Combining slow-light and carrier induced nonlinearities in photonic crystal nanocavities

Abstract

Summary form only given. We implement coherent population oscillation and carrier-induced nonlinear refractive index in a semiconductor active nanocavity to strongly increase the photonic lifetime and manipulate its optical response.The so-called photonic crystal L3 cavity, given by three missing holes in a 2D photonic crystal (2D-PhC), is an emblematic illustration of a nanocavity with strong light confinement due to high-Q resonance and small mode volume [1]. Strong electronic confinement can also be achieved provided the cavity contains active semiconductor nanostructures such as quantum wells (QWs) or dots. These two effects lead to the enhancement of the light-matter interaction and, potentially, to a modification of photonic, electronic and thermal characteristic times. Thus, semiconductor 2D-PhC L3 nanocavities are excellent candidates for the implementation of advanced nonlinear photonic interactions. In this work we study the combined effects of both coherent population oscillation (CPO) and carrier-induced nonlinear dephasing in the photon lifetime of a L3 cavity incorporating 4 InGaAsP/InGaAs QWs. The CPO induces a decrease of the group velocity through a strong dispersion of the refractive index (i.e. slow light effect) while the nonlinear phase shift, if implemented close to the bistability threshold, ends up with a strong slowing down of the optical response. The resulting cavity lifetime strongly depends on the control parameters. It is then possible to actively control the photon lifetime of the nanocavity, to enhance its quality factor, to achieve differential amplification under the slow-light regime and to benefit from frequency pulling During this presentation we will discuss theoretically [1] all these aspects with respect to the role of CPO and dynamical nonlinear responses. We will further present recent experimental results [2] demonstrating the enhancement by two orders of magnitude of the cavity lifetime together with the frequency pulling effect.Γ