Light-induced switching of a chalcogenide-coated side-polished fiber device

Wen, Shu-Chen; Chang, Chir-Weei; Lin, Chia-Ming; Liu, Hua-an; Hsiao, Vincent K. S.; Yu, Jianhui; Chen, Zhe

doi:10.1016/j.optcom.2014.08.033

Cited by 11 publications

(4 citation statements)

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“…We thus anticipate that these systems will be able to modulate vis–NIR light at high speeds with a minute consumption of power, typical of capacitive devices. This is an advantage with respect to alternative commutation devices based on quantum wells and phase-change materials . For example, we envision an integrated commutation device operating over an area A = 50 × 50 μm 2 (i.e., covering a customary optical beam size), for which we estimate a capacitance C = Aϵ/4π d ≈ 0.3 pF, where we consider ϵ = 4 (dc silica) and a gate separation d = 300 nm (notice that there is great flexibility in the choice of d in some of our devices).…”

Section: Discussionmentioning

confidence: 99%

“…This is an advantage with respect to alternative commutation devices based on quantum wells 47 and phase-change materials. 48 For example, we envision an integrated commutation device operating over an area A = 50 × 50 μm 2 (i.e., covering a customary optical beam size), for which we estimate a capacitance C = Aϵ/4πd ≈ 0.3 pF, where we consider ϵ = 4 (dc silica) and a gate separation d = 300 nm (notice that there is great flexibility in the choice of d in some of our devices). The time response is then limited by the sheet resistance of the graphene layer (∼100 Ω/□), giving an overall cutoff frequency for the electrical bandwidth of 1/2πRC ≈ 5 GHz, while the optical limit for the electrical modulation of the photonic response (i.e., the effect related to the decay time of the resonance) renders a larger cutoff (c/2LQ ≈ 150 GHz for a cavity length L ≈ 1 μm and a quality factor Q ≈ 10 3 ).…”

Section: ■ Conclusion and Outlookmentioning

confidence: 99%

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Resonant Visible Light Modulation with Graphene

Pruneri

Abajo

2015

ACS Photonics

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Fast modulation and switching of light at visible and near-infrared (vis–NIR) frequencies are of utmost importance for optical signal processing and sensing technologies. No fundamental limit appears to prevent us from designing wavelength-sized devices capable of controlling the light phase and intensity at gigahertz (and even terahertz) speeds in those spectral ranges. However, this problem remains largely unsolved, despite recent advances in the use of quantum wells and phase-change materials for that purpose. Here, we explore an alternative solution based upon the remarkable electro-optical properties of graphene. In particular, we predict unity-order changes in the transmission and absorption of vis–NIR light produced upon electrical doping of graphene sheets coupled to realistically engineered optical cavities. The light intensity is enhanced at the graphene plane and so is its absorption, which can be switched and modulated via Pauli blocking through varying the level of doping. Specifically, we explore dielectric planar cavities operating under either tunneling or Fabry–Perot resonant transmission conditions, as well as Mie modes in silicon nanospheres and lattice resonances in metal particle arrays. Our simulations reveal absolute variations in transmission exceeding 90% as well as an extinction ratio of >15 dB with small insertion losses using feasible material parameters, thus supporting the application of graphene in fast electro-optics at vis–NIR frequencies.Peer ReviewedPostprint (author’s final draft

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Section: Discussionmentioning

confidence: 99%

Section: ■ Conclusion and Outlookmentioning

confidence: 99%

Resonant Visible Light Modulation with Graphene

Pruneri

Abajo

2015

ACS Photonics

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“…Although the exact mechanism of photostriction observed in GeS is not implicit, an interplay between transient photodarkening (red shift of the optical absorption edge by illumination) and photoinduced volume expansion has been suggested to cause the photostriction effect. [6,17,[23][24][25][26] The photodarkening phenomenon mainly occurs in GeS film due to increase in the number of wrong bonds such as S-S [434 nm peak in Raman spectra shown in Figure 2(d)]. [2,4] And the characteristic behavior (i.e., τ rise > τ fall ) observed in GeS could be correlated with the temporal influence of the ambient oxygen pressure on the surface of the coated GeS film during illumination.…”

Section: Resultsmentioning

confidence: 99%

In situ monitoring of photostriction in chalcogenide glass film using fiber Bragg grating sensors

Sivakumar

Varma

Singh

et al. 2017

International Journal of Optomechatronics

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The reversible photostriction (photomechanical strain) in Ge 35 S 65 chalcogenide thin film deposited by a solvent casting method has been monitored using a fiber Bragg grating (FBG) sensor. The shift in Bragg wavelength is used as a probing parameter to quantitatively measure the photoinduced strain arising because of structural modifications in these films under illumination. Exposure to band gap light (405 nm) and above band gap light (302 and 254 nm) leads to a reversible photostriction effect of the order of 100 µε. The present study shows that FBG sensors can be used to effectively measure the optomechanical actuation in chalcogenide films caused by the reversible photostriction effect in the visible and ultraviolet wavelength region.

