A novel characterization method is proposed to extract the optical frequency field-effect mobility (μop,FE) of transparent conductive oxide (TCO) materials by a tunable silicon microring resonator with a heterogeneously integrated titanium-doped indium oxide (ITiO)/SiO2/silicon metal–oxide–semiconductor (MOS) capacitor. By operating the microring in the accumulation mode, the quality factor and resonance wavelength shift are measured and subsequently used to derive the μop,FE in the ultra-thin accumulation layer. Experimental results demonstrate that the μop,FE of ITiO increases from 25.3 to 38.4cm2?V-1?s-1 with increasing gate voltages, which shows a similar trend as that at the electric frequency.

Transparent conductive oxides have attracted escalating research interest for integrated photonic devices and metasurfaces due to the extremely large electro-optic modulation of the refractive index by the free-carrier-induced plasma dispersion effect. In this paper, we have designed and fabricated a silicon microring resonator using an indium-tin oxide gate as the electric-tuning electrode. It achieved an ultralarge resonance wavelength tunability of 271 pm/V, which is obtained through the reduced width of the ring waveguide and a high-dielectric-constant HfO2 insulator. We demonstrated a broad resonance wavelength tuning range of over 2 nm with an ultrafast response time of less than 12 ns and near-zero static power consumption, which outperforms traditional thermal tuning.

Transparent conductive oxides have emerged as a new type of plasmonic material and demonstrated unique electro-optic (E-O) modulation capabilities for next-generation photonic devices. In this paper, we report an ultra-compact, broadband electro-absorption (EA) modulator using an epsilon-near-zero (ENZ) indium-tin oxide (ITO). The device is fabricated on a standard silicon-on-insulator platform through the integration with a 3 μm long, 300 nm wide gold plasmonic slot waveguide. The active E-O modulation region consists of a metal–HfO2–ITO capacitor that can electrically switch the ITO into ENZ with ultra-high modulation strengths of 2.62 and 1.5 dB/μm in simulation and experiment, respectively. The EA modulator also demonstrated a uniform E-O modulation with 70 nm optical bandwidth from 1530 to 1600 nm wavelength.