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

Abstract

We propose a III–V metal-oxide-semiconductor (MOS) optical modulator with graphene gate electrode along with the analysis of the modulation properties. With p-type doped graphene used as a transparent gate electrode, we can fully utilize the electron-induced refractive index change in an n-type InGaAsP waveguide with the reduction of the hole-induced optical absorption observed in a III–V/Si hybrid MOS optical modulator. Numerical analysis displays that up to the phase modulation efficiency of 0.82 V·cm and 0.22 dB optical loss for π phase shift can be achieved when the gate oxide thickness is 100 nm. With the elimination of the unnecessary parasitic capacitance found in the overlapping of graphene on the slab part of the waveguide, in conjunction with the high electron mobility in InGaAsP, the device also enables a modulation bandwidth of greater than 200 GHz.

Scaling photonic integrated circuits with InP technology: A perspective

“…126 Miniaturized modulators can be realized with the membranebased approach. By inserting a thin layer of dielectric in the middle of two electrically biased semiconductor layers, forming a capacitor, [127][128][129][130][131] efficient modulators by carrier accumulation are reported. This is not possible on substrate-based platforms since the optical mode is deeply shielded by the claddings.…”

“…127 Initial results show modest GHz-level modulation bandwidths, but a recent study has predicted a route to higher bandwidths. 129 Amplifiers and lasers miniaturization benefit from optical confinement enhancement with the membrane structure. A conceptual illustration is shown in Fig.…”