Stéphane Calvez

Robust and simplified cat's-eye external-cavity lasers using cavity resonant integrated grating filters

We present a simple frequency-selective 3-element cats-eye cavity laser enabled by a new optical element, the so-called Cavity Resonant Integrated Grating Filter (CRIGF). Output powers in excess of 30 mW are achieved with single-mode emission. Discrete tuning around a central wavelength of 850 nm is achieved over a 30 nm band using a semiconductor source with an AR coated output facet. We will discuss the performance of the laser source together with new requirements for the CRIGFs. The road to enhanced performance will be outlined.

Vertical integration of an electro-absorption modulator within a VCSEL device

The huge increase of datacom traffic requires laser sources of ever-widening modulation bandwidth. Vertical-Cavity Surface-Emitting Lasers (VCSEL) are strategically relevant given that their wide use for short communication links such as in datacenters and are, in light of recent developments, good candidates to address such demands. We propose to increase the modulation bandwidth by vertically integrating a continuous-wave VCSEL with a high-speed electroabsorption modulator (EAM-VCSEL). We will present our studies on the electrical and optical designs, on the development of optimized fabrication steps and on the microwave characterizations leading to the realization of integrated EAM-VCSEL devices.

Anisotropic oxidation of circular mesas for complex confinement in photonic devices: Experiments and modelling

In many different AlGaAs-based photonic and optical devices, the selective oxidation of an Al-rich layer is a very efficient way to create a lateral electrical and optical confinement. The degree of lateral confinement can thus be adjusted with the depth of the oxide within the structure. It is then of primary importance to control the lateral spreading of the oxidation reaction and that in all the crystallographic directions in order to master the waveguide properties in the 3 directions. Thanks to the epitaxial structure the vertical confinement can be designed with the index profile of the epitaxial multilayers, but in the lateral directions (in the plane of the epilayers) only the kinetics of the selective oxidation steers the waveguide dimensions.

Coupled mode analysis of micro-disk resonators with an asymmetric- index-profile coupling region

In this article, we apply the coupled-mode theory to vertically-coupled micro-disk resonators presenting an asymmetric distribution of refractive index and a multilayer separation region between the two waveguide cores, resulting in an effective propagation constant phase-mismatch in the coupling region. We introduce a criterion which, given the coupler overall permittivity distribution, clarifies how to best choose the individual decomposition index profiles among the various possible solutions. Following our recent experimental demonstration we subsequently exploit the derived decomposition to evaluate the theoretical transmission characteristics of an AlGaAs/AlOx-based structure as function of wavelength and as function of the position of the resonator relative to the access waveguide.We show that the resonant dips of the intensity transmission, spaced by the cavity FSR, are modulated by an envelop which governs the coupling regime of the resonator-waveguide system.