Research on using phase-only spatial light modulator to realize amplitude modulation

Spatial light modulator (SLM) with pure phase can easily simulate a variety of phase diffraction elements, but phase-only SLM cannot simulate amplitude diffraction elements directly. Checkerboard method and blazed grating method are described to achieve amplitude modulation using phase-only SLM. A beam transformation system is built to demonstrate these methods. Experimental results show that the checkerboard method and blazed grating method can achieve excellent amplitude modulation using SLM with pure phase, which increase the range of applications of phase-only SLM. A new approach is also proposed to combine two Laguerre-Gaussian beams by a forked grating generated by the blazed gratings method.