Stimulated Scattering in Supermode Microcavities: Single- or Dual-Mode Lasing?

Near-degenerate supermodes microlaser has drawn a lot of attention in the research of high-precision sensors, fundamental physic study, and the advanced light source. In the recent work on supermode microcacities, the experimentally observed beating phenomena of the stimulated Raman scattering, are regarded as the evidence of the dual-mode lasing. However, it theoretically contradicts the clamped pump filed guaranteed single-mode laser behavior of stimulated Raman scattering. In this work, the supermode stimulated Raman scattering has been studied in ultrahigh-Q whispering gallery microcavities. and it is the first time that its single-mode behavior is experimentally investigated due to the up to 37 dB side-mode suppression ratio (SMSR). In addition, the transient interference of the two supermode lasers switching is confirmed to cause the observed beating phenomena. Furthermore, this self-injection method can be adopted to adjust the lasing modes.