Fabrication and characterization of Ge-Ga-Sb-S glass microsphere lasers operating at ～1.9μm

摘要

We report the fabrication and characterization of germanium gallium antimony sulfide (Ge-Ga-Sb-S or 2S2G,doped with Tm3+ ions) microsphere lasers operating at ～l.9-μm spectral band.Compared to the chalcogenide glasses that are used in previous microsphere lasers,this 2S2G glass has a lower transition temperature and a higher characteristic temperature.This implies that 2S2G microspheres can be fabricated at lower temperatures and the crystallization problem in the sphere-forming process can be alleviated.We show that hundreds of high-quality microspheres (quality factors higher than 105) of various diameters can be produced simultaneously via a droplet sphere-forming method.Microspheres are coupled with silica fiber tapers for optical characterizations.We demonstrate that Whispering Gallery mode (WGM) patterns in the 1.7-2.0 μm band can be conveniently obtained and that once the pump power exceeds a threshold,single-and multi-mode microsphere lasers can be generated.For a typical microsphere whose diameter is 258.64 μm,we demonstrate its laser threshold is 0.383 mW,the laser wavelength is 1907.38 nm,and the thermal sensitivity of the microsphere laser is 29.56 pm/℃.