Introducing phase transition materials to random systems provides a promising route to create new optoelectronic functionalities of random lasers. Here, a phase transition random laser with switchable lasing modes is reported, which is designed with a thermoresponsive hydrogel as scattering medium. By manipulating the phase transition in hydrogel, random lasing modes can be switched reversibility between incoherent and coherent random lasing. The phenomenon derives from the changing of light scattering properties in different phase states, thus affecting the optical feedback path of random lasing. Besides, based on its controllable and easily detectable time-domain characteristics, the phase transition random laser is applied in information encoding and transmission. It is the first time that the transition from coherent to incoherent random lasing is observed by varying the sample phase states. This work will inspire the design and application of novel random lasers in photoelectric device.

Fig. 1. Design and working principles

Fig. 2. Dynamical control of random lasing modes in PTRLs.

The above results, titled "Tunable random lasers via phase transition for information encryption", were published in the internationally renowned journal Optics Express. Tong Junhua, a young teacher in our college, is the first author of the article, Lin Chengyou is the corresponding author, and the College of Mathematics and Physics of Beijing University of Chemical Technology is the first signatory.

Paper link:https://doi.org/10.1364/OE.497982.