High resolution multispectral spatial light modulators based on tunable Fabry-Perot nanocavities

Spatial light modulators (SLMs) are the most relevant technology for dynamic wavefront manipulation. They find diverse applications ranging from novel displays to optical and quantum communications. Among commercial SLMs for phase modulation, Liquid Crystal on Silicon (LCoS) offers the smallest pixel size and, thus, the most precise phase mapping and largest field of view (FOV). Further pixel miniaturization, however, is not possible in these devices due to inter-pixel cross-talks, which follow from the high driving voltages needed to modulate the thick liquid crystal (LC) cells that are necessary for full phase control. Newly introduced metasurface-based SLMs provide means for pixel miniaturization by modulating the phase via resonance tuning. These devices, however, are intrinsically monochromatic, limiting their use in applications requiring multi-wavelength operation. Here, we introduce a novel design allowing small pixel and multi-spectral operation. Based on LC-tunable Fabry-Perot nanocavities engineered to support multiple resonances across the visible range (including red, green and blue wavelengths), our design provides continuous 27 r phase modulation with high reflectance at each of the operating wavelengths. Experimentally, we realize a device with 96 pixels (similar to 1 mu m pitch) that can be individually addressed by electrical biases. Using it, we first demonstrate multi-spectral programmable beam steering with FOV similar to 18 degrees and absolute efficiencies exceeding 40%. Then, we reprogram the device to achieve multi-spectral lensing with tunable focal distance and efficiencies similar to 27%. Our design paves the way towards a new class of SLM for future applications in displays, optical computing and beyond.

Automated summary

This study presents a novel design of spatial light modulators (SLMs) that enable small pixel and multi-spectral operation. The design utilizes LC-tunable Fabry-Perot nanocavities to support multiple resonances across the visible range, allowing for high reflectance and continuous phase modulation. Experimental results demonstrate the device's programmable beam steering and lensing capabilities with high efficiency. This design opens up new possibilities for SLM applications in displays, optical computing, and beyond.