Graphene-based integrated photonics for next-generation datacom and telecom

Abstract

Graphene is an ideal material for optoelectronic applications. Its photonic properties give several advantages and complementarities over Si photonics. For example, graphene enables both electro-absorption and electro-refraction modulation with an electro-optical index change exceeding 10 −3 . It can be used for optical add-drop multiplexing with voltage control, eliminating the current dissipation used for the thermal detuning of microresonators, and for thermoelectric-based ultrafast optical detectors that generate a voltage without transimpedance amplifiers. Here, we present our vision for graphene-based integrated photonics. We review graphene-based transceivers and compare them with existing technologies. Strategies for improving power consumption, manufacturability and wafer-scale integration are addressed. We outline a roadmap of the technological requirements to meet the demands of the datacom and telecom markets. We show that graphene based integrated photonics could enable ultrahigh spatial bandwidth density , low power consumption for board connectivity and connectivity between data centres, access networks and metropolitan, core, regional and long-haul optical communications.Photonics is poised to play an increasingly important role in ICT ( Fig. 1a), since the fixed high capacity links are largely based on photonic technologies. Photonic devices need to support ultra-large bandwidth operation, for example, 200 Tb s−1 in a single fibre[9] and >10 Tb s −1 cm −2 in integrated Si photonics chips [10]. To achieve this, the key components of Si photonics, photodetectors and modulators, need very high performances in terms of speed (≥25 Gb s −1 ), footprint (<1 mm 2 ), insertion loss (<4 dB), manufacturability (>10 6 pieces per year) and power consumption (<1 pJ bit −1 ). To date, these requirements have not been fulfilled in one system [11]. Furthermore, in terms of production volumes, photonics is not yet comparable to microelectronics [12], even if the increase in demand for optical networks would, by 2021, lead to an average global Internet Protocol (IP) traffic of 3.3 ZB (zettabytes), corresponding to an average usage data rate of ~800 Tb s −1 (refs[13,14]). In the context of the IoT[7], other applications, including infrared (IR) sensors, biosensors, environmental sensors, metrology, quantum communications and machine vision, will require even larger production volumes [13,15].The telecom network can be divided into three segments: access, aggregation and core (Fig. 1a). The access network is the interface between subscribers and the immediate service provider. The aggregation network aggregates all the input data streams from tributary access networks, converging towards the higher-level core network. The aggregation network includes local and metropolitan networks, which then converge to regional networks. A local area network (LAN) interconnects computers within a limited area, such as a residence, school, laboratory, university or office building. A metropolitan area network (MAN) interconnects us...

High-performance silicon−graphene hybrid plasmonic waveguide photodetectors beyond 1.55 μm

“…In contrast, two-dimensional materials provide a new and promising option for enabling active photonic devices on silicon [13][14][15][16] . In particular, currently graphene 14,15 and black-phosphorus (BP) [16][17][18][19] have been popular for realizing waveguide photodetectors on silicon. Recently, we reported a silicon-BP hybrid waveguide photodetector with a 3 dB-bandwidth of 1.33 GHz and a high-speed operation of 4.0 Gbps as well as high responsivity of ~0.3 A/W at 2 μm 19 .…”

Functional Mid‐Infrared Polaritonics in van der Waals Crystals

“…Graphene has been widely exploited to electronically modulate guided waves based on its tunable absorption and refractive index change, enabling broadband and ultrafast modulation . In particular, the tunable and ultrahigh‐confined properties of graphene plasmons discussed in Section allow dynamic manipulation of electromagnetic waves at deep‐subwavelength scale.…”

Optical Pre-Emphasis by Cascaded Graphene Electro Absorption Modulators

“…G RAPHENE is nowadays extensively studied for a large range of applications including its use in photonic integrated circuits (PICs) [1]. In PICs, graphene is expected to improve device performance simplifying, at the same time, the fabrication technology [2]. In particular, graphene-based photodetectors do not need Ge epitaxy (currently used for Si photonics photodetectors), and also work on much larger spectral regions.…”

“…They are capable of efficient and broadband electro-absorption or phase modulation and are compatible with complementary metal oxide semiconductor (CMOS) processing with simplified post-processing fabrication on various substrates. Indeed, graphene modulators do not strictly require Si or Ge doping, hence, Si, SiN, SiO 2 or other materials can be used as waveguides [2] and short devices (of Manuscript the order of 50-150 microns length), driven in lumped mode, can be realized.…”