An Optical Parametric Amplifier via $ \chi^{(2)} $ in AlGaAs Waveguides

We report parametric gain by utilizing $\chi^{(2)}$ non-linearities in a semiconductor Bragg Reflection Waveguide (BRW) waveguide chip. Under the two-mode degenerate type II phase matching, it can be shown that more than 18 dBs of parametric gain for both TE and TM modes is tenable in 100s of micrometers of device length. Polarization insensitive parametric gain can be attained within the 1550 nm region of the spectrum. These AlGaAs BRW waveguides exhibit sub-photon per pulse sensitivity. This is in sharp contrast to other types of parametric gain devices which utilize $\chi^{(3)}$, where the pump wavelength is in the vicinity of the signal wavelength. This sensitivity, which reached 0.1~photon/pulse, can usher a new era for on-chip quantum information processing using compact, micrometer-scale devices.