Phase-matching-free parametric oscillators based on two dimensional semiconductors

TL;DR

This paper introduces a novel phase-matching-free parametric oscillator using monolayer transition-metal dichalcogenides, enabling miniaturized, tunable, and efficient sources for quantum and sensing applications.

Contribution

It demonstrates a new type of miniaturized parametric oscillator that operates without phase-matching constraints by leveraging two-dimensional semiconductors and exact nonlinear Maxwell solutions.

Findings

Achieves phase-matching-free operation in micro-resonators

Enables tunable emission via pump angle adjustment

Allows electrical modulation through doping and gating

Abstract

Optical parametric oscillators are widely-used pulsed and continuous-wave tunable sources for innumerable applications, as in quantum technologies, imaging and biophysics. A key drawback is material dispersion imposing the phase-matching condition that generally entails a complex setup design, thus hindering tunability and miniaturization. Here we show that the burden of phase-matching is surprisingly absent in parametric micro-resonators adopting monolayer transition-metal dichalcogenides as quadratic nonlinear materials. By the exact solution of nonlinear Maxwell equations and first-principle calculation of the semiconductor nonlinear response, we devise a novel kind of phase-matching-free miniaturized parametric oscillator operating at conventional pump intensities. We find that different two-dimensional semiconductors yield degenerate and non-degenerate emission at various spectral regions thanks to doubly-resonant mode excitation, which can be tuned through the incidence angle of the external pump laser. In addition we show that high-frequency electrical modulation can be achieved by doping through electrical gating that efficiently shifts the parametric oscillation threshold. Our results pave the way for new ultra-fast tunable micron-sized sources of entangled photons, a key device underpinning any quantum protocol. Highly-miniaturized optical parametric oscillators may also be employed in lab-on-chip technologies for biophysics, environmental pollution detection and security.