors, Optical parametric oscillators, Waveguides, Signal attenuation, Interfaces, Gallium arsenide, Reflectivity, Heterojunctions, Oxidation
Within the ambitious quest for an electrically pumped version of the optical parametric oscillator (OPO), we demonstrate
the first near-infrared integrated OPO in a direct gap semiconductor. This nonlinear device is based on a selectively
oxidized GaAs/AlAs heterostructure, the same “AlOx” technology that is at the heart of VCSEL fabrication. The
heterostructure and waveguide design allows for type-I form-birefringent phase matching, with a TM<sub>00</sub> pump around 1 μm and TE<sub>00</sub> signal and idler around 2 μm. Relying on the high non-resonant χ<sup>(2)</sup> of GaAs, relatively weak guided-wave optical losses, and monolithic SiO<sub>2</sub>/TiO<sub>2</sub> dichroic Bragg mirrors, we observe a threshold of 210 mW at degeneracy in the continuous-wave regime, with a single-pass-pump doubly resonant scheme. Further improvement can be achieved by adopting a double-pump-pass scheme and, in a more fundamental way, by further optimizing the waveguide optical
losses. The latter are induced by a not entirely mastered AlAs oxidation process and are of two distinct types: Rayleighlike
scattering at signal and idler wavelength (α ≤ 1cm<sup>-1</sup>), due to the interface roughness between GaAs and AlOx layers; and absorption at pump wavelengths (α ≈ 3cm<sup>-1</sup>), due to volume defects in the GaAs layers adjacent to the aluminum oxide. This result marks a milestone for integrated nonlinear photonics and represents a significant step toward the goal of a broadly tunable coherent light source on chip.
