High-transmission electrowetting light valves

High-efficiency spatial light modulation has been demonstrated for transmissive electrowetting (EW) light valves (ELVs). The ELV structure consists of a competitive oil/water-on-dielectric EW cell fabricated on an optically transparent substrate. ELVs are configured as display devices by attaching a diffuse backlight powered by white converted InGaN light emitting diodes. The oil film contains ∼1wt.% nonpolar organic chromophores which absorb with near-neutral optical density across the visible light spectrum. Using the EW effect, spatial light modulation is achieved as the water layer locally displaces the oil film. The transmissivity of the cell can be modulated from ∼5% (zero bias) to >80% (∼30V). ELV switching speed depends on cell size, typically ∼10–100ms for 1 and 3mm2 cells. Additional optical enhancement can decrease the off-state ELV transmissivity to <1%.