Carrier-Induced Optical Modulation in Si-ITO based Ring Resonator with Improved Tuning Efficiency

Abstract

Reconfigurable, high-speed, and energy-efficient modulators are central to the advancement of next-generation optical communication and signal processing systems. Here, we demonstrate a micro-ring modulator based on semiconductor heterojunctions of silicon and indium tin oxide (ITO). The device exploits field-effect induced refractive index tuning in accumulation layer of ITO which has strong plasma dispersion and epsilon near zero (ENZ) effect enabling efficient electro-optic modulation with ultra-compact device footprint. A voltage-tunable spectral range with a wavelength shift of 1 nm, corresponding to EO tuning efficiency of 0.5 nm/V is reported. The 20 μm long device achieves a high extinction ratio of 21 dB and electrical bandwidth of 26.5 GHz which enables the high-speed operation of more than 50 Gbps while maintaining low energy consumption of 0.112 pJ/bit, positioning the device among the most efficient integrated modulators based on ITO. The reported results establish the Si-ITO ring modulator as a compact, CMOS-compatible platform for wavelength-selective modulation and tunable filters with potential for applications in microwave photonic signal processing, and neuromorphic photonic computing applications. © 1983-2012 IEEE.