Temporal Simultons in Optical Parametric Oscillators

TL;DR

This paper demonstrates a new operational regime in optical parametric oscillators where stable, broad bandwidth, few-cycle pulses are generated via the formation of temporal simultons, offering a novel approach to frequency comb production.

Contribution

It introduces the concept of simulton-based operation in OPOs, showing how to achieve stable, efficient, few-cycle pulses using a specific detuning and gain regime.

Findings

Achieved sub-50 fs pulses with high slope efficiency

Demonstrated broad instantaneous bandwidths increasing with pump power

Verified simulton formation through analytical and numerical methods

Abstract

We identify and demonstrate a regime of operation in optical parametric oscillators (OPOs) in which the formation of temporal simultons produces stable half-harmonic pulses. Simultons are simultanous bright-dark solitons of a signal field at frequency $\omega$ and the pump field at $2\omega$ which form in a quadratic nonlinear medium. The formation of simultons in an OPO is evidenced by sech$^2$ spectra with broad instantaneous bandwidths which increase with pump power, and large slope efficiencies. In contrast to conventional synchronously pumped OPOs, operation in this regime is achieved by using relatively large parametric gains, and a low finesse resonator detuned to a slightly longer roundtrip time than the pump repetition period. In the experiment we achieve sub-50 fs sech$^2$ pulses with a slope efficiency of 570%, and a conversion efficiency of 55% as a result of formation of simultons in an OPO. We verify the distinct features of OPO operation in the simulton regime analytically and numerically. These results represent a fundamental shift in the understanding and design of OPOs, in which the nonlinear dynamics that arise during asynchronous operation can be used to efficiently generate few-cycle long-wavelength frequency combs.