Multifunctional optoelectronic device based on graphene-coupled silicon photonic crystal cavities

Abstract

We present a hybrid device based on graphene-coupled silicon (Si) photonic crystal (PhC) cavities, featuring triple light detection, modulation, and switching. Through depositing single-layer graphene onto the PhC cavity, the light-graphene interaction can be enhanced greatly, which enables significant detection and modulation of the resonant wavelength. The device is designed to generate a photocurrent directly by the photovoltaic effect and has an external responsivity of ∼14 mA/W at 1530.8 nm (on resonance), which is about 10 times higher than that off-resonance. Based on the thermo-optical effect of silicon and graphene, the device is also demonstrated in electro-optical and all-optical modulation. Also, due to the high-quality (Q) factor of the resonate cavity, the device can implement low threshold optical bistable switching, and it promises a fast response speed, with a rise (fall) time of ∼0.4 μs (∼0.5 μs) in the all-optical switch and a rise (fall) time of ∼0.5 μs (∼0.5 μs) in the electro-optical hybrid switch. The multifunctional photodetector, modulator, and optical bistable switch are achieved in a single device, which greatly reduces the photonic overhead and provides potential applications for future integrated optoelectronics.

Black Phosphorus Photodetector Enhanced by a Planar Photonic Crystal Cavity

“…There are several works also reported on cavity-enhanced 2D material photodetectors. Here, the cavity-enhancement factor obtained from the fabricated BP photodetector is superior to the previous reports. − With an on-resonance optical excitation, the photoresponsivity is calculated as 7.8 mA/W under the zero-bias condition.…”

Tuning of Graphene-Based Optical Devices Operating in the Near-Infrared

“…It should also be noted that ring or disk modulators (in contrast to the Mach-Zehnder modulator [9,18] or planar photonic crystal nanocavity-based modulator [20]) are sensitive to temperature fluctuations [64]. In References [14,65], reliable athermal operation of the modulator without a noticeable change in the speed characteristics of the device at high temperatures up to 145 °C is presented, which does not close the question of the effect of temperature on the wavelength tuning. This point is related to the effect of heat transfer-graphene electrodes are connected to the dielectric materials, which includes other dielectric materials such as Si3N4 or Si.…”

“…(1a) Electrolyte/ion-gel-Graphene-Waveguide+PhC Cavity (EGWC), Figure 6c, is the PhC Nanocavity structure, which is located under the graphene electrode [65] and, in some cases, the capacitor insulator is located on top (electrolyte or ion-gel) [7,19,20] (partly a subgroup of GIW).…”

“…In other cases, it is necessary to consider the thickness of the layers of the graphene-based capacitor. For example, a dielectric with a thickness of 90 nm [8] or 120 nm [65] between two layers of graphene causes a weak electrostatic bond, which is expressed in high applied voltages (from −40 V to 40 V). In this regard, the boundary value of D G may be 90 nm, but the optimal value will be in the range <20 nm.…”

Recent advances in density functional theory approach for optoelectronics properties of graphene

“…Currently, graphene-based heterostructures are being tested in optical communication satellites, superfast electronics, and photodetectors [ 171 ]. However, accurate and transferable DFT and ML models to determine the strong anisotropic tensor in the overall optical response of graphene heterostructures are required to facilitate their implementation in real-world optical systems [ 385 , 386 ].…”