Fano-Like Line Shape and its Tuning Effect in a Double-Handle Whispering Gallery Mode Microsphere Resonator

A double-handle whispering gallery mode (WGM) microsphere resonator is proposed and used to generate Fano-like line shape. In the coupling state, the mutual interference between the WGMs is achieved and tuned by controlling the strain along two handles. The difference in Q value between the involved modes contributes to an asymmetric Fano-like line shape. Furtherly, the Fano-like line shape could be finely tuned and moved by controlling the axial strain from 0 to 186.56 mu & varepsilon;. In the tuning process, the tuning efficient, which can also be considered as strain sensitivity, is about 10(-2) pm/mu & varepsilon;. In addition, the WGMs simultaneously redshift when the temperature raised from 30.7 degrees C to 41.5 degrees C, rendering the line shape nondeformable. This tuning method has high stability and simplicity in controlling Fano resonance. The different responses to strain and temperature make it possible to tune the resonance both in line shape and wavelength. It has high application value in optical switch, electro-optical modulator and high-resolution sensor.