Generation of dark hollow beam with phase-only liquid crystal spatial light modulator

To improve the power efficiency of the laser system, it is necessary to transform Gaussian intensity distribution to dark hollow intensity distribution. The phase-only liquid crystal spatial light modulator (LC-SLM) has been used to transform a quasi-Gaussian beam to a dark hollow one. The phase distribution of the shaping system was derived according to the energy conservation law and the constant optical length principle. The influences of input beam waist and shape on shaping effect were discussed based on numerical simulation. The generation of the dark hollow beam has been realized experimentally with the phase-only LC-SLM, and the conversion efficiency was larger than 99%．