A fiber-coupled erbium-doped microsphere laser

Summary form only given. Optical microsphere cavities, with their very high quality-factor and sub-millimeter dimensions, are attractive new building block for fiber optics and photonics. A microsphere made of laser-active material, with an efficient optical pumping scheme, can be configured as a miniature solid-state laser. Because of the small volume and high Q of whispering-gallery modes, microsphere lasers can combine very low threshold and narrow emission linewidth. Early reports demonstrated the stimulated emission in dye-doped polysterene spheres with relatively low-Q of /spl sim/10/sup 4/ and free-beam pumping/outcoupling. Reports of high-Q microspheres acting as laser cavities were focused on the achievement of extremely low threshold for laser operation with Nd ions. The 1.56 nm lasing in Er-doped ZBLAN spheres have been reported with pumping and outcoupling by means of bulky prism couplers. We present a miniature design that utilizes a novel angle-polished single-mode fiber coupler for both delivering pump power into the sphere and the pickup of laser radiation.