Vertical microcavities based on photonic crystal mirrors for III-V/Si integrated microlasers Lydie Ferrier*, Salim Boutami, Fabien Mandorlo, Xavier Letartre, Pedro Rojo Romeo, Pierre Viktorovitch, Université de Lyon, Institut des Nanotechnologies de Lyon, INL, UMR CNRS 5270, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, Ecully, F-69134; Philippe Gilet, Badhise Ben Bakir, Philippe Grosse, Jean-Marc Fedeli et Alexei Chelnokov CEA-Léti, MINATEC, 17 Rue des Martyrs, 38054 Grenoble cedex 9 - France ABSTRACT The on-coming photonic layer of CMOS integrated circuits needs efficient light sources to treat and transmit the flow of data. We develop new configurations of III-V/Si vertical cavity lasers coupled to silicon optical waveguides using mirror/coupler based on photonic crystals. These devices can be fabricated using fully CMOS-compatible technological steps. Using this approach, the optical gain is provided by the III-V material, while all the remaining part of the optical cavity is in silicon. The output coupling to the sub-µm waveguides of the CMOS optical layer can then be inherently optimised since the laser mirror/coupler and the Si output waveguides will be realised together during the same fabrication step. It has been demonstrated that photonic crystals membrane can act as very efficient reflectors (PCM-mirrors) for vertical microresonators [1]. In this communication, the design of a vertical cavity microlaser based on these PCM-mirrors will be presented. We will show that high Q-factors (>10000) along with strong vertical and lateral confinements can be achieved. As a first demonstration, experimental results on silicon PhC-mirrors and associated vertical cavities will be discussed, showing Q factors larger than 2000. Finally, theoretical results on the coupling between such cavities and a silicon micro-waveguide will be presented. Keywords: Vertical cavity lasers, nanophotonic devices, photonic crystal slabs, *Lydie.Ferrier@ec-lyon.fr 1. INTRODUCTION Very efficient reflectors based on high index contrast photonic crystal (PhC) slabs exploiting slow Bloch modes above the light cone combine several advantages: the use of a single patterned layer contrary to multilayer Bragg mirrors make them very attractive for ultra-compact photonic devices. Besides, by using a 1D PhC slab, one can control the polarization of the reflected light. In addition, the design of 1D photonic crystal slab reflectors can lead to reflection over a wide wavelength range, usually several hundreds of nanometers. Vertical microcavity based on two PhC reflectors will be thus the most compact Fabry-Pérot cavity ever realized which enable also a polarization control. The integration of such devices into Photonic Integrated Circuits can be reachable by coupling the microcavities to sub-µm refractive waveguides. Recently, 2D PhC mirrors patterned in high index contrast membranes has been realized [1]. Based on these first promoting attempts, we will first show calculation and experimental results for mirrors constituted by 1D silicon PhC embedded in silica. High reflection efficiency can be experimentally obtained from such structures that can be thus considered for the realization of ultra small vertical microcavities. Very compact vertical cavities based on two PhC reflectors have been recently proposed [2]. By adjusting the gap between the two PhC, quality factor higher than 20000 can be obtained with a device having a lateral size of 20µm. These kinds of devices differ from classical microcavities formed by two Bragg mirror by their obvious compactness and efficiency. In a recent paper [3], the substitution of the upper Bragg mirror by a high index contrast grating constitutes the first step to the miniaturization of conventional microcavities. Following the concept proposed in [2], which is to use Photonic Crystal Materials and Devices VIII, edited by Richard M. De La Rue, Ceferino López, Michele Midrio, Pierre Viktorovitch, Proc. of SPIE Vol. 6989, 69890W, (2008) 0277-786X/08/$18 · doi: 10.1117/12.781328 Proc. of SPIE Vol. 6989 69890W-1