Tracking light in high Q low V nanocavities Philippe Velha, Benoit Cluzel, Loic Lalouat, Emmanuel Picard, David Peyrade, Jean Claude Rodier, Thomas Charvolin, Philippe Lalanne, Frédérique de Fornel and Emmanuel Hadji CEA/DRFMC/SiNaPS, 17 rue des martyrs, 38054 Grenoble Cedex 9, France CNRS/IOTA, Université Paris XI, 91403 Orsay Cedex, France CNRS/Université de Bourgogne/LPUB, 9 av. A. Savary, BP 47870, 21078 Dijon, France mailto:emmanuel.hadji@cea.fr Abstract: A near-field optical probe is used to observe the electromagnetic field within photonic crystal nanocavities. The cavity mirrors are designed to provide mode matching. A quality factor enhancement by two orders of magnitude is observed. © 2006 Optical Society of America 1. INTRODUCTION Photonic crystals (PCs) have proven to be an efficient approach to slow down light propagation 1,2 or tightly confine the electromagnetic field 3 . Recent experiments in near field optics 4,5,6,7,8,9 seem to demonstrate the Scanning Near-field Optical Microscopy (SNOM) ability to locally map the electromagnetic field inside integrated photonic devices. In this work we analyze the optical properties of waveguide integrated PC nanocavities by using a SNOM probe in collection mode associated with transmission measurements. We show that strong field confinement enhancement can be achieved by proper mirror designs including mode matching and losses recycling 10 , 11 . These experimental results are discussed in light of numerical calculations. 2. NEAR FIELD SPECTROSCOPY Photonic crystals are designed for the 1.5μm range. The PC is a triangular lattice of air holes etched in a ridge Silicon On Insulator (SOI) waveguide. The samples are characterized at the same time in far-field by coupling an external light source into the waveguide 12 and in near-field by using a SNOM probe above the cavity to visualize the near-field optical distribution at the surface of the sample 13 . The spectra are shown on the figure above. Also shown is the field recorder by the probe above the cavity. We clearly see that two different modes are contributing to the cavity resonance. a98_1.pdf MB5.pdf © 2006 OSA/SL 2006