2D materials-enabled optical modulators: From visible to terahertz spectral range

Abstract

Two-dimensional (2D) materials with layered structures have a variety of exceptional electronic and optical attributes for potentially developing basic functions of light wave technology from light-emitting to -modulating and -sensing. Here, we present state-of-the-art 2D materials-enabled optical intensity modulators according to their operation spectral ranges, which are mainly determined by the optical bandgaps of the 2D materials. Leveraging rich electronic structures from different 2D materials and the governed unique light–matter interactions, the working mechanisms and device architectures for the enabled modulators at specific wavelength ranges are discussed. For instance, the tunable excitonic effect in monolayer transition metal dichalcogenides allows the modulation of visible light. Electro-absorptive and electro-refractive graphene modulators could be operated in the telecom-band relying on their linear dispersion of the massless Dirac fermions. The bendable electronic band edge of the narrow bandgap in few-layer black phosphorus promises the modulation of mid-infrared light via the quantum-confined Franz–Keldysh or Burstein–Moss shift effect. Electrically and magnetically tunable optical conductivity in graphene also supports the realizations of terahertz modulators. While these modulators were demonstrated as proof of concept devices, part of them have great potential for future realistic applications, as discussed with their wavelength coverage, modulation depth, insertion loss, dynamic response speed, etc. Specifically, benefiting from the well-developed technologies of photonic chips and optical fibers in telecom and datacom, the 2D materials-based modulators integrated on these photonic structures are expected to find applications in fiber and chip optical communications. The free-space mid-infrared and terahertz modulators based on 2D materials can expect application in chemical bond spectroscopy, free-space communications, and environment/health sensing.

Recent advances in enhancing the photodetector performance of 2D materials by combining them with organic thin films

“…2,28,29 The two-dimensional condition makes it possible to achieve arbitrary stacking between any materials, which is completely unaffected by the lattice mismatch of traditional 3D materials, and exhibits highly compatible integration properties. 30 Therefore a large number of 2D materials have been applied in advanced optoelectronic devices, [31][32][33] including photodetectors, 1 optical modulators, 34 lasers, 35 and synaptic photonic chips. 36 In 2009, Xia et al prepared the first graphene photodetector, 1 which initiated the large-scale application of graphene in photodetectors.…”

Ultrafast All-Optical Modulation and Efficient Third-Harmonic Generation in Two-Dimensional Perovskite Heterostructures

“…Ultrafast all-optical modulation and efficient frequency conversion are highly required for a wide range of applications, including optical communication, microwave photonics, and quantum computing. − The optical modulation can be realized by the light–matter interactions via the electro-optic, acousto-optic, magneto-optic, thermo-optic, and mechano-optic effects, respectively. However, with the arrival of the 5G high-capacity information society, the optical modulators face challenges with the ever-increasing demands for modulation speed and bandwidth. , The all-optical modulation by controlling light with light can offer intrinsic advantages in terms of the operating speed and bandwidth, which is essential for ultrafast, broadband, and cost-effective optical signal processing .…”

Enhanced Asymmetric Light‐Plasmon Coupling in Graphene Nanoribbons for High‐Efficiency Transmissive Infrared Modulation

“…Mid-infrared free-space optical modulators, possessing the ability to regulate the amplitude, phase, and polarization of mid-infrared light, have been recognized as one of the most crucial devices in the fields such as infrared scene projection, infrared deception, infrared optical communication and hyper spectra imaging [1][2][3][4] The traditional digital micromirror based modulator, consisting of an array of individually switchable mirrors, can modulate the mid-infrared light in reflection mode by designing the infrared transparent optical window. [5,6] Nevertheless, due to the reflective geometry of this modulator, it is primarily served as a discrete component in an optoelectronic system and commonly requires extra optical elements such as beam splitters or polarizers to separate the incident and reflected light, making it difficult to shrink the size of the optoelectronic system to the chip level.…”