Search query: A graphene-based broadband  optical modulator

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abstract: Integrated optical modulators with high modulation speed, small footprint and large optical bandwidth are poised to be the enabling devices for on chip optical interconnects. Semiconductor modulators have therefore been heavily researched over the past few years. However, the device footprint of silicon based modulators is of the order of millimetres, owing to its weak electro optical properties. Germanium and compound semiconductors, on the other hand, face the major challenge of integration with existing silicon electronics and photonics platforms. Integrating silicon modulators with high quality factor optical resonators increases the modulation strength, but these devices suffer from intrinsic narrow bandwidth and require sophisticated optical design; they also have stringent fabrication requirements and limited temperature tolerances. Finding a complementary metal oxide semiconductor (CMOS) compatible material with adequate modulation speed and strength has therefore become a task of not only scientific interest, but also industrial importance. Here we experimentally demonstrate a broadband, high speed, waveguide integrated electroabsorption modulator based on monolayer graphene. By electrically tuning the Fermi level of the graphene sheet, we demonstrate modulation of the guided light at frequencies over 1 GHz, together with a broad operation spectrum that ranges from 1.35 to 1.6 um under ambient conditions. The high modulation efficiency of graphene results in an active device area of merely 25 um2, which is among the smallest to date. This graphene based optical modulation mechanism, with combined advantages of compact footprint, low operation voltage and ultrafast modulation speed across a broad range of wavelengths, can enable novel architectures for on chip optical communications.
author_names: Ming Liu

Xiaobo Yin

Erick Ulin-Avila

Baisong Geng

Thomas Zentgraf

Long Ju

Feng Wang

Xiang Zhang
title: A graphene based broadband optical modulator
venue: Nature
year: 2011

abstract: Abstract By exploiting the electroabsorption effect of graphene, we present a graphene based polarization insensitive optical modulator. The waveguide structure consists of a silica substrate, high index silicon strip waveguide, Si3N4 dielectric spacer, two graphene layers, and two metal electrodes. The modulator performance is comprehensively studied in terms of attenuation, insertion loss, modulation depth, and bandwidth. We achieve broadband >16 dB attenuation graphene based optical modulator over a 35 nm wavelength range (covering C band) with an imbalance of no >1 dB and insertion loss of <2 dB for transverse magnetic and transverse electric polarized modes. Moreover, the electrical properties such as energy per bit consumption (Ebit) are also studied.
author_names: Xiao Hu

Jian Wang
title: Design of graphene based polarization insensitive optical modulator
year: 2018

abstract: A graphene based plasmonic valley slot waveguide modulator has been presented, which consists of a layer of graphene Al2O3 graphene and two trapezoidal metal strips separated by valley slot region. Designed modulator has advantage of enhancement of mode confinement and provides an electro optic modulation with 'proper' (graphene's in plane) electric field of surface plasmons. The influences of geometric parameters and chemical potential of graphene on modulator performance have been investigated. By optimizing the geometric parameters, the designed modulator could achieve a 3 dB modulation depth only with 290 nm long waveguide and low energy consumption of 1 fj/bit. Also, this modulator can work over a broad wavelength range from 1400 to 1600 nm. These results indicate that proposed modulator could be applied as a high performance broadband optical modulator in photonic integrated circuits.
author_names: Mehdi Shirdel

Mohammad Ali Mansouri-Birjandi
title: A broadband graphene modulator based on plasmonic valley slot waveguide
year: 2019

abstract: Graphene is an excellent electronic and photonic material for developing electronic photonic integrated circuits in Si based semiconductor devices with ultra wide operational bandwidth. As an extended application, here we propose a broadband silicon optical modulator using a graphene integrated hybrid plasmonic waveguide, and investigate the optical characteristics numerically at a wavelength of 1.55 mm. The optical device is based on the surface plasmon polariton absorption of graphene. By electrically tuning the graphene's refractive index as low as that of a noble metal, the hybrid plasmonic waveguide supports a strongly confined highly lossy hybrid long range surface plasmon polariton strip mode, and hence light coupled from an input waveguide experiences significant power attenuation as it propagates along the waveguide. Over the entire C band from 1.530 to 1.565 mm wavelengths, the on/off extinction ratio is larger than 13.7 dB. This modulator has the potential to play a key role in realizing graphene Si waveguide based integrated photonic devices.
author_names: Jin-Soo Shin

Jin Tae Kim
title: Broadband silicon optical modulator using a graphene integrated hybrid plasmonic waveguide.
venue: Nanotechnology
year: 2015

abstract: We investigate a high efficiency broadband terahertz wave modulator with structures made from the conjugated polymer MEH PPV, graphene, and Si, irradiated with an external excitation laser. We demonstrate a strategy that can alleviate the tradeoffbetween the requirements of modulation depth and modulation speed in polymer/silicon terahertz wave modulators. Using terahertz time domain and continuous wave systems, we measured both the terahertz transmission modulation properties and the time responses of the modulator structures. The conjugated polymer/graphene/silicon structure achieved a high modulation factor of93% for transmission as well as improved the modulation speed of the devices based on polymer/silicon. The high modulation efficiency of the polymer/graphene/silicon structure was induced by the enhancement in carrier density and the extremely high carrier mobility of graphene, respectively.
author_names: Bo Zhang

