Observation of nonlinear thermal optical dynamics in a chalcogenide nanobeam cavity

TL;DR

This paper investigates the nonlinear thermo-optic effects in chalcogenide glass nanobeam cavities through combined theoretical and experimental methods, revealing unique spectral and dynamic behaviors influenced by parasitic cavity coupling.

Contribution

It provides the first detailed analysis of nonlinear thermal optical dynamics in suspended chalcogenide nanobeam cavities, highlighting the role of parasitic Fabry-Perot cavities in thermal state discontinuities.

Findings

Identification of periodic fringes in spectral response

Observation of a critical wavelength jump

Detection of saturated time delay at high modulation frequencies

Abstract

We present a theoretical and experimental analysis of nonlinear thermo-optic effects in suspended chalcogenide glass nanobeam cavities. We measure the power dependent resonance peaks and characterise the dynamic nonlinear thermo-optic response of the cavity under modulated light input. Several distinct nonlinear characteristics are identified, including a modified spectral response containing periodic fringes, a critical wavelength jump and saturated time delay for modulation frequency faster than the thermal characteristic time. We reveal that the coupling to a parasitic Fabry-Perot cavity enables isolated thermal equilibrium states resulting in the discontinuous thermo-optic critical point.