Cylindrical microcavity laser based on the evanescent-wave-coupled gain

A microcavity laser based on the gain only in the evanescent field region o f whispering gallery modes has been demonstrated. A cylindrical microcavity of 125 mu m diam was surrounded by rhodamine 6G dye molecules in an ethano l solution of lower refractive index such that whispering gallery modes of the microcavity underwent laser oscillation when the dye molecules in the e vanescent field region outside the cavity were excited by a second harmonic of a Nd:YAG laser. For particular pumping spots, single-mode laser oscilla tion of a transverse magnetic mode was observed at about 600 nm with associ ated cavity Q of 3 x 10(7).