LCOS-SLM devices are a reflective type of pure phase Spatial Light Modulators (SLMs), based on Liquid Crystal on Silicon (LCOS) technology in which liquid crystal (LC) is controlled by a direct and accurate voltage, and can modulate a wavefront of light beam. The LCOS-SLMs are optimally designed to achieve high light utilization efficiency from various points of view, such as reflectivity, aperture ratio and diffraction noise due to the pixel structure. LCOS-SLM can be controlled via a PC using the Digital Video Interface (DVI), which is a standard interface for computer displays. The distortions in the LCOS chip, such as wavefront distortion and nonlinear response of the LC, are efficiently compensated by the contloller.Easy computer control, precise and linear phase modulation characteristics can be accomplished LCOS-SLM. They can also provide high diffraction efficiency and high light utilization efficiency.


The LCOS chip has a parallel-aligned nematic liquid crystal layer to modulate light. It only changes the phase of light without any change of intensity and rotation of polarization state. Phase modulation is changed according to the alignment of the LC. The LC alignment is controlled, pixel by pixel, using a CMOS backplane and a DVI signal via a PC.


LCOS-SLM is a pure phase SLM with high precision phase control. therefore, it has high diffraction efficiency close to the theoretical maximum. Left Figure shows images of diffracted spots in Pi Photonics, Inc., when a multi-level phase grating is formed in the X10468 and Right Figure shows typical diffraction efficiency characteristics. Here, diffraction efficiency is defined I1/I0, I1 is intensity of the 1st order diffraction spot, I0 is the intensity of the 0th order light when no pattern is displayed.

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LCOS-SLM:Liquid Crystal on Silicon - Spatial Light Modulator