https://www.selleckchem.com/products/dup-697.html Metasurfaces, acting as arrays of perfect nano-polarizers, provide a promising approach to manipulate the amplitude of an incident light at the sub-wavelength scale. In this Letter, we design and demonstrate continuous amplitude-modulated meta-fork gratings to generate optical vortex beams. More importantly, benefiting from the unique negative amplitude modulation, the unavoidable zero-order light that conventional amplitude-only elements always suffer disappears by carefully adjusting the orientation of each nanobrick. The dramatically dropped zero-order light with only 3% leakage energy verifies our design. With the advantages of continuous amplitude modulation, zero-order extinction, and super-high resolution, the proposed meta-fork grating will have a widespread application in integrated optical vortex manipulation and promote the emergence of many other amplitude-modulated nano-optical devices.Laser guide stars based on the mesospheric sodium layer are becoming increasingly important for applications that require correction of atmospheric scintillation effects. Despite several laser approaches being investigated to date, there remains great interest in developing lasers with the necessary power and spectral characteristics needed for brighter single or multiple guide stars. Here we propose and demonstrate a novel, to the best of our knowledge, approach based on a diamond Raman laser with intracavity Type I second-harmonic generation pumped using a 1018.4 nm fiber laser. A first demonstration with output power of 22 W at 589 nm was obtained at 18.6% efficiency from the laser diode. The laser operates in a single longitudinal mode (SLM) with a measured linewidth of less than 8.5 MHz. The SLM operation is a result of the strong mode competition arising from the combination of a spatial-hole-burning-free gain mechanism in the diamond and the role of sum frequency mixing in the harmonic crystal. Continuous tuning thr