An Exciton-Polariton Fano Resonance Driven by Second Harmonic Generation

TL;DR

This paper demonstrates how angle-resolved second harmonic generation spectra of ZnO microwires reveal tunable Fano resonances near exciton-polariton modes, providing insights into the system's quantum dynamics through phase-controlled interference.

Contribution

It introduces a phase-tuning method to control Fano resonance line shapes in SHG spectra of exciton-polariton systems, supported by a theoretical model matching experimental data.

Findings

Fano resonances observed in SHG spectra near exciton-polariton modes

Fano asymmetry parameter q can be tuned by phase-shift between channels

Phase-to-q relation reveals system dynamics and quantum state superpositions

Abstract

Angle-resolved second harmonic generation (SHG) spectra of ZnO microwires show characteristic Fano resonances in the spectral vicinity of exciton-polariton modes. The output SHG spectra after SHG interacting with exciton polariton shows a resonant enhancement peak accompanied by a suppression dip originating from the constructive and destructive interference respectively. It is demonstrated that the Fano line shape, and thus the Fano asymmetry parameter q, can be tuned by the phase-shift of the two channels. The phase-dependent q was calculated and the model describes our experimental results well. In particular, the phase-to-q relation unveil the crucial information about the dynamics of the system, e.g., defining the line shape of output SHG spectra in a superposition of quantum states.