Numerical analysis of optical phase modulator operating at 2 μm wavelength using graphene/III–V hybrid metal-oxide-semiconductor capacitor

Abstract

We propose an optical phase modulator with a hybrid metal-oxide-semiconductor (MOS) capacitor, consisting of single-layer graphene and III-V semiconductor waveguide. The proposed modulator is numerically analyzed in conjunction with the surface conductivity model of graphene. Since the absorption of graphene at a 2 µm wavelength can be suppressed by modulating the chemical potential of graphene with the practical gate bias, the phase modulation efficiency is predicted to be 0.051 V·cm with a total insertion loss of 0.85 dB when an n-InGaAs waveguide is used, showing the feasibility of the low-loss, high-efficiency graphene/III-V hybrid MOS optical phase modulator, which is useful in the future 2-µm optical fiber communication band.

Efficient optical phase modulator based on an III–V metal-oxide-semiconductor structure with a doped graphene transparent electrode

“…Though several works suggest that graphene can also be used for its optical phase modulation characteristic, 30,31) the contribution of graphene to the phase modulation is expected to be no more than one-third in an III-V/graphene hybrid MOS modulator even at 5 nm SiO 2 gate oxide thickness due to the large electron-induced refractive index change in InGaAsP. 32) Therefore, the proposed modulator can keep a high modulation efficiency even when the contribution of graphene to the phase modulation becomes negligibly small in the case of the thick gate oxide. Hence, the phase modulation characteristic of graphene is not considered in the following analyses.…”