Experimental demonstration of mid-IR absorption enhancement in single layer CVD graphene

2020 ◽  
Vol 45 (14) ◽  
pp. 3861 ◽  
Author(s):  
Abedin Nematpour ◽  
Nicola Lisi ◽  
Rosa Chierchia ◽  
Maria Luisa Grilli
Keyword(s):  
Single Layer ◽  
Absorption Enhancement ◽  
Ir Absorption ◽  
Experimental Demonstration ◽  
Cvd Graphene

scholarly journals Towards Perfect Absorption of Single Layer CVD Graphene in an Optical Resonant Cavity: Challenges and Experimental Achievements

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 352
Author(s):  
Abedin Nematpour ◽  
Maria Luisa Grilli ◽  
Laura Lancellotti ◽  
Nicola Lisi
Keyword(s):  
Incident Angle ◽  
Resonant Cavity ◽  
Experimental Studies ◽  
Single Layer ◽  
Absorption Enhancement ◽  
Perfect Absorption ◽  
Cvd Graphene ◽  
Graphene Layers ◽  
Absorption Increase ◽  
Fabry Perot

Graphene is emerging as a promising material for the integration in the most common Si platform, capable to convey some of its unique properties to fabricate novel photonic and optoelectronic devices. For many real functions and devices however, graphene absorption is too low and must be enhanced. Among strategies, the use of an optical resonant cavity was recently proposed, and graphene absorption enhancement was demonstrated, both, by theoretical and experimental studies. This paper summarizes our recent progress in graphene absorption enhancement by means of Si/SiO2-based Fabry–Perot filters fabricated by radiofrequency sputtering. Simulations and experimental achievements carried out during more than two years of investigations are reported here, detailing the technical expedients that were necessary to increase the single layer CVD graphene absorption first to 39% and then up to 84%. Graphene absorption increased when an asymmetric Fabry–Perot filter was applied rather than a symmetric one, and a further absorption increase was obtained when graphene was embedded in a reflective rather than a transmissive Fabry–Perot filter. Moreover, the effect of the incident angle of the electromagnetic radiation and of the polarization of the light was investigated in the case of the optimized reflective Fabry–Perot filter. Experimental challenges and precautions to avoid evaporation or sputtering induced damage on the graphene layers are described as well, disclosing some experimental procedures that may help other researchers to embed graphene inside PVD grown materials with minimal alterations.

Plasmon-assisted interaction of Si with light, for cancer hyperthermia and electromagnetic energy harvest

2020 ◽  
Vol 92 (2) ◽  
pp. 20101
Author(s):  
Behnam Kheyraddini Mousavi ◽  
Morteza Rezaei Talarposhti ◽  
Farshid Karbassian ◽  
Arash Kheyraddini Mousavi
Keyword(s):  
Silicon Nanowires ◽  
Metallic Nanoparticles ◽  
Near Infrared ◽  
Optical Transition ◽  
Electromagnetic Energy ◽  
Energy Harvest ◽  
Absorption Enhancement ◽  
Ir Absorption ◽  
Absorption Mechanism ◽  
Near Ir

Metal-assisted chemical etching (MACE) is applied for fabrication of silicon nanowires (SiNWs). We have shown the effect of amorphous sheath of SiNWs by treating the nanowires with SF6 and the resulting reduction of absorption bandwidth, i.e. making SiNWs semi-transparent in near-infrared (IR). For the first time, by treating the fabricated SiNWs with copper containing HF∕H2O2∕H2O solution, we have generated crystalline nanowires with broader light absorption spectrum, up to λ = 1 μm. Both the absorption and photo-luminescence (PL) of the SiNWs are observed from visible to IR wavelengths. It is found that the SiNWs have PL at visible and near Infrared wavelengths, which may infer presence of mechanisms such as forbidden gap transitions other can involvement of plasmonic resonances. Non-radiative recombination of excitons is one of the reasons behind absorption of SiNWs. Also, on the dielectric metal interface, the absorption mechanism can be due to plasmonic dissipation or plasmon-assisted generation of excitons in the indirect band-gap material. Comparison between nanowires with and without metallic nanoparticles has revealed the effect of nanoparticles on absorption enhancement. The broader near IR absorption, paves the way for applications like hyperthermia of cancer while the optical transition in near IR also facilitates harvesting electromagnetic energy at a broad spectrum from visible to IR.

Interaction of single-layer CVD graphene with a metasurface of terahertz split-ring resonators

2013 ◽  
Author(s):  
Federico Valmorra ◽  
Giacomo Scalari ◽  
Curdin Maissen ◽  
Wangyang Fu ◽  
Christian Schönenberger ◽  
...  
Keyword(s):  
Single Layer ◽  
Ring Resonators ◽  
Split Ring ◽  
Split Ring Resonators ◽  
Cvd Graphene

scholarly journals Tunable mid IR absorption in single-layer, nanomeshed graphene

2019 ◽  
Vol 1253 ◽  
pp. 012023
Author(s):  
M Desouky ◽  
M A Swillam ◽  
A Kasry
Keyword(s):  
Single Layer ◽  
Ir Absorption

scholarly journals Polarization-Insensitive Waveguide Schottky Photodetectors Based on Mode Hybridization Effects in Asymmetric Plasmonic Waveguides

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6885
Author(s):  
Qian Li ◽  
Junjie Tu ◽  
Yang Tian ◽  
Yanli Zhao
Keyword(s):  
Integrated Circuits ◽  
High Speed ◽  
Large Scale ◽  
Layer Structure ◽  
Single Layer ◽  
Absorption Enhancement ◽  
Plasmonic Waveguides ◽  
Wavelength Band ◽  
Te Mode ◽  
Polarization Insensitive

