Near-field and far-field analysis of an azimuthally polarized slow Bloch mode microlaser

We report on the near-and far-field investigation of the slow Bloch modes associated with the G point of the Brillouin zone, for a honeycomb lattice photonic crystal, using near-field scanning optical microscopy (NSOM) and infra-red CCD camera. The array of doughnut-shaped monopolar mode (mode M) inside each unit cell, predicted previously by numerical simulation, is experimentally observed in the near-field by means of a metal-coated NSOM tip. In far-field, we detect the azimuthal polarization of the doughnut laser beam due to destructive and constructive interference of the mode radiating from the surface (mode TEM01*). A divergence of 2 degrees for the laser beam and a mode size of (12.8 +/- 1) mu m for the slow Bloch mode at the surface of the crystal are also estimated. (C) 2010 Optical Society of America