Dynamical radiation pressure effects in cavity optomechanical systems give rise to self-sustained oscillations or ‘phonon lasing’ behavior, producing stable oscillators up to GHz frequencies in nanoscale devices. Like in photonic lasers, phonon lasing normally occurs in a single mechanical mode. We show here that mode-locked, multimode phonon lasing can be established in a multimode optomechanical system through Floquet dynamics induced by a temporally modulated laser drive. We demonstrate this concept in a suitably engineered silicon photonic nanocavity coupled to multiple GHz-frequency mechanical modes. We find that the long-term frequency stability is significantly improved in the multimode lasing state as a result of the mode locking. These results provide a path toward highly stable ultracompact oscillators, pulsed phonon lasing, coherent waveform synthesis, and emergent many-mode phenomena in oscillator arrays.

European Union Horizon 2020 , The Netherlands Organisation for Scientific Research (NWO)
Photonic Forces

Mercadé, L., Pelka, K., Burgwal, R., Xuereb, A., Martínez, A., & Verhagen, E. (2021). Floquet Phonon Lasing in Multimode Optomechanical Systems. Phys.Rev.Lett., 127(7), 073601: 1–7. doi:10.1103/physrevlett.127.073601