Studying the microcavity lasers as active dielectric resonator antennas

Micron-scale semiconductor, crystalline and polymer lasers exploit emission of light from the cavities made of active dielectric materials, which are able to display inversed population under pumping and thus provide optical gain. They are intensively studied both experimentally and theoretically, as coherent sources of the visible, infrared and terahertz waves. Here, well developed etching and epitaxial technologies enable fabrication of thin planar cavities with controlled contour shape. Thus, the laser resonators either stand on small pedestals in free space or lay on a substrate, with in-plane dimensions comparable to and thickness much smaller than the optical wavelength. From the one hand, if one considers a laser as a source then its main characteristics are the frequencies of emission and the associated thresholds of pumping or, equivalently, of material gain. From the other hand, as the intrinsic property of laser is the radiation so it can be also viewed as an antenna. Then, the sought far-field characteristics are the angular pattern of emission and the directivity. In this paper, we study the lasing frequencies, thresholds and far-field patterns for a kite cavity using specifically tailored electromagnetic eigenvalue problem.