Dual Phase Modulation Digital Lasers: Advances in Structured Light Sources

The digital laser is famous for digitally controlling the laser modes and real-time selecting not only cavity modes but arbitrary spatial modes from the cavity. Despite these capabilities, the capability of digital lasers is constrained by single-step phase modulation, resulting in compromised beam quality when generating complex spatial modes directly from the laser system. This study addresses these challenges by introducing a novel digital laser configuration featuring two adjustable phase boundaries designed specifically to overcome the limitations of conventional setups. Moreover, the proposed configuration utilizes only one spatial light modulator (SLM) panel for the implementation of both adjustable phase boundaries, ensuring not only a compact form factor but also an efficient design. Experiments confirm the new configuration can generate vortex beams with controllable over both topological charge and intensity profiles with high quality. The Laguerre-Gaussian modes generating from this novel cavity have high mode purity, above 90%. This digital laser configuration also can generate several vortex array which formed by superposition of cavity modes, Hermite-Gaussian modes, with specific phase shift. Moreover, the versatility of this digital laser configuration extends beyond vortex beams, encompassing the generation of all kind of nondiffracting beams, including the Parabolic-Gaussian beam previously unattainable directly from laser cavities. This innovative digital laser configuration represents a promising solution for customizable structured beam laser, with wide-ranging applications such as optical trapping, optical communication, material processing and microscopy.