Free-Space Indium Tin Oxide Electro-Optic Transmission\nModulator

Free-space electro-optic\nmodulators provide control over the transverse\ntransmission of an incident beam and are essential elements in metrology,\nsensing, and free-space communication. We present a novel modulator\nthat leverages the free-carrier dispersion effect in indium tin oxide\nin combination with a plasmonic grating to achieve significant amplitude\nmodulation with the potential to locally modify the optical signal\nat micrometer scales and high operation speeds. Subwavelength optical\nconfinement and good spatial overlap of both grating resonance plasmonic\nmodes and electrostatic fields created by the gold grating enable\na notable modulation depth (∼0.5%) within a sub-10 nm active\nlayer at the free-space wavelength of 1.55 μm. Due to the wide\nresonance formed by a plasmonic grating, broadband operation over\n100 nm is demonstrated. Our monolithic indium tin oxide electro-optic\nplatform enables a wide range of cost-effective light modulation applications\nthat demand smaller footprints, faster operation, and higher robustness\nthan in currently available state-of-the-art spatial light modulators.