χ²-based AlGaAs phase sensitive amplifier with record gain, noise, and sensitivity

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 second order nonlinearity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>χ</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> ) is stronger than third order nonlinearity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>χ</mml:mi> <mml:mn>3</mml:mn> </mml:msup> </mml:mrow> </mml:math> ), it is seldom utilized in semiconductors to realize 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, to our knowledge, the first <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>χ</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> -based semiconductor PSA using an efficient phase matching approach and a pulsed pump, in an AlGaAs Bragg reflection waveguide. 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 of 0 dB. With such performance metrics and its capability to operate in the single mode regime, this PSA could usher in a new era of on-chip quantum circuits.