Abstract
Indium tin oxide (ITO) platform is one of the promising solutions towards state-of-the-art integrated optical modulators for silicon photonics applications. We demonstrate the way to obtain both high extinction ratio and low insertion loss electro-optic modulation with ITO-based film stack. By investigating e-beam evaporated 20 nm-thick ITO films with amorphous, heterogeneously crystalline, homogeneously crystalline with hidden coarse grains and pronounced coarsely crystalline structure, a low carrier concentration (from 1·1020 to 2·1020 cm-3) is achieved. The mechanism of oxygen migration in ITO film crystallization is proposed based on morphological features observed under low-energy growth conditions. We compare three electro-optic modulator active elements (current-voltage and optical characteristics) and reach strong ITO dielectric permittivity variation induced by charge accumulation/depletion (Δn = 0.199, Δk = 0.240 at λ = 1550nm under ±16V). Our simulations and experimental results demonstrate the unique potential to create integrated GHz-range electro-optical modulators with sub-db losses.
Complete achromatic and robustness electro-optic switch between two integrated optical waveguides