Laser emission from tapered fiber-based liquid-crystal microsphere for sensing

This Letter introduces a novel laser emission probe for liquid-crystal microspheres based on a tapered fiber. A cholesteric liquid crystal (CLC) is injected into a hollow glass microsphere (HGM) attached at the front end of a tapered fiber in order to produce laser. Tapered fibers are preferable to rectangular fibers for liquid-crystal microsphere laser emission. The whispering gallery mode (WGM) laser is significantly suppressed by the tapered fiber-based liquid-crystal microsphere, which also displays an apparent single-mode photonic bandgap (PBG) laser peak. The stimulation response of tapered fiber-based liquid-crystal microspheres to organic vapors causes a modification of the laser peak wavelength with increasing gas concentration. In addition, laser emission generated by tapered fiber-based liquid-crystal microspheres is expected to be used in fields such as microenvironmental biosensing.