Observation of a stronger-than-adiabatic change of light trapped in an ultrafast switched GaAs-AlAs microcavity

TL;DR

This study demonstrates a non-adiabatic, rapid frequency shift of light in a switched GaAs-AlAs microcavity, revealing new dynamics in ultrafast photonic control with potential for advanced optical applications.

Contribution

It provides the first experimental observation of a stronger-than-adiabatic change in trapped light frequency in a microcavity, supported by an analytical model.

Findings

Observed a frequency shift up to 5 linewidths from resonance

Detected a non-adiabatic response of trapped light to ultrafast switching

Developed an analytical model matching experimental dynamics

Abstract

We study the time-resolved reflectivity spectrum of a switched planar GaAs-AlAs microcavity. Between 5 and 40 ps after the switching (pump) pulse we observe a strong excess probe reflectivity and a change of the frequency of light trapped in the cavity up to 5 linewidths away from the cavity resonance. This frequency change does not adiabatically follow the fast-changing cavity resonance. The frequency change is attributed to an accumulated phase change due to the time-dependent refractive index. An analytical model predicts dynamics in qualitative agreement with the experiments, and points to crucial parameters that control future applications.