Large regenerative parametric amplification on chip at ultra-low pump powers

TL;DR

This paper presents a microresonator-assisted regenerative optical parametric amplifier on chip that achieves high gain with ultra-low pump power, enabling compact, tunable amplification suitable for portable and space-based photonic applications.

Contribution

It introduces a novel regenerative OPA design leveraging microresonators for high gain at low pump power, with engineered gain spectra and demonstrated amplification of Kerr-soliton comb lines.

Findings

30-dB gain with only 9 mW pump power

Engineered gain spectra covering telecom channels

Amplification of Kerr-soliton comb lines while preserving phase

Abstract

Chip-based optical amplifiers can significantly expand the functionalities of photonic devices. In particular, optical-parametric amplifiers (OPAs), with engineerable gain-spectra, are well-suited for nonlinear-photonic applications. Chip-based OPAs typically require long waveguides that occupy a large footprint, and high pump powers that cannot be easily produced with chip-scale lasers. We theoretically and experimentally demonstrate a microresonator-assisted regenerative OPA that benefits from the large nonlinearity enhancement of microresonators and yields a high gain in a small footprint. We achieve 30-dB parametric gain with only 9 mW of cw-pump power and show that the gain spectrum can be engineered to cover telecom channels inaccessible with Er-based amplifiers. We further demonstrate the amplification of Kerr-soliton comb lines and the preservation of their phase properties. Additionally, we demonstrate amplification by injection locking of optical-parametric oscillators, which corresponds to a regenerative amplifier pumped above the oscillation threshold. Novel dispersion engineering techniques such as coupled cavities and higher-order-dispersion phase matching can further extend the tunability and spectral coverage of our amplification schemes. The combination of high gain, small footprint, low pump power, and flexible gain-spectra engineering of our regenerative OPA is ideal for amplifying signals from the nanowatt to microwatt regimes for portable or space-based devices where ultralow electrical power levels are required and can lead to important applications in on-chip optical- and microwave-frequency synthesis and precise timekeeping.