Microcavity-Integrated Graphene Photodetector

Furchi, Marco M.; Urich, Alexander; Pospischil, Andreas; Lilley, Govinda; Unterrainer, K.; Detz, Hermann; Klang, P.; Andrews, A. M.; Schrenk, W.; Strasser, G.; Mueller, Thomas

doi:10.1021/nl204512x

Cited by 794 publications

(599 citation statements)

References 46 publications

(111 reference statements)

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“…However, the weak optical absorption of graphene 2,3 limits its photoresponsivity. To address this, graphene has been integrated into nanocavities 9 , microcavities 10 and plasmon resonators 11,12 , but these approaches restrict photodetection to narrow bands. Hybrid graphene-quantum dot architectures can greatly improve responsivity 13 , but at the cost of response speed.…”

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confidence: 99%

Chip-integrated ultrafast graphene photodetector with high responsivity

et al. 2013

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Graphene-based photodetectors have attracted strong interest for their exceptional physical properties, which include an ultrafast response 1-3 across a broad spectrum 4 , a strong electronelectron interaction 5 and photocarrier multiplication [6][7][8] . However, the weak optical absorption of graphene 2,3 limits its photoresponsivity. To address this, graphene has been integrated into nanocavities 9 , microcavities 10 and plasmon resonators 11,12 , but these approaches restrict photodetection to narrow bands. Hybrid graphene-quantum dot architectures can greatly improve responsivity 13 , but at the cost of response speed. Here, we demonstrate a waveguide-integrated graphene photodetector that simultaneously exhibits high responsivity, high speed and broad spectral bandwidth. Using a metal-doped graphene junction coupled evanescently to the waveguide, the detector achieves a photoresponsivity exceeding 0.1 A W 21 together with a nearly uniform response between 1,450 and 1,590 nm. Under zero-bias operation, we demonstrate response rates exceeding 20 GHz and an instrumentation-limited 12 Gbit s 21 optical data link.Graphene demonstrates ultrafast carrier dynamics for both electrons and holes, and it has been shown that a weak internal electric field allows high-speed and efficient photocarrier separation 2,3,14 . Moreover, graphene's two-dimensional nature appears to enable the generation of multiple electron-hole pairs for every highenergy photon excitation 6-8 . This carrier multiplication process is equivalent to inherent gain in graphene photodetection, which exists even without external bias, unlike traditional avalanche detection 15 . Despite these attractive features, the low optical absorption in graphene results in low photoresponsivity in vertical-incidence photodetector designs.Recently it has been revealed that coupling graphene to a bus waveguide can enhance light absorption over a broadband spectrum 16,17 . Here, we show that, by integrating a graphene photodetector onto a silicon-on-insulator (SOI) bus waveguide, it is possible to greatly enhance graphene absorption and the corresponding photodetection efficiency without sacrificing the high speed and broad spectral bandwidth. In our device, presented in Fig. 1a, a silicon waveguide is backfilled with SiO 2 and then planarized to provide a smooth surface for the deposition of graphene. A thin SiO 2 layer ( 10 nm) deposited on the planarized chip electrically isolates the graphene layer from the underlying silicon structures. The optical waveguide mode couples to the graphene layer through the evanescent field, leading to optical absorption and the generation of photocarriers. Two metal electrodes located on opposite sides of the waveguide collect the photocurrent. One of these electrodes is positioned 100 nm from the edge of the waveguide to create a lateral metal-doped junction that overlaps with the waveguide mode. The junction is close enough to the waveguide to efficiently separate the photoexcited electron-hole pairs at zero bias, but the meta...