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“…This is an advantage with respect to alternative commutation devices based on quantum-wells [119] and phase-change materials. [120] The large electro-optical response of graphene combined with its small volume is thus ideal attributes for the design of fast optical modulators and switches operating in the vis-NIR, which can benefit from the coupling to optical resonators such as those explored in this chapter. These findings open a new avenue for the development of compact electro-optical components such as tunable light filters, switches, and sensors in the vis-NIR spectral region, that are appealing for micro integration and mass production.…”

Section: Discussionmentioning

confidence: 99%

Toward next-generation nanophotonic devices

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In this thesis, we aim to explore several novel designs of nanostructures based on graphene to realize various functionalities. We briefly introduce the fundamental concepts and theoretical models used in this thesis in Chapter 1. Following the macroscopic analytical method outlined in the first chapter, in Chapter 2 we show that simple simulation methods allow us to accurately describe the optical response of plasmonic nanoparticles, including retardation effects, without the requirement of large computational resources. We then move to our proposed first type of device: optical modulators. We explore graphene sheets coupled to different kinds of optical resonators to enhance the light intensity at the graphene plane, and so also its absorption, which can be switched on/off and modulated through varying the level of doping, as explored in Chapter 3. Unity-order changes in the transmission and absorption of incident light are predicted upon electrical doping of graphene. Heat deposition via light absorption can severely degrade the performance and limit the lifetime of nano-devices (e.g., aforementioned optical modulators), which makes the manipulation of nanoscale heat sources/flows become crucial. In Chapter 4, we exploit the extraordinary optical and thermal properties of graphene to show that ultrafast radiative heat transfer can take place between neighboring nanostructures facilitated by graphene plasmons, where photothermally induced effects on graphene plasmons are taken into account. Our findings reveal a new regime for the nanoscale thermal management, in which non-contact heat transfer becomes a leading mechanism of heat dissipation. Apart from the damage caused by heat deposition, generated thermal energy can be in fact used as a tool for photodetection (e.g., silicon bolometers for infrared photodetection). In Chapter 5, we show that the excitation of a single plasmon in a graphene nanojunction produces profound modifications in its electrical properties through optical heating, which we then use to demonstrate an efficient mid-infrared photodetector working at room temperature based on theoretical predictions that are corroborated in an experimental collaboration with the group of Prof. Fengnian Xia in Yale University. Finally, in Chapter 6, we show through microscopic quantum-mechanical simulations, introduced in the first chapter, that both the linear and nonlinear optical responses of graphene nanostructures can be dramatically altered by the presence of a single neighboring molecule that carries either an elementary charge or a small permanent dipole. Based on these results, we claim that nanographenes can serve as an efficient platform for detecting charge- or dipole-carrying molecules. En esta tesis, pretendemos explorar varios diseños novedosos de nanoestructuras basadas en grafeno, con diversas funcionalidades. Tras presentar brevemente los conceptos fundamentales y los modelos teóricos utilizados en esta tesis en el Capítulo 1, en el Capítulo 2 mostramos la posibilidad de describir la respuesta de nanopartículas plasmónicas (incluyendo efectos de retardo) mediante métodos de simulación semi-analíticos sencillos y sin la necesidad de emplear grandes recursos computacionales. Posteriormente, empleamos estos modelos en el desarrollo de un primer tipo de dispositivo: moduladores ópticos. Añadiendo láminas de grafeno acopladas a diferentes tipos de resonadores ópticos, podemos mejorar la intensidad de la luz en el plano del grafeno, y por lo tanto también su nivel de absorción, la cual puede ser modulada a voluntad mediante el nivel de dopado electrostático del grafeno, como se explora en el Capítulo 3. Los modelos empleados predicen cambios en la transmisión del orden de la unidad, produciendo así la absorción total por parte del dispositivo de la luz incidente. En esta clase de dispositivos, así como en todos los dispositivos nanofotónicos, la producción de calor mediante la absorción de la luz puede degradar severamente su rendimiento, así como limitar su vida útil, lo que hace que la manipulación de la fuente y el flujo de calor en la nanoescala sea una componente crucial del desarrollo. En el Capítulo 4, empleamos las extraordinarias propiedades ópticas y térmicas del grafeno para mostrar que puede tener lugar una transferencia ultrarrápida de calor radiativo entre nanoestructuras vecinas, facilitada por los plasmones del grafeno, los cuales a su vez experimentan efectos fototérmicos asociados con este proceso de disipación. Nuestros hallazgos revelan un nuevo régimen para la energía térmica a nanoescala, en la que la transferencia de calor radiativa se convierte en el mecanismo principal de disipación de calor. Además de los daños causados por la deposición de calor, la energía térmica generada puede ser de hecho usada como herramienta para la fotodetección: tal es el caso, por ejemplo, de los bolómetros de silicona, empleados para la fotodetección por infrarrojos. En el Capítulo 5, mostramos que la excitación de un solo plasmón en una unión de grafeno altera radicalmente sus propiedades eléctricas debido al calentamiento óptico. Este hecho puede ser empleado para demostrar el funcionamiento eficaz de un fotodetector en la región media de los infrarrojos a temperatura ambiente, tanto a través de predicciones teóricas como su corroboración experimental (en colaboración con el grupo del Prof. Fengnian Xia de la Universidad de Yale). Finalmente, en el Capítulo 6, mostramos a través de simulaciones mecánico-cuánticas (introducidas en el Capítulo 1), que tanto la respuesta óptica lineal como la no lineal de las nanoestructuras de grafeno pueden ser dramáticamente alteradas por la presencia de una sola molécula vecina que transporte o bien una carga elemental o un dipolo permanente. En base a estos resultados, afirmamos que las estructuras de grafeno nanoscópicas podrían ser una plataforma eficiente para detectar moléculas portadoras de carga o dipolos.

show abstract

Light-induced switching of a chalcogenide-coated side-polished fiber device

Cited by 11 publications

References 20 publications

Resonant Visible Light Modulation with Graphene

Resonant Visible Light Modulation with Graphene

In situ monitoring of photostriction in chalcogenide glass film using fiber Bragg grating sensors

Toward next-generation nanophotonic devices

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