Spectral cleaning and output modal transformations in whispering-gallery-mode microresonators

Mohd Nasir, Mohd Narizee, Murugan, G. Senthil and Zervas, Michael (2016) Spectral cleaning and output modal transformations in whispering-gallery-mode microresonators. Journal of the Optical Society of America B, 33 (9), 1963-1970. (doi:10.1364/JOSAB.33.001963).

Record type: Article

Abstract

A systematic study on the effects of microtaper fiber diameters on the spectral characteristics of a whispering-gallery-mode (WGM) micro-bottle resonator (MBR) is presented. Progressively cleaner and simpler spectra of the MBR were observed when the utilized microtaper fiber waist diameter (D_t) was increased from 2µm to 10µm. The maximum transmission depth at resonance varies with different microtaper fiber utilized from ~20 dB (D_t = 2µm) to ~4 dB (D_t = 10µm). The loaded Q-factors were observed to be unaffected by the increase of D_t with values of > 10⁶ being measured in all cases. Mode transformation of MBR was also experimentally investigated and compared to a microdisc FDTD simulation by studying near-field images of the output beam on the waist of the microtaper fibers. For the first time, experimental observation of mode transformation from LP₀₁ to LP₁₁ across scanned WGM resonances is being reported.