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MoSe_(2)/WS_(2) heterojunction photodiode integrated with a silicon nitride waveguide for near infrared light detection with high responsivity

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Light(Science & Applications) 2023年第3期12卷 456-464页

作者： Rivka Gherabli S.R.K.C.Indukuri Roy Zektzer Christian Frydendahl Uriel Levy department of applied physics The Faculty of ScienceThe Center for Nanoscience and NanotechnologyThe Hebrew University of JerusalemJerusalem91904Israel

We demonstrate experimentally the realization and the characterization of a chip-scale integrated photodetector for the near-infrared spectral regime based on the integration of a MoSe_(2)/WS_(2) heterojunction on top of a silicon nitride *** configuration achieves high responsivity of~1 A W−1 at the wavelength of 780 nm(indicating an internal gain mechanism)while suppressing the dark current to the level of~50 pA,much lower as compared to a reference sample of just MoSe_(2) without WS_(2).We have measured the power spectral density of the dark current to be as low as~1×10^(−12) A Hz−0.5,from which we extract the noise equivalent power(NEP)to be~1×10^(−12) W Hz^(−0.5).To demonstrate the usefulness of the device,we use it for the characterization of the transfer function of a microring resonator that is integrated on the same chip as the *** ability to integrate local photodetectors on a chip and to operate such devices with high performance at the near-infrared regime is expected to play a critical role in future integrated devices in the field of optical communications,quantum photonics,biochemical sensing,and more.

关键词： heterojunction waveguide resonator

Synthesis and characterization of highly-ordered barium-strontium titanate nanotube arrays fabricated by sol-gel method

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Chinese physics B 2009年第9期18卷 3922-3927页

作者：陈煜程伟郭峰李美亚刘威赵兴中 department of physics Wuhan University nanoscience and nanotechnology center Wuhan University

Highly uniformed barium-strontium titanate nanotube arrays were fabricated using a porous anodic aluminum oxide template from a barium-strontium titanate sol-gel solution. Electron microscope results showed that nanotubes with uniform length and diameter were obtained. The diameters and lengths of these nanotubes were dependent on the pore diameter and the thickness of the applied anodic aluminum oxide template. High resolution transmission electron microscopy and the selected-area electron diffraction pattern investigations demonstrated the perovskite structure and the polycrystalline of the fabricated barium-strontium titanate nanotubes. The characterization of the electrical and dielectric properties had also been made. Compared to thin film material, the intrinsic leakage current density is almost the same. Besides, at 30 ℃ the dielectric constant and dielectric loss of the fabricated nanotube is 80 and 0.027 at 1 MHz respectively.

关键词： nanotubes barium-strontium titanate sol-gel

High-order plasmon resonances in an Ag/Al_2O_3 core/shell nanorice

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Chinese physics B 2014年第2期23卷 19-24页

作者：陈立魏红陈克求徐红星 department of applied physics Hunan University Beijing National Laboratory for Condensed Matter physics and Institute of physics Chinese Academy of Sciences center for nanoscience and nanotechnology and School of Physics and TechnologyWuhan University

Using numerical simulation, we investigate the high-order plasmon resonances in individual nanostructures of an Ag nanorice core surrounded by an Al2O3 shell. The peak positions of localized surface plasmon resonances （LSPRs） are red-shifted exponentially with the increase of the dielectric shell thickness. This is due to the exponential decay of electromagnetic field intensity in the direction perpendicular to the interface. This exponential red-shift depends on the wavelength of the resonance peak instead of the resonance order. In addition, we find that the LSPRs in an Ag nanorice of 60-nm width can be perfectly described by a single linear function. These features make nanorice an ideal platform for sensing applications.

关键词： localized surface plasmon resonances nanorice core-shell LSPR sensing

Modulational instability of optically induced nematicon propagation

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Chinese physics B 2013年第12期22卷 578-588页

作者： L. Kavitha M. Venkatesh S. Dhamayanthi D. Gopi department of physics Periyar University The Abdus Salam International center for Theoretical physics center for nanoscience and nanotechnology Periyar University department of Chemistry Periyar University

We report the modulational instability （MI） analysis for the modulation equations governing the propagation of coherent polarized light through a nematic liquid crystal （NLC） slab, in the limit of low light intensity and local material response. The linear stability analysis of the nonlinear plane wave solutions is performed by considering both the wave vectors （k,l） of the basic states and wave vectors （K,L） of the perturbations as free parameters. We compute the MI gain, and the MI gain peak is reduced and the stable bandwidth is widened with the increase of the strength of the applied electric field. Further, we invoke the extended homogeneous balance method and Exp-function method aided with symbolic computation and obtain a series of periodic solitonic humps of nematicon profiles admitting the propagation of laser light in the NLC medium.

