Effect of group-velocity dispersion on the generation of multimode pulsed squeezed light in a synchronously pumped optical parametric oscillator

TL;DR

This paper investigates how group-velocity dispersion impacts the generation and properties of multimode pulsed squeezed light in a synchronously pumped optical parametric oscillator, revealing mode-dependent detuning, coupling effects, and implications for quantum state quality.

Contribution

It introduces a detailed timedomain model considering intracavity dispersion, analyzing its effects on supermode squeezing, entanglement, and potential for experimental studies in multimode quantum optics.

Findings

Dispersion causes mode-dependent detuning of supermodes.

Dispersion influences squeezing levels and squeezing ellipse rotation.

Reduced shot noise suppression due to dispersion effects.

Abstract

Parametric down-conversion in a nonlinear crystal is a widely employed technique for generating quadrature squeezed light with multiple modes, which finds applications in quantum metrology, quantum information and communication. Here we study the generation of temporally multimode pulsed squeezed light in a synchronously pumped optical parametric oscillator (SPOPO) operating below the oscillation threshold, while considering the presence of non-compensated intracavity group-velocity dispersion. Based on the developed timedomain model of the system, we show that the dispersion results in mode-dependent detuning of the broadband supermodes of the pulsed parametric process from the cavity resonance, as well as linear coupling between these supermodes. With the perturbation theory up to the second order in the coupling coefficients between modes, we obtained a solution for the supermode amplitudes given an arbitrary number of modes and pump level. The dispersion affects the quantum state of the supermodes by influencing their squeezing level and the rotation of the squeezing ellipse. It also affects the entanglement among the supermodes, leading to reduced suppression of shot noise level as measured in the balanced homodyne detection scheme. Furthermore, our study highlights the potential of SPOPO with group-velocity dispersion as a testbench for experimental investigations of multimode effects in linearly evanescent coupled parametric oscillators.