Giant phase modulation in a Mach-Zehnder exciton-polariton interferometer

TL;DR

This paper demonstrates a giant phase modulation mechanism in an exciton-polariton Mach-Zehnder interferometer, where small optical injections induce large phase shifts due to strong coupling with slow light modes.

Contribution

It introduces a novel phase modulation method leveraging exciton-polariton interactions in a Mach-Zehnder interferometer, achieving significant phase shifts with minimal control power.

Findings

Achieved at least ten times smaller control power times length for {} phase shift compared to slow light photonic crystal waveguides.

Fabricated a micrometric exciton-polariton Mach-Zehnder interferometer demonstrating the effect.

Observed large phase shifts induced by small optically injected carrier densities.

Abstract

We report on a new mechanism of giant phase modulation. The phenomenon arises when a dispersed photonic mode (slow light) strongly couples to an excitonic resonance. In such a case, even a small amount of optically injected carriers creates a potential barrier for the propagating exciton-polariton which provokes a considerable phase shift. We evidence this effect by fabricating an exciton-polariton Mach-Zehnder interferometer, modulating the output intensity by constructive or destructive interferences controlled by optical pumping of a micrometric size area. The figure of merit for a {\pi} phase shift, defined by the control power times length of the modulated region, is found at least one order of magnitude smaller than slow light photonic crystal waveguides.