Multi-mode theory of pulsed twin beams generation using a high gain fiber optical parametric amplifier

TL;DR

This paper presents a theoretical analysis of quantum noise in high gain fiber optical parametric amplifiers, highlighting conditions for optimal noise performance and effects of experimental imperfections.

Contribution

It introduces a multi-mode theoretical framework for pulse pumped FOPAs and examines quantum noise properties considering realistic experimental conditions.

Findings

Noise figure exceeds 3 dB limit unless joint spectral function is factorable

Twin beam intensity difference noise can be below shot-noise limit with proper mode matching

Numerical simulations include experimental imperfections for realistic predictions

Abstract

Using the Bogoliubov transformation in multi-frequency modes to describe the evolution of the non-degenerate signal and idler twin beams, we theoretically investigate the quantum noise properties of the pulse pumped high gain fiber optical parametric amplifiers (FOPA). The results show that the noise figure of the FOPA is generally greater than the 3 dB quantum limit unless the joint spectral function is factorable and the spectrum of the input signal well matches the gain spectrum in the signal band. However, the intensity difference noise of the twin beams, which weakly depends on the joint spectral function, can be significantly less than the shot-noise limit when the temporal modes of the pump and the input signal are properly matched. Moreover, to closely resemble the real experimental condition, the quantum noise of twin beams generated from a broadband FOPA is numerically studied by taking the various kinds of experimental imperfections into account. Our study is not only useful for developing a compact fiber source of twin beams, but also helpful for understanding the quantum noise limit of a pulse pumped FOPA in the fiber communication system.