Fano-Like Spectrum With a Quasi-Independent Tuning of Slope Ratio Based on HE Mode Components Coupled Whispering Gallery Mode

Narrow bandwidth Fano-like spectrum was demonstrated with tunable slope ratio, stable intensity extremums and high extinction ratio based on HE mode components coupled whispering gallery mode. The theory was presented with calculations to analyze the spectra profiles with slope ratio and extremums of the transmission included. In the experiment, spectra with a modified positive slope ratio from 49.2 dB/GHz to 197.0 dB/GHz, and a negative slope ratio from −71.9 dB/GHz to −230.2 dB/GHz were achieved with the extremums varied less than 10%. The configuration could be widely applied in optical sensing, optical switching and dispersion control.