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Chip-integrated ultrafast graphene photodetector with high responsivity

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“…However, the limited absorption in a single layer of graphene through inter-band transitions presents a key challenge 13 . Efforts to increase absorption include building microcavities around graphene 14,15 or enhancing the interaction with light through fabrication of quantum dots 16 , bowtie antennas 17 and other plasmonic nanostructures on top of the graphene [18][19][20] . Utilizing the Drude response of free electrons in combination with heavy chemical doping, an increased absorption reaching 40% in a single graphene layer has been achieved in the far-infrared 21 .…”

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Photocurrent in graphene harnessed by tunable intrinsic plasmons

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Graphene's optical properties in the infrared and terahertz can be tailored and enhanced by patterning graphene into periodic metamaterials with sub-wavelength feature sizes. Here we demonstrate polarization-sensitive and gate-tunable photodetection in graphene nanoribbon arrays. The long-lived hybrid plasmon-phonon modes utilized are coupled excitations of electron density oscillations and substrate (SiO 2 ) surface polar phonons. Their excitation by s-polarization leads to an in-resonance photocurrent, an order of magnitude larger than the photocurrent observed for p-polarization, which excites electron-hole pairs. The plasmonic detectors exhibit photo-induced temperature increases up to four times as large as comparable two-dimensional graphene detectors. Moreover, the photocurrent sign becomes polarization sensitive in the narrowest nanoribbon arrays owing to differences in decay channels for photoexcited hybrid plasmon-phonons and electrons. Our work provides a path to light-sensitive and frequency-selective photodetectors based on graphene's plasmonic excitations.

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“…To enhance the inherently weak light-matter interaction in this single atomic layer material, grahene has been coupled to optical waveguides and cavities [6,[10][11][12][13]. In the limit of wavelength-scale confinement, we recently demonstrated a dramatic enhancement of the light-matter interaction for graphene coupled to a planar photonic crystal (PPC) nanocavity, which reduced the cavity reflection by more than 20 dB [14].…”

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High-Contrast Electrooptic Modulation of a Photonic Crystal Nanocavity by Electrical Gating of Graphene

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We demonstrate a high-contrast electro-optic modulation of a photonic crystal nanocavity integrated with an electrically gated monolayer graphene. A high quality (Q) factor air-slot nanocavity design is employed for high overlap between the optical field and graphene sheet. Tuning of graphene's Fermi level up to 0.8 eV enables efficient control of its complex dielectric constant, which allows modulation of the cavity reflection in excess of 10 dB for a swing voltage of only 1.5 V. We also observe a controllable resonance wavelength shift close to 2 nm around a wavelength of 1570 nm and a Q factor modulation in excess of three. These observations allow cavity-enhanced measurements of the graphene complex dielectric constant under different chemical potentials, in agreement with a theoretical model of the graphene dielectric constant under gating. This graphene-based nanocavity modulation demonstrates the feasibility of high-contrast, low-power frequency-selective electro-optic nanocavity modulators in graphene-integrated silicon photonic chips.Graphene has intriguing optical properties and enables a range of promising optoelectronic devices [1][2][3][4][5][6][7][8][9]. To enhance the inherently weak light-matter interaction in this single atomic layer material, grahene has been coupled to optical waveguides and cavities [6,[10][11][12][13]. In the limit of wavelength-scale confinement, we recently demonstrated a dramatic enhancement of the light-matter interaction for graphene coupled to a planar photonic crystal (PPC) nanocavity, which reduced the cavity reflection by more than 20 dB [14]. Here, we employ this system to demonstrate a high contrast electro-optical modulation of the cavity reflection, in excess of 10 dB. The modulation is achieved by electrical gating of the graphene monolayer using an electrolyte, which, while slow, shows the fundamental capability arXiv:1211.0458v1 [physics.optics]

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Microcavity-Integrated Graphene Photodetector

Cited by 794 publications

References 46 publications

Chip-integrated ultrafast graphene photodetector with high responsivity

Chip-integrated ultrafast graphene photodetector with high responsivity

Photocurrent in graphene harnessed by tunable intrinsic plasmons

High-Contrast Electrooptic Modulation of a Photonic Crystal Nanocavity by Electrical Gating of Graphene

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