Research Progress of Low-Coherence Laser

Laser has been widely used because of its high coherence, high directivity, and good monochromaticity. However, the high coherence of laser will cause serious speckle effect, which leads to great resistance to its application in the display and imaging field. By introducing the innovation of laser cavity geometry and laser oscillation feedback mechanism, and controlling the number of lasing modes and modes spatial distribution, highcoherence lasers can be developed into low-coherence lasers, which arc gaining more and more attention. In this review, we elaborated on the development history, generation mechanism, and existing problems of five lowcoherence lasers including random lasers, degenerate cavity lasers, chaotic cavity semiconductor lasers, nearconcentric cavity semiconductor lasers, and dumbbell-shaped cavity semiconductor lasers. This review provides a decision-making reference for the development direction and application of low-coherence lasers.