Wavelength-swept green random laser enables non-mechanical beam steering

Beam steering technology, with its flexible directionality, holds significant application value in free-space optical communication, LiDAR, advanced manufacturing, medical laser surgery, and so on. However, conventional methods achieving beam steering face various challenges: mechanical regimes, fixed operating wavelengths, and—specifically—a lack of tunable light sources in the blue-green spectral band (450 to 550 nm), which is recognized as the optimal transmission window for underwater wireless optical communication (UWOC) and the most efficient wavelength band for metal and battery manufacturing. With the aid of broadband feedback of Rayleigh backscattering and the acousto-optic modulation device-induced wavelength selectivity, we demonstrate, to the best of our knowledge, the first continuously wavelength-swept random fiber laser, which operates across the 1040 to 1090 nm spectral range, featuring a simple architecture, stable temporal output, and electrically controlled spectral sweeping properties. By employing a chirped periodically poled lithium niobate crystal for broadband phase matching, we extend the operational wavelength to the green band through second-harmonic generation. Furthermore, spectral-to-spatial mapping of this wavelength-swept green random laser enables beam steering, achieving an angular range of ∼1.8 deg and a minimum angular resolution of ∼0.021 deg. We anticipate that this wavelength-swept green random laser and its empowered beam steering technology will benefit applications such as UWOC and advanced manufacturing.