A χ²-based AlGaAs Phase Sensitive Amplifier with Record Gain, Noise and Sensitivity
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Abstract
Phase sensitive amplifiers (PSAs) have the potential to empower substantial advances in emerging generations of optical communication systems as well as classical and quantum on-chip signal processing. While the second order nonlinearity (χ2) is stronger than the third order nonlinearity (χ3), it seldom utilized in semiconductors to realise PSAs owing to the challenges of effectively phase matching the interacting waves as well as countering the two-photon absorption of the pump. In this work, we demonstrate the successful design, fabrication, and characterization of the first χ2-based semiconductor PSA using an efficient phase matching approach and a pulsed pump, in an AlGaAs Bragg reflection waveguides. The reported AlGaAs PSA achieves on chip in-phase gain approaching 30 dB, with a sensitivity of 0.005 photons per pulse. Its performance also approaches the theoretical minimal noise figure (NF) of 0 dB. With such performance metrics and its capability to operate in single mode regime, this PSA could usher in a new era of on-chip quantum circuits.