Theory of cavity-enhanced spontaneous parametric downconversion

TL;DR

This paper provides a theoretical analysis of photon pair generation in nonlinear cavities via spontaneous parametric downconversion, focusing on spectral properties and source brightness enhancement in different resonant regimes.

Contribution

It introduces analytic models for joint spectral amplitude in singly- and doubly-resonant cavities, highlighting bandwidth reduction and brightness enhancement effects.

Findings

Bandwidth decreases with higher cavity finesse

Source brightness is significantly enhanced by the cavity

Analytic expressions for joint spectral amplitude are derived

Abstract

In this paper we study photon pairs generated in a nonlinear cavity, composed of a nonlinear crystal surrounded by mirrors, by the process of spontaneous parametric downconversion. We analyze two different regimes: singly-resonant cavities where the signal and idler modes are resonant, and doubly-resonant cavities where the pump mode is also resonant. We present analytic expressions for the joint spectral amplitude in these two cases, and study the reduction in emission bandwidth as the cavity coefficient finesse is increased. We also study the enhancement of the source brightness resulting from the presence of the cavity.