Cascaded Brillouin lasing in a suspended silicon racetrack micro-ring pumped by external fiber loop

Brillouin lasing featured by narrow linewidth and wide tunability has been applied to sensing, coherent communication and microwave photonics. Here, we demonstrate a cascaded Brillouin lasing in the integrated silicon racetrack micro-ring pumped by the external fiber loop. The elaborate micro-ring can tightly confine both optical and acoustic fields, and enable the efficient generation of cascaded forward stimulated Brillouin scattering. Under the high external pump power, we observe the cascaded Brillouin lasing up to 3 Stokes order and 3 anti-Stokes order. Our experiment provides a new method to realize a cascaded Brillouin lasing in on-chip platform.