In this study, spatial coherence tunable random lasing is proposed by designing a random laser with separate coupling configuration between the gain medium and the scattering part. By using the polymer dispersion liquid crystal (PDLC) film with tunable scattering coefficient for supplying random scattering feedback and output modification, red, green and blue random lasers are obtained. By applying or removing electric field to manipulate the scattering intensity of the PDLC film, intensity and spatial coherence of these random lasing are then switched between the high or low state. This work demonstrates that controlling the external scattering intensity is an effective method to manipulate the spatial coherence of random lasing.

Random lasers with low spatial coherence have important potential applications in speckle‐free imaging and displaying. Here, an angular spectra (AS) tunable random laser is proposed through directly coupling a microcavity with a commercial optical fiber. The local in‐plane AS distributions of the random lasing can be separately tuned by selectively using coupling filtering, free transmission, and intensity modulation. The obtained random lasing has the characteristics of non‐polarization and ring AS with distribution tunability. The unique properties endow the lasing as a promising illumination source for biological imaging. An excellent image with speckle‐free and high contrast is thus achieved with a maximal contrast improvement factor of 638% relative to that under the common white lighting. The results indicate that the designed AS‐tunable random laser has great application values in the fields of biological imaging, display, integration optics, and optical physics.