关键词： solitons computational methods liquid crystals nonlinearity

Selective nano-buckling improves the performance of graphene logic transistors

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National Science Review 2024年第2期11卷 95-96页

作者： Tong Yang Ming Yang department of applied physics The Hong Kong Polytechnic University Research Centre for nanoscience and nanotechnology The Hong Kong Polytechnic University

The massive integration of silicon-based transistors into modern electronic devices greatly increases power consumption and heat generation/dissipation[1]. In this concern, transistors based on atomically-thin graphene that exhibit high electric and thermoelectric conductivities with negligible contact resistance,

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A Sign Alternation of Nonlinear Absorption in Gold Composite Films in Z-Scan

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Chinese physics Letters 2005年第9期22卷 2286-2289页

作者：陈代坚丁沙韩俊波周慧君肖思熊贵光王取泉 department of physics Wuhan University Wuhan 430072 center of nanoscience and nanotechnology Research Wuhan University Wuhan 430072

Au-TiO2 composite films with Au atom content varying from about 15% to 82% are prepared by co-sputtering technique. Both open- and closed-aperture Z-scan of the samples are performed in the femtosecond time region. A conversion of the nonlinear absorption from negative to positive is observed as the A u atom content increases due to the saturation of reverse saturable absorption. The nonlinear refractive index γ and effective nonlinear absorption coefficient βeff at the Au atom content of 54% are measured to be 1.6 × 10^-2 cm^2/GW and -2.6 ×10^3 cm/GW, respectively. The corresponding third-order optical nonlinearity X^（3） is about 6.3 × 10^-8 esu.

关键词： 3RD-ORDER OPTICAL NONLINEARITY THIN-FILMS SINGLE-BEAM THRESHOLD POLYMER SILVER

Electrochemically Assisted Photocatalytic Oxidation of Methanol on TiO_2 Nanotube Arrays

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Journal of Materials Science & Technology 2010年第6期26卷 535-541页

作者： R.Mohammadpour A.Iraji zad N.Taghavinia M.Rahman M.M.Ahadian Institute for nanoscience and nanotechnology Sharif University of Technology department of physics Sharif University of Technology

The influence of an externally applied bias on photocatalytic performance of crystallized TiO2/Ti nanotubular electrode formed by anodization in fluoride-based electrolyte were investigated and compared to the behavior of multiporous TiO2 electrode. The photoelectrocatalytic oxidation behavior of methanol over the nanotubular electrode has been studied by measuring photocurrent response, potentiodynamic polarization spectroscopy and using electrochemical impedance spectroscopy （EIS）. It was found that the photoelectrocatalytic oxida- tion and the charge transfer rate constant of reaction on TiO2/Ti nanotubular electrode can significantly be increased by applying electrochemical bias. Moreover, TiO2 electrodes have considerably better performance alytic performance. based on the results, it was found that the nanotubular in comparison with porous samples in photoelectrocatalytic performance.

关键词： TiO2 nanotube Photoelectrocatalyst Electrochemical impedance spectroscopy Methanol

Propagation of an electromagnetic soliton in an anisotropic biquadratic ferromagnetic medium

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Chinese physics B 2013年第3期22卷 275-281页

作者： L.Kavitha M.Saravanan D.Gopi department of physics Periyar University The Abdus Salam International Centre for Theoretical physics TriesteItaly center for nanoscience and nanotechnology Periyar University department of Chemistry Periyar University

Information storage technology based on anisotropic ferromagnets with sufficiently high magneto-optical effects has received much attention in recent ***-optical recording combines the merits of magnetic and optical *** investigate the magneto-optical effects on a biquadratic ferromagnet and show that the dynamics of the system are governed by a perturbed nonlinear Schro¨dinger *** evolutions of amplitude and velocity of the soliton are found to be time independent,thereby admitting the lossless propagation of the electromagnetic soliton in the medium,which may have potential applications in soliton based optical communication *** also exploit the role of perturbation,which has a significant impact on the propagation of an electromagnetic soliton.

关键词： solitons classical spin models Maxwell equations nonlinear dynamics

Efect of Varying Dzyaloshinskii–Moriya Interaction on the Bistable Nano-Scale Soliton Switching

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Communications in Theoretical physics 2013年第12期60卷 658-662页

作者： L.Kavitha M.Saravanan V.Senthilkumar D.Gopi department of physics Periyar University The Abdus Salam International Centre for Theoretical physics center for nanoscience and nanotechnology Periyar University department of Chemistry Periyar University

The effect of Dzyaloshinskii-Moriya （D-M） interaction on the bistable nano-scale soliton switching offers the possiblity of developing a new innovative approach for data storage technology. The dynamics of Heisenberg ferromagnetic spin system is expressed in terms of generalized inhomogeneous higher order nonlinear Schr6dinger （NLS） equation. The bistable soliton switching in the ferromagnetic medium is established by solving the associated coupled evolution equations for amplitude and velocity of the soliton using the fourth order Runge-Kutta method numerically.

关键词： solitons magnetization reversal mechanisms perturbation theory exchange interactions