Tunable Modulational Instability Sidebands via Parametric Resonance in Periodically Tapered Optical Fibers

TL;DR

This paper investigates modulation instability in periodically tapered optical fibers, deriving analytical estimates and designing fibers to generate widely tunable, narrow instability sidebands for quantum optics applications.

Contribution

It provides accurate analytical estimates of resonance parameters and designs a tapered fiber to produce highly tunable, narrow instability sidebands.

Findings

Analytical estimates of resonant detuning and gain are improved.

Designed fiber achieves narrow sidebands at 35 THz detuning.

Wide tunability of instability peaks enables applications in quantum optics.

Abstract

We analyze the modulation instability induced by periodic variations of group velocity dispersion and nonlinearity in optical fibers, which may be interpreted as an analogue of the well-known parametric resonance in mechanics. We derive accurate analytical estimates of resonant detuning, maximum gain and instability margins, significantly improving on previous literature on the subject. We also design a periodically tapered photonic crystal fiber, in order to achieve narrow instability sidebands at a detuning of 35 THz, above the Raman maximum gain peak of fused silica. The wide tunability of the resonant peaks by variations of the tapering period and depth will allow to implement sources of correlated photon pairs which are far-detuned from the input pump wavelength, with important applications in quantum optics.