Guocui Wang

Hongyu Ji

Bin Li

Jing-ling Shen
title: Graphene based Organic Optical Terahertz Modulator
venue: 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW THz)
year: 2018

abstract: We investigate a high efficiency broadband terahertz wave modulator with structures made from the conjugated polymer [2 methoxy 5 (2' ethylhexyloxy) 1, 4 phenylennevinylene] graphene, and Si, irradiated with an external excitation laser. We demonstrate a strategy that can alleviate the tradeoff between the requirements of modulation depth and modulation speed in polymer/silicon terahertz wave modulators. Using terahertz time domain and continuous wave systems, we measured both the terahertz transmission modulation properties and the time responses of the modulator structures. The conjugated polymer/graphene/silicon structure achieved a high modulation factor of 93% for transmission as well as improved the modulation speed of the devices based on polymer/silicon. The high modulation efficiency of the polymer/graphene/silicon structure was induced by the enhancement in carrier density and the extremely high carrier mobility of graphene, respectively.
author_names: Guocui Wang

Bo Zhang

Hongyu Ji

Xin Liu

Ting He

Longfeng Lv

Yanbing Hou

Jing-ling Shen
title: Monolayer graphene based organic optical terahertz modulator
year: 2017

abstract: We demonstrate a graphene based electro optic free space modulator yielding a reflectance contrast of 20% over a strikingly large 250nm wavelength range, centered in the near infrared telecom band. Our device is based on the original association of a planar Bragg reflector, topped with an electrically contacted double layer graphene capacitor structure employing a high work function oxide shown to confer a static doping to the graphene in the absence of an external bias, thereby reducing the switching voltage range to 1V. The device design, fabrication and opto electric characterization is presented, and its behavior modeled using a coupled optical electronic framework.
author_names: Thomas Wood

Jeremy Lhuillier

Malik Kemiche

Pierre Demongodin

Bertrand Vilquin

Pedro Rojo Romeo

Ali Belarouci

Lotfi Berguiga

Segolene Callard

Xavier Letartre

Christelle Monat
title: Low voltage, broadband graphene coated Bragg mirror electro optic modulator at telecom wavelengths.
venue: Optics express
year: 2020

abstract: Abstract In this article, a few layered graphene dielectric multilayer (metamaterial) electro optic modulator has been proposed in the mid and far infrared range that works on electro absorption mechanism. Graphene, both mono layer and few layer, is an actively tunable optical material that allows control of inter band and intra band transition by tuning its chemical potential. Utilizing this unique feature of graphene, we propose a multilayer graphene dielectric stack where few layer graphene is preferred over mono layer graphene. Although the total thickness of the stack still remains in the nanometer range, this device can exhibit superior performances in terms of (i) high modulation depth, (ii) ultra broadband performance, (iii) ultra low insertion loss due to inherent metamaterial properties, (iv)nano scale footprint, (v) polarization independence and (vi) capability of being integrated to a silicon waveguide. Interestingly, these superior performances, achievable by using few layer graphene with carefully designed metamaterial, may not be possible with mono layer graphene. Our proposals have been validated by both the effective medium theory and general transfer matrix method.
author_names: Ayed Al Sayem

Mahdy Rahman Chowdhury Mahdy

Ifat Jahangir

Md Saifur Rahman
title: Ultrathin ultra broadband electro absorption modulator based on few layer graphene based anisotropic metamaterial
year: 2015

abstract: Graphene based optical modulators have recently attracted much attention because of their characteristic ultrafast and broadband response. Their modulation depth (MD) and overall transmittance (OT) however, are often limited by optical loss arising from interband transitions. We report here an all optical, all fiber optical modulator with a Mach Zehnder interferometer structure that has significantly higher MD and OT than graphene based loss modulators. It is based on the idea of converting optically induced phase modulation in the graphene cladded arm of the interferometer to intensity modulation at the output of the interferometer. The device has the potential to be integrable into a photonic system in real applications.
author_names: Shaoliang Yu

Xiaoqin Wu

Keren Chen

Bigeng Chen

Xin Guo

Daoxin Dai

Limin Tong

Wei-Tao Liu

Y R Shen
title: All optical graphene modulator based on optical Kerr phase shift
year: 2016

abstract: Optical modulators are commonly used in communication and information technology to control intensity, phase, or polarization of light. Electro optic, electroabsorption, and acousto optic modulators based on semiconductors and compound semiconductors have been used to control the intensity of light. Because of gate tunable optical properties, graphene introduces new potentials for optical modulators. The operation wavelength of graphene based modulators, however, is limited to infrared wavelengths due to inefficient gating schemes. Here, we report a broadband optical modulator based on graphene supercapacitors formed by graphene electrodes and electrolyte medium. The transparent supercapacitor structure allows us to modulate optical transmission over a broad range of wavelengths from 450 nm to 2 mm under ambient conditions. We also provide various device geometries including multilayer graphene electrodes and reflection type device geometries that provide modulation of 35% The graphene supercapacitor structure together with the high modulation efficiency can enable various active devices ranging from plasmonics to optoelectronics.
author_names: Emre O Polat

Coskun Kocabas
title: Broadband optical modulators based on graphene supercapacitors.
venue: Nano letters
year: 2013