Tunable High-Q Directional Random Laser from a Planar Random Microcavity

Summary form only given. In the new developed microcavity structure, photons inside the hybrid cavity are trapped 3-dimensionally. Therefore, optical modes of the cavity were significantly reduced. Consequently, the laser threshold, divergence angle of emitted laser beam, and the spectral linewidth of the laser emission was substantially reduced by two-fold confinement effects from transverse random cavities and vertical planar microcavity. In this paper, we demonstrated a wavelength tunable planar random microcavity laser. We used dye doped liquid crystal as the gain layer so that the defect mode position can be easily tuned by changing temperature. We reported a nearly single mode ultra-narrow linewidth laser emission from the optically pumped hybrid cavity structure. The 0.03 nm linewidth (corresponding to Q>20000) is about two orders of magnitude narrower than that from a conventional planar microcavity. Tunable random laser emission was observed when the environment temperature was slightly increased.