Dynamic nonlinear thermal optical effects in coupled ring resonators

Chenguang Huang,Lin Zhu,Jiahua Fan

doi:10.1063/1.4743962

Abstract

We investigate the dynamic nonlinear thermal optical effects in a photonic system of two coupled ring resonators. A bus waveguide is used to couple light in and out of one of the coupled resonators. Based on the coupling from the bus to the resonator, the coupling between the resonators and the intrinsic loss of each individual resonator, the system transmission spectrum can be classified by three different categories: coupled-resonator-induced absorption, coupled-resonator-induced transparency and over coupled resonance splitting. Dynamic thermal optical effects due to linear absorption have been analyzed for each category as a function of the input power. The heat power in each resonator determines the thermal dynamics in this coupled resonator system. Multiple “shark fins” and power competition between resonators can be foreseen. Also, the nonlinear absorption induced thermal effects have been discussed.

Highlights

As optical microcavities offer low optical losses together with small mode volume and negligible pump power, they possess an advantage of studying a diverse set of optical phenomena.[1,2,3] This includes generation of nonclassical states, quantum information research,[4] Raman scattering,[5] lasing,[6] parametric oscillation,[7] cavity quantum electrodynamics,[8] biosensing[9] and some other optical effects.[10]
We investigate dynamic thermal nonlinear effects in coupled ring resonators at different input power levels and show that the temperature induced resonance shift of each individual resonator leads to the dynamic power redistribution and corresponding transmission spectrum change
We focus on the linear absorption induced thermal effects in three different characteristic configurations: coupledresonator-induced absorption (CRIA), coupled-resonator-induced transparency (CRIT), and over coupled resonance splitting and analyze the impact of nonlinear thermal effects on the system transmission

Summary

INTRODUCTION

As optical microcavities offer low optical losses together with small mode volume and negligible pump power, they possess an advantage of studying a diverse set of optical phenomena.[1,2,3] This includes generation of nonclassical states, quantum information research,[4] Raman scattering,[5] lasing,[6] parametric oscillation,[7] cavity quantum electrodynamics,[8] biosensing[9] and some other optical effects.[10]. Thermal nonlinear phenomenon has been observed and analyzed in two coupled silica microtoroids[19] and two coupled silica disks.[20] Yet, systematic analysis of the thermal nonlinearity for two coupled microresonators has not been reported. Under-coupling (over-coupling) of the outer resonator will lead to induced absorption (transparency) in the transmission spectrum. Over coupled resonance splitting happens when the two resonators are strongly coupled, which can be considered as a special type of induced transparency. We will show how thermal nonlinear effects induced by linear absorption dynamically change the transmission spectra for these three different configurations. A theoretical model is presented to investigate thermally induced nonlinearity. Simulation results considering the radiation and linear absorption loss are shown for each category with detailed analysis. The impact of nonlinear absorption loss is discussed

THEORY AND MODEL

SIMULATION RESULTS AND ANALYSIS

Over coupled resonance splitting

NONLINEAR ABSORPTION DISCUSSION

CONCLUSION