No abstract

Optical vortex arrays with multiple singularities arranged in distinct lattice structures provide more flexibility in trapping or manipulating microparticles, large-capacity optical communications and high-security information processing, and optical modulation. An efficient high-power compact laser with singularity-tunable vortex-array distribution is crucial for practical applications. Here, we directly generate various vortex arrays with tunable singularities from 1 to 10 in a microchip laser pumped with a tilted annular beam. Formation of vortex arrays in the microchip laser is achieved by manipulating the gain distribution in an Yb:YAG crystal by controlling the tilt angles and pump power. Efficient high-power laser operation with output power of 2.01 W and optical efficiency of 24.5% is obtained for a vortex array with 10 singularities. The pump-power-dependent saturated population inversion distribution plays a key role in generating vortex arrays formed with multi-transverse modes oscillating simultaneously in transverse-mode locking. The good agreement between theoretically simulated transverse patterns, phases and interference patterns for the vortex arrays and experimentally obtained results provides a solid foundation for developing efficient compact microchip lasers for generating vortex arrays by manipulating gain distribution in a thin medium pumped with a tilted annular beam.

Crisscross vortex arrays have well-defined arrangements of vortices, are ideal light sources for efficiently manipulating multiple microparticles, assemble microprocessing, and optical communications. However, the output power of crisscross vortex arrays is low and laser operating wavelength is limited by the narrow emission spectrum of Nd:YVO 4 crystal.The operating wavelength of optical vortex arrays expands their applications and various methods such as frequency doubling; stimulated Raman scattering (SRS) effect was applied for

High‐order Hermite–Gaussian (HG) lasers oscillating at multiple wavelengths are extensively needed for generating vortex lasers carrying orbital angular momentum (OAM), which have wide applications on optical communication, high capacity storage, and high resolution imaging. Off‐axis pumping or off‐axis resonator has been used to generate high‐order HG0,n lasers, however, low optical efficiency limits practical applications of these lasers. Here, direct generation of multiple wavelength high‐order HG0,n lasers in a rectangular beam pumped Raman microchip laser constructed with Yb3+:Y3Al5O12 (Yb:YAG) and yttrium vanadate (YVO4) crystals is demonstrated. The order n of HG0,n mode lasers can be tuned from 1 to 9. HG0,n (n > 3) mode Raman lasers oscillate at multiple wavelengths and shift to longer wavelength with n. The output power is 137 mW for multiwavelength HG0,9 mode Raman laser when the input pump power is 2.7 W. The optical conversion efficiency is as high as 5.1%. Excellent beam quality with My2 close to theoretical values (My2 = 2n+1) for high‐order HG0,n lasers has been achieved. Topological charge tunable Laguerre–Gaussian (LG) vortex lasers with high beam quality are generated from HG0,n mode lasers with an astigmatic mode converter. This work demonstrates that rectangular beam pumping is an effective method for developing efficient multiwavelength high‐order HG0,n mode Raman lasers.

High beam quality, highly efficient radially polarized vector vortex beam has been generated in a Yb:YAG microchip laser pumped with an annular beam formed with a hollow focus lens. The output power of 2.15 W has been achieved at the absorbed pump power of 3.53 W. The optical-to-optical efficiency is 60.9%. The radially polarized vector vortex lasers working at 1030 nm, 1050 nm, 1030/1050 nm dual-wavelength depending on applied pump power. High polarization purity with degree of polarization of over 91% has been achieved for radially polarized vector vortex lasers. Our work provides an effective method for developing compact wavelength tunable, radially polarized vector vortex lasers.