Abstract

Whispering-gallery modes (WGM) can be found in liquid droplets, but there is also a variety of fabricated resonators such as Fabry-Perot, micro-spheres, ring, disk, bottle, capillary resonators and those based on optical fibre nanowires (for recent reviews, see e.g. Ref [1,2] and their respective references). Since the decade of 1990’s, oscillatory light losses or WGM produced in the coating of single-mode fibres (SMF) has been reported in the wavelength range from 600 nm to 1600 nm [3-5]. According to [3], when a SMF is bent, the evanescent field of the fundamental mode loses guidance and travels tangentially. This mode strikes and then keeps bouncing along the cladding/coating interface of the bend, assuming the evanescent field is fully reflected by the coating. In [4] it is considered the refractive index of the coating. By means of a ray-tracing model, they improved the model of [3] showing that, when the coating refractive index is similar or higher than that of the cladding, the WGM are refracted from the cladding to the coating and is reflected at the coating/air interphase going back to the core. All these previous experimental results and models have been carried out using SMF.

© 2015 IEEE