Excitation and lasing of whispering gallery modes in dye doped microspheres at the tip of a microstructured optical fiber and application for a sensitive dip sensor architecture

Abstract

A new concept for exciting whispering gallery modes (WGMs) using small core microstructured optical fibers (MOFs) is presented. Here a 10 μm spherical dye doped micro resonator was positioned onto the tip of the MOF, and the application of this device for refractive index sensing applications is presented. With this configuration, both the excitation and collection efficiency of the WGM modulated fluorescence spectra of the dye are found to be greatly improved compared to the more traditional excitation scheme in which the resonator is attached to a glass slide and excited using a confocal microscope. This novel MOF-tip configuration provides a more compact and robust architecture for in vivo/vitro biosensing applications. It is also shown that the same architecture can be used to operate the dye doped resonator beyond its lasing threshold, resulting in improved performances. © 2012 SPIE.