Abstract: Micro-lasers with micro/nano scale cavities have mode volume at wavelength or sub-wavelength scale, characterized by small size, easy integration, low threshold, wide band, and tenability． Micro-lasers play a key role in the generation, transmission, coupling, modulation, detection and other functions of optical information on photonic chips, an important frontier in the field of micro/ nano optics． Applications of micro-lasers are related to their optical field characteristics． To realize multi-functional application of micro-lasers, studies on optical field modulation have been conducted, on theory, experimental and device application． Here, research progress of micro-lasers is summarized, particularly of optical field modulation and applications． Modulating methods based on pumping light, gain and micro-cavity are emphatically described． The applications of micro-lasers in sensing, anti-counterfeiting, imaging and display fields are summarized． Future research directions are discussed.