Silicon microsphere whispering gallery modes excited by femtosecond-laser-inscribed glass waveguides

Abstract

We report on the coupling of whispering gallery modes in a 500-mu m-radius silicon microsphere to a femtosecond-laser-inscribed glass optical waveguide. The shallow glass waveguide with a large mode field diameter in the near-infrared is written at a depth of 25 mu m below the glass surface, resulting in a high excitation impact parameter of 525 mu m for the microsphere. The excited whispering gallery modes of the silicon microsphere have quality factors of approximately 10(5) in the 90 degrees elastic scattering and 0 degrees transmission. Integration of such spherical silicon microresonators on femtosecond-laser-inscribed glass waveguides is promising for photonic communication, computation, and sensing applications. (C) 2018 Optical Society of America.