Angular Spectra Tunable Random Lasing for High Contrast Imaging

Abstract

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.