Weak lasing in one-dimensional polariton superlattices

Significance Bose–Einstein condensation of polaritons in periodically modulated cavities is a very interesting fundamental effect of the physics of many-body systems. It is also promising for application in solid-state lighting and information communication technologies. By a simple microassembling method, we created periodically modulated polariton condensates at room temperature, and observed the stabilization of the coherent condensate due to the spontaneous symmetry-breaking transition. This manifests a previously unidentified type of phase transition, leading to a novel state of matter: the weak lasing state. The optical imaging in both direct and reciprocal space provides clear evidence for the weak lasing in the specific range of the pumping intensities.