Dual modulation digital laser for generating vortex beams with tunable orbital angular momentum

•· A cost-effective digital laser configuration with dual-phase modulation using only single Spatial Light Modulator.•Dynamically generating high-quality vortex beams, Laguerre-Gaussian modes, with tunable orbital angular momentum.•A dual-phase modulation expanding the possibilities for intracavity beam shaping in Digital lasers. The development of digital lasers is limited by the fact that digital laser cavities can only provide a round-trip single-time intra-cavity phase modulation for the oscillating light field in the laser cavity, which limits the capability of generating structured light fields, such as light field type and quality. This paper presents a digital laser configuration of a cost-effective laser cavity design for generating orbital angular momentum (OAM) laser beams, which provides two controllable intra-cavity phase modulations by utilizing a single spatial light modulator (SLM). The experiments demonstrated that high-quality vortex beams with controllable OAM and intensity profiles are successfully generated in the proposed digital laser by employing dual spiral phase modulation in the laser cavity. The vortex Laguerre-Gaussian mode of topological charge value from 1 to 5 of high mode purity over 90% are obtained experimentally in this study. With two controllable intra-cavity phase modulations, this novel digital laser design not only presents a flexible solution for tailored OAM beam generation, but also extends the possibilities for advancing the generation of complex structured beam with digital lasers.