Ultra-compact integrated graphene plasmonic photodetector with bandwidth above 110 GHz

Abstract

Graphene-based photodetectors, taking the advantages of high carrier mobility and broadband absorption in graphene, have recently experienced rapid development. However, their performance with respect to responsivity and bandwidth is still limited by weak light-graphene interaction and large resistance-capacitance product. Here, we demonstrate a waveguide coupled integrated graphene plasmonic photodetector on a silicon-on-insulator platform. Benefiting from plasmonic enhanced graphene-light interaction and subwavelength confinement of the optical energy, we achieve a small-footprint grapheneplasmonic photodetector working at the telecommunication window, with large bandwidth beyond 110 GHz and high intrinsic responsivity of 360 mA/W. Attributed to the unique electronic bandstructure of graphene and its ultra-broadband absorption, operational wavelength range extending beyond mid-infrared, and possibly further, can be anticipated. Our results show that the combination of graphene with plasmonic devices has great potential to realize ultra-compact and high-speed optoelectronic devices for graphene-based optical interconnects. arXiv:1808.04815v3 [physics.app-ph]

Ultrafast Plasmonic Graphene Photodetector Based on the Channel Photothermoelectric Effect

“…To find an answer to the questions raised above, we first need to classify the main effects that can contribute to photocurrent (or photovoltage) generation in waveguide-integrated graphene devices [25][26][27][28]. One can distinguish three main effects -photo-voltaic (PV) [29][30][31][32][33][34], photo-bolometric (PB) [35][36][37][38][39] and photo-thermoelectric (PTE) [40][41][42][43] effects. The choice of the effect depends on device configuration, design and operation conditions [25,28,34,40].…”

“…In practice this means that the in-plane component of the electric field in graphene should be strong but also decay very fast from one electrode to another. Taking into account those aspects, we proposed here a photodetector that is based on the metal-graphene-metal (MGM) arrangement [29,30,43] with a graphene channel contacted by two electrodes, either of the same [30] or two different metals [29,34]. The difference in work function between the metal pads and graphene leads to charge transfer with a consequent shift of the graphene's Fermi level that is in contact with the metal [29,34,56].…”

“…Furthermore, a doping of graphene can be realized by injection of nonequilibrium hot electrons generated from the plasmonic structures into a nearby graphene structure [65]. The transit-time-limited bandwidth of the photodetector is given by [14,29]:…”

Strong Light–Matter Interactions Enabled by Polaritons in Atomically Thin Materials

“…Recent developments in vdW integration of 2D materials present alternative ways to create vdW heterostructures with unique and desirable electronic and optical properties that are unavailable in isolated 2D materials . All of these advances have triggered fundamental explorations of newly developed 2D and vdW heterostructures, stimulating investigation of their potential applications in energy harvesting, photonics and optoelectronics, and biomedical technologies …”

“…[7,8] Recent developments in vdW integration of 2D materials present alternative ways to create vdW heterostructures with unique and desirable electronic and optical properties that are unavailable in isolated 2D materials. [9,10] All of these advances have triggered fundamental explorations of newly developed 2D and vdW heterostructures, stimulating investigation of their potential applications in energy harvesting, [11][12][13][14] photonics and optoelectronics, [15][16][17][18][19][20][21][22] and biomedical technologies. [23][24][25][26][27][28] Due to their atomic-scale thickness, light-matter interactions in 2D materials are often weak; for this reason, the strong light-matter interactions in 2D and vdW heterostructures that have been observed are often fueled by polaritonic excitations.…”