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

We report parametric gain by utilizing <inline-formula><tex-math notation="LaTeX">$ \chi ^{(2)}$</tex-math></inline-formula> non-linearities in a semiconductor Bragg Reflection Waveguide (BRW) waveguide chip. Under the two-mode degenerate type II phase matching, it can be shown that more than 18 dBs of parametric gain for both TE and TM modes is tenable in 100 s of micrometers of device length. Polarization insensitive parametric gain can be attained within the 1550 nm region of the spectrum. These AlGaAs BRW waveguides exhibit sub-photon per pulse sensitivity. This is in sharp contrast to other types of parametric gain devices which utilize <inline-formula><tex-math notation="LaTeX">$ \chi ^{(3)}$</tex-math></inline-formula>, 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.