Thin-film lithium niobate (TFLN) has recently emerged as a promising platform for integrated nonlinear photonics, enabling the use of optical parametric amplifiers (OPAs) for applications in quantum information processing, precision metrology, and ultrafast optical signal processing. However, OPA waveguide designs have not yet achieved the phase-matching conditions for type-0 operation in a single spectro-temporal mode, limiting their use. We optimize the waveguide dimensions, poling pattern, pump wavelength, and pump pulse duration for high spectral purity, a metric for single-mode fidelity. We numerically demonstrate a nanophotonic OPA with a spectral purity of 0.982 in a TFLN waveguide. Through semi-classical simulations, we further demonstrate that in the optical parametric regime, where vacuum fluctuations at the input of the OPA can saturate the gain and deplete the pump, the macroscopic output of such a single-mode OPA can be utilized for an ultra-fast quantum random number generator. These results demonstrate a promising direction for integrated OPAs in a wide range of ultrafast quantum nanophotonics applications.
Quantum noise limits the sensitivity of optical measurements, but squeezed states of light enable quantum-enhanced metrology, sensing, and information processing. Most on-chip squeezed-light sources rely on Kerr (
χ(3)) nonlinearities, remain limited by pump power and excess loss constraints. Quadratic (
χ(2)) platforms instead provide stronger parametric interactions, lower pump power requirements, and greater spectral engineering flexibility. Here, we demonstrate strong, broadband squeezed-light generation on a thin-film lithium niobate (TFLN) photonic chip using a dual-resonant optical parametric amplifier implemented in a single periodically poled LN (PPLN) microresonator. Near-full-depth domain inversion is achieved simultaneously with highly over-coupled resonances, exhibiting escape efficiencies exceeding 90% and intrinsic quality factors above 2.5 million in a 0.6 mm
2 X-cut TF-PPLN resonator, enabling efficient squeezing at 1587 nm when pumped at 793.5 nm. Operating in the continuous-wave regime, we directly measure -0.81 dB of squeezing below the shot-noise limit with a pump power of 27 mW, together with +4.29 dB of anti-squeezing. From these measurements, we infer an on-chip squeezing level of -7.52 dB
± 0.22 dB (95% confidence interval: [-7.96,-7.10] dB), and an on-chip anti-squeezing level of +9.62 dB
± 0.25 dB. We demonstrate single-mode squeezing at degeneracy with a squeezed-light spectrum exceeding 10.3 THz. This work reports the highest squeezing ratio among integrated
χ(2) cavity platforms and the first quasi-phase matched, fully resonant
χ(2) cavity squeezer on chip, establishing a scalable route to fully integrated power-efficient squeezed-light sources for quantum-enhanced sensing and metrology.
Abstract Quantum noise limits the sensitivity of optical measurements, but squeezed states of light enable quantum-enhanced metrology, sensing, and information processing. Most on-chip squeezed-light sources rely on Kerr (χ(3)) nonlinearities, remain limited by pump power and excess loss constraints. Quadratic (χ(2)) platforms instead provide stronger parametric interactions, lower pump power requirements, and greater spectral engineering flexibility. Here, we demonstrate strong, broadband squeezed-light generation on a thin-film lithium niobate (TFLN) photonic chip using a dual-resonant optical parametric amplifier implemented in a single periodically poled LN (PPLN) microresonator. Near-full-depth domain inversion is achieved simultaneously with highly over-coupled resonances, exhibiting escape efficiencies exceeding 90% and intrinsic quality factors above 2.5 million in a 0.6mm2 X-cut TF-PPLN resonator, enabling efficient squeezing at 1587nm when pumped at 793.5 nm. Operating in the continuous-wave regime, we directly measure −0.81 dB of squeezing below the shot-noise limit with a pump power of 27mW, together with +4.29 dB of anti-squeezing. From these measurements, we infer an on-chip squeezing level of −7.52 dB±0.22 dB (95% confidence interval: [−7.96,−7.10] dB), and an on-chip anti-squeezing level of +9.62 dB±0.25 dB . We demonstrate single-mode squeezing at degeneracy with a squeezed-light spectrum exceeding 10.3 THz. This work reports the highest squeezing ratio among integrated χ(2) cavity platforms and the first quasi-phase matched, fully resonant χ(2) cavity squeezer on chip, establishing a scalable route to fully integrated power-efficient squeezed-light sources for quantum-enhanced sensing and metrology.
Squeezed light is a key quantum resource that enables quantum advantages for sensing, networking, and computing applications. The scalable generation and manipulation of squeezed light with integrated platforms are highly desired for the development of quantum technology with continuous variables. In this Letter, we demonstrate squeezed light generation with thin-film lithium niobate integrated photonics. Parametric down-conversion is realized with quasi-phase matching using ferroelectric domain engineering. With sub-wavelength mode confinement, efficient nonlinear processes can be observed with single-pass configuration. We measure 0.56 ± 0.09 dB quadrature squeezing (∼2.6 dB inferred on-chip). The single-pass configuration further enables the generation of squeezed light with large spectral bandwidth up to 7 THz. This work represents a significant step towards the on-chip implementation of continuous-variable quantum information processing.