Spatial light modulators with gratings use programmable diffraction or phase control to modulate light with high speed, resolution, and efficiency.

Grating Light Valve (GLV)

The Grating Light Valve (GLV) is a MEMS-based SLM consisting of thousands of micro-ribbons on a silicon chip. By electronically controlling the displacement of these ribbons, the GLV acts as a programmable diffraction grating, modulating laser light in amplitude and phase. When active ribbons are co-planar with static ribbons, light reflects normally; when displaced by a quarter-wave, the reflected light interferes destructively, scattering into diffraction orders. Intermediate displacements allow analog grayscale control, enabling precise light modulation for imaging and display applications .

Piezoelectrically Actuated Resonant Waveguide Gratings

High-speed SLMs can also be realized using piezoelectrically actuated resonant waveguide gratings on silicon nitride. These devices support >100 MHz modulation speeds and high extinction ratios (>20 dB), with individually addressable pixels. They are suitable for visible to near-infrared wavelengths and applications requiring multimodal optical control, such as quantum information processing, laser ranging, and AR/VR .

Liquid Crystal SLMs with Grating Calibration

Liquid crystal SLMs (LC-SLMs) can implement grating-based phase modulation. Techniques like vortex-grating lateral-shearing interferometry allow full-pixel grayscale-phase calibration, improving modulation accuracy and stability. This enables precise control of light phase and amplitude for holography, beam shaping, optical trapping, and communication .

Graphene-on-High-Contrast Grating SLMs

Emerging SLMs integrate graphene with high-contrast gratings (HCGs) to modulate surface-normal reflection. By applying voltage to graphene layers, these devices achieve high extinction ratios and can be fabricated in large 2D arrays using CMOS-compatible processes. They offer potential for MHz-speed operation, free-space optical modulation, and scalable, low-cost applications in imaging and optical interconnects .

Applications

SLMs with grating structures are widely used in:

• Laser beam shaping and switching
• Holographic displays and imaging
• Quantum optics and atom-based experiments
• Optical communication and interconnects
• AR/VR and adaptive optics These devices leverage the wave nature of light and grating interference to achieve high-speed, high-resolution, and tunable modulation, making them versatile tools in both research and industrial photonics.