Simulations of single-mode laser emission along a waveguide connected to cross-coupled microresonators

Abstract

Objective: Single-mode operation is very important for laser emissivity; to exceed the emissivity of a single laser, the phase locking of all lasers in an array can be achieved only when the laser array is coupled and operated in single-mode. Methods: In this study, a single-mode laser emitted along the waveguide was realized through cross-coupling microspheres connected to a straight waveguide. Whispering-gallery modes were formed at the equators of the two microspheres when their resonance conditions were simultaneously satisfied. Compared with a single microcavity, the FSR of the coupled microcavities was significantly increased owing to the Vernier effect. Moreover, when the waveguide was coupled with the microspheres in the weak field of the resonance modes, the whispering-gallery modes near the equator were significantly suppressed, and a new quadrilateral mode was formed. Result: The energy in the coupling microspheres was concentrated in the stable quadrilateral mode and the Q factor was high (∼104). The single-mode laser energy in the waveguide accounted for 82 % of the total optical radiation energy of the device. This work has application prospects in laser switches and on-chip light sources.

Keywords

• Directional laser emission
• Microresonator
• Waveguide
• Quadrilateral resonance mode
• Whispering-gallery modes