Terahertz Spatial Light Modulator with Digital Microfluidic Array

Abstract We propose a radically different idea for spatial light modulation in broadband terahertz range compared to existing solutions. We utilize the high and broadband absorption of water for THz spatial modulation by means of programmable digital microfluidic droplet array. The structure is transparent in the THz region as it has coplanar electrode arrangement without conducting top electrode. The array has two reservoirs to work as a closed system to move around droplet arrangements. A microfluidic chip has been manufactured to be used in reflective setup. This proof of concept is presented here including a 10x10 array demonstrated at 0.48THz with near 100% contrast. The possible usage of the solution is e.g. imaging using compressed sensing. The architecture is applicable to droplet spectral analysis as well due to its transparent top plate.

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