Studies of geometrical profiling in fabricated tapered optical fibers using whispering gallery modes spectroscopy

This paper experimentally demonstrates a method for geometrical profiling of asymmetries in fabricated thin microfiber tapers with waist diameters ranging from ∼10 to ∼50 µm with submicron accuracy. The method is based on the analysis of whispering gallery mode resonances excited in cylindrical fiber resonators as a result of evanescent coupling of light propagating through the fiber taper. The submicron accuracy of the proposed method has been verified by SEM studies. The method can be applied as a quality control tool in fabrication of microfiber based devices and sensors or for fine-tuning of microfiber fabrication set-ups.