Patricio Grinberg

Coupling light into a slow-light photonic-crystal waveguide from a free-space normally-incident beam

We present a coupler design allowing normally-incident light coupling from free-space into a monomode photonic crystal waveguide operating in the slow-light regime. Numerical three-dimensional calculations show that extraction efficiencies as high as 80% can be achieved for very large group indices up to 100. We demonstrate experimentally the device feasibility by coupling and extracting light from a photonic crystal waveguide over a large group-index range (from 10 to 60). The measurements are in good agreement with theoretical predictions. We also study numerically the impact of various geometrical parameters on the coupler performances.

Enhancement of a nano cavity lifetime by induced slow light and nonlinear dispersions

We start from a 2D photonic crystal nanocavity with moderate Q-factor and dynamically increase it by two order of magnitude by the joint action of coherent population oscillations and nonlinear refractive index.

Exciton spin coherence in InGaAs/GaAs quantum dots revisited by heterodyne pump-probe experiment (Withdrawal Notice)

Publisher’s Note, 1 December 2016: This paper, originally published on 11/9/2016, was withdrawn at request of the authors.

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

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

Photonic crystal nanocavity lifetime enhancement by slow light propagation and carrier induced nonlinearities

Coherent population oscillations and carrier-induced nonlinear refractive index dispersion are implemented in an active semi-conductor photonic crystal nanocavity to increase its photonic lifetime and manipulate its optical response.

Cavity lifetime control by slow-light and nonlinear effects

We show both theoretically and experimentally that the lifetime of an active semiconductor photonic crystal nanocavity is enhanced thanks to the combination of two cooperative effects: slow light propagation based on coherent-population-oscillation effect and optical bistability. In particular we develop an analytical analysis enabling us to clearly show the physical mechanisms producing the enhancement of the cavity lifetime.

Enhanced nanocavity Q-factor via slow light propagation and nonlinear effects

We show that the quality factor Q of a nanocavity is enhanced when containing a dispersive slow-light medium. The strong dispersion is achieved using the Coherent Population Oscillation (CPO) effect in the quantum wells of a 2-dimensionnal photonic crystal nanocavity. Starting with a nanocavity having a Q-factor of 6300, we end up with a Q-factor of 410000. This demonstration has further been confirmed by measuring a cavity lifetime of 342 ps, whereas the initial cavity lifetime of about 5.2 ps.

Enhancement of a nanocavity lifetime using slow light propagation

We demonstrate that the lifetime of a nanocavity can be enhanced by inserting a medium with a strong index dispersion in the cavity. The strong dispersion is achieved through coherent population oscillations effect in the quantum wells of a two-dimensional photonic crystal nanocavity. The initial cavity lifetime of ~3-6ps has been extended to a maximum value of about 336 ps.

Coherent and Dynamic Nonlinear Interactions in 2D Photonic Crystal nanocavities

By coupling light resonantly into a nanocavity new avenues are open to efficiently produce nonlinear coherent interactions. We discuss recent results on optical bistability, excitability and slow light in semiconductor L3 Photonic Crystal nanocavities.

Enhancement of a nanocavity lifetime through slow light propagation

We predict that the lifetime of a semiconductor two-dimensional photonic crystal nanocavity can be enhanced by inserting a medium with a large group index associated to a strong index dispersion. We particularly consider the case of coherent population oscillations effect in a semiconductor nanocavity containing quantum wells as active medium.