Measurement of Squeezed Vacuum Based on Si₃N₄ Photonic Ring Molecules

We report our work on the development of an on-chip squeezer for the generation of single-mode squeezed vacuum (SQV) light. The integrated squeezer is resonator-based, made up of two coupled Si<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> micro-ring resonators (MRR). Such structure, often coined as photonic ring molecules, is designed to suppress the unwanted nonlinear processes which can cause excess noises to contaminate the single-mode squeezed light generated via degenerate four-wave mixing (DG-FWM). Through such an integrated Si<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> squeezer, we generated SQV light showing a directly measured squeezing (anti-squeezing) level of −0.67 dB (2 dB), corresponding to an on-chip squeezing (anti-squeezing) level of −3.36 dB (5 dB).