Equilibrium transition induced by boundary perturbation in a random optical system

Random optical systems have been widely investigated due to their abundant physical effects, including numerous degrees of freedom and equilibrium states. Whereas the boundary perturbation can disturb the dynamical behavior of the equilibrium states and lead to a series of unexplored evolution, here we unveil the equilibrium transition induced by boundary perturbation in random fiber lasers through introducing a laser-feedback process. In this typical random optical system, the predominant role of random scattering can be manipulated by a laser-feedback process that serves as boundary perturbation, causing the transition of the equilibrium state and output properties of the laser. On this basis, the photon lifetime can also be reduced, presenting huge potential in highly sensitive non-contact sensing with a detectable minimum feedback power of 12.08 fW and a detection distance of 130 km. Our work provides a new perspective in deepening the understanding of intrinsic mechanisms in random systems and broadens the underlying applications, including modal manipulation and high sensitivity measurement.