Two types of configurations are theoretically proposed to achieve high responsivity polarization-insensitive waveguide Schottky photodetectors, i.e., a dual-layer structure for 1.55 µm and a single-layer structure for 2 µm wavelength band. Mode hybridization effects between quasi-TM modes and sab1 modes in plasmonic waveguides are first presented and further investigated under diverse metal types with different thicknesses in this work. By utilizing the mode hybridization effects between quasi-TE mode and aab0 mode, and also quasi-TM and sab1 mode in our proposed hybrid plasmonic waveguide, light absorption enhancement can be achieved under both TE and TM incidence within ultrathin and short metal stripes, thus resulting in a considerable responsivity for Si-based sub-bandgap photodetection. For 1.55 µm wavelength, the Au-6 nm-thick device can achieve absorptance of 99.6%/87.6% and responsivity of 138 mA·W−1/121.2 mA·W−1 under TE/TM incidence. Meanwhile, the Au-5 nm-thick device can achieve absorptance of 98.4%/90.2% and responsivity of 89 mA·W−1/81.7 mA·W−1 under TE/TM incidence in 2 µm wavelength band. The ultra-compact polarization-insensitive waveguide Schottky photodetectors may have promising applications in large scale all-Si photonic integrated circuits for high-speed optical communication.

Infrared Vision Using an Uncooled Thermo-Opto-Mechanical Camera: Design, Microfabrication, and Performance

1999 ◽  
Author(s):  
M. Mao ◽  
T. Perazzo ◽  
O. Kwon ◽  
Y. Zhao ◽  
A. Majumdar ◽  
...  
Keyword(s):  
Optical Design ◽  
Thermomechanical Analysis ◽  
Absorption Enhancement ◽  
Geometrical Shape ◽  
Ir Absorption ◽  
Residual Tensile Stress ◽  
Ir Radiation ◽  
Ir Camera ◽  
Optical Readout ◽  
And Performance

Abstract An uncooled infrared (IR) camera that is based on thermomechanical sensing and visible optical readout has been developed. The system contains a focal plane array (FPA) consisting of bimaterial cantilever beams made of silicon nitride (SiNx) and gold (Au) in each pixel. Absorption of incident IR radiation in the 8–14 μm wavelength range by SiNx in each cantilever beam raises its temperature, resulting in proportional deflection due to mismatch in thermal expansion of the two cantilever materials. To maximize the thermal performance, the conductance of each pixel was reduced to about five times of the radiation conductance. Based on thermomechanical analysis, the geometrical shape of the pixels were designed to maximize the cantilever sensitivity within the constraints of the pixel size and layout. Microfabrication of stress-balanced bimaterial cantilevers was achieved by varying the silicon concentration along the thickness of the SiNx films in order to balance the residual tensile stress in the Au film and the Cr adhesion layer between Au and SiNx. The optical design of each pixel was based on IR properties of the cantilever materials, IR absorption enhancement due to resonance cavity formation, as well as visible optics of deformable diffraction gratings. The latter formed the foundation for two different optical readout techniques that were both used for IR imaging. The results suggest that objects at temperatures as low as 30 °C can be imaged with the best noise-equivalent temperature difference (NETD) in the range of 2–5 K. It is estimated that further improvements that are currently being pursued can improve NETD to about 10 mK.

scholarly journals Graded metascreens to enable a new degree of nanoscale light management

2015 ◽  
Vol 373 (2049) ◽  
pp. 20140351 ◽  
Author(s):  
Nasim Mohammadi Estakhri ◽  
Christos Argyropoulos ◽  
Andrea Alù
Keyword(s):  
Electromagnetic Waves ◽  
Polarization State ◽  
Three Dimensional ◽  
Single Layer ◽  
Absorption Enhancement ◽  
Management Technique ◽  
Optical Waves ◽  
Novel Approach ◽  
Local Wave ◽  
Light Management

Optical metasurfaces, typically referred to as two-dimensional metamaterials, are arrays of engineered subwavelength inclusions suitably designed to tailor the light properties, including amplitude, phase and polarization state, over deeply subwavelength scales. By exploiting anomalous localized interactions of surface elements with optical waves, metasurfaces can go beyond the functionalities offered by conventional diffractive optical gratings. The innate simplicity of implementation and the distinct underlying physics of their wave–matter interaction distinguish metasurfaces from three-dimensional metamaterials and provide a valuable means of moulding optical waves in the desired manner. Here, we introduce a general approach based on the electromagnetic equivalence principle to develop and synthesize graded, non-periodic metasurfaces to generate arbitrarily prescribed distributions of electromagnetic waves. Graded metasurfaces are realized with a single layer of spatially modulated, electrically polarizable nanoparticles, tailoring the scattering response of the surface with nanoscale resolutions. We discuss promising applications based on the proposed local wave management technique, including the design of ultrathin optical carpet cloaks, alignment-free polarization beam splitters and a novel approach to enable broadband light absorption enhancement in thin-film solar cells. This concept opens up a practical route towards efficient planarized optical structures with potential impact on the integrated nanophotonic technology.

scholarly journals High-yield fabrication of nm-size gaps in monolayer CVD graphene

Nanoscale ◽  
2014 ◽  
Vol 6 (13) ◽  
pp. 7249-7254 ◽  
Author(s):  
Cornelia Nef ◽  
László Pósa ◽  
Péter Makk ◽  
Wangyang Fu ◽  
András Halbritter ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Single Layer ◽  
High Yield ◽  
Cvd Graphene

Herein we demonstrate the controlled and reproducible fabrication of sub-5 nm wide gaps in single-layer CVD graphene electrodes with an electroburning process and inferred the temperatures during the electroburning using Raman spectroscopy.

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