All- Optical Control of Ultrahigh-Q Whispering Gallery Microspheres with Laser-Induced Graphene

We present a method for all-optical control of silica whispering- gallery-mode microspheres with laser-induced graphene (LIG). Polyimide ( PI) films are carbonized to LIG under CO2 laser irradiation. A 980 nm laser is used as a pump light to irradiate the LIG surface, and the transmission and reflection spectra of microcavities are studied. Experimental results show that the tuning scheme maintains a Q factor of approximately 10(8) throughout the tuning process, with a tuning range and sensitivity of approximately 1. 09 nm and approximately 8. 8 pm/mW, respectively. This scheme has the advantages of having no mechanical interference, an ultrahigh-Q factor, and a wide tuning range, thus extending all-optical tuning to applications in cavity quantum dynamics, nonlinear optics, and low- threshold lasers.