Fig. 2: Optical and electronic properties of the resonant electro-optic modulators.

a An array of metallic stripes with h_Au = 40–50 nm is patterned onto a quartz substrate and covered by a layer of organic electro-optic molecules JRD1 (see inset) mixed with PMMA of optical constants as shown in b. The electro-optic effect is accomplished by applying a poling bias to the film using the interdigitated array as described in the “Methods” section. The opposite direction of the poling field in adjacent periods is used to engineer an overall periodically poled film with alternating r₃₃ (blue) and −r₃₃ (red) at the nanoscale. Considering also the driving RF or DC fields, an overall homogenous refractive index change Δn is achieved in all unit cells (green, see inset). The frequency-dependent electrical characteristics are modeled by a simplified equivalent circuit from R_w, R_g, R₀, and C_g. c The array of metallic stripes spaced by w_field = 0.8−1.4 μm (displayed in different colors) sustain guided mode resonances inside the layer of JRD1:PMMA. They result from light scattered into different grating orders being guided in the slab formed by the air-JRD1:PMMA-quartz stack and subsequently reemitted. d Current–voltage characteristics of the junction feature bi-directional Schottky barriers formed at the metal-organic interface. The current is below 100 nA throughout the entire electro-optic tuning range up to the poling voltage of 100 V at w_gap = 1.2 μm. e The poling field has a strong component in the z-direction, as shown by the field plot. The arrows indicate the direction and magnitude of the poling field. f The optical characteristics of the guided mode resonances are characterized experimentally and compared to the simulated results at perfectly normal incidence, which reproduce well the resonant wavelengths of the three modes. The low quality factor and depth of mode II. and III. in both measurements and simulations are attributed to losses of JRD1:PMMA (ϵ_i in d) that increase dramatically close to 1100 nm.  g Electro-magnetic simulations from CST Microwave studio show the real part of the x-components and z-components of the three optical modes that form within the active layer in the wavelength range from 1100 to 1700 nm, given the geometric parameters. EO electro-optic, PP-JRD1:PMMA periodically poled JRD1:PMMA, Ti titanium, Au gold, R₀ external resistor, C_w resistance of one single metallic wire, R_g resistance between one single pair of metallic wires, C_g capacitance between one single pair of metallic wires.