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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • energy distribution
  • graphene edge
  • vacuum transistor
  • Field emission
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Naval Research Laboratory
  • KeyW Corporation
  • Pohang University of Science and Technology (POSTECH)
1443 条数据
?? 中文（中国） ▾

  • Graphene-Incorporated Soft Capacitor for Mechanically-Adjustable Electro-Optic Modulators

    摘要： In addition to ultra-high capacity and speed in data management, future communication networks require enhanced performance via system reconfigurability under limited resources. Extremely high-speed operation renders optical data managing devices as excellent candidates to hybridize with current electronic devices; however, they still need tunability for system reconfiguration in an integrated scheme. We demonstrate an efficient electro-optic (EO) modulator that is mechanically tunable on a multiple optical waveguide system functioned with a soft capacitor structure incorporating graphene and poly(methyl methacrylate) (PMMA). The flexible capacitor that generates optical signals by temporal light absorption depending on electrical signals can be mechanically detached and re-attached from and onto a rigid surface of the waveguide. It provides either the on or off state of the modulating operation, and enables switching of the working waveguides following the reconfigured data routes. Quality-controlled graphene mainly provides the EO operation, and PMMA plays an important role as both the flexible dielectric layer in the capacitor and the passivation layer for graphene protection. The modulation effects of the manually prepared graphene-PMMA capacitor mechanically adjusted onto a side-polished optical fiber (D-shaped fiber) are investigated in terms of the extinction ratio (ER) of the transmitting light and the operational bandwidth. We successfully display an ER of the modulator up to 19.8 dB with a voltage control ranging from -50 V to 50 V. Its stable operation is verified with a modulation speed up to 2.5 MHz.

    关键词： electro-optic modulator,mechanical tuning,graphene,tunable modulator,soft material

    更新于2025-11-28 14:24:03

  • Carboxyl graphene oxide solution saturable absorber for femtosecond mode-locked erbium-doped fiber laser

    摘要： The carboxyl-functionalized graphene oxide (GO-COOH) is a kind of unique two-dimensional (2D) material and possesses excellent nonlinear saturable absorption property and high water-solubility. In this paper, we prepare saturable absorber (SA) device by depositing GO-COOH nanosheets aqueous solution on a D-shaped ?ber. The modulation depth (MD) and saturable intensity of the SA are measured to be 9.6% and 19 MW/cm2, respectively. By inserting the SA into the erbium-doped ?ber (EDF) laser, a passively mode-locked EDF laser has been achieved with the spectrum center wavelength of 1562.76 nm. The pulse duration, repetition rate, and the signal-to-noise ratio (SNR) are 500 fs, 14.79 MHz, and 80 dB, respectively. The maximum average output power is measured to be 3.85 mW. These results indicate that the GO-COOH nanosheets SA can be used as a promising mode locker for the generation of ultrashort pulses.

    关键词： nonlinear optical materials,mode-locked pulse,?ber lasers,carboxyl graphene oxide

    更新于2025-11-28 14:24:03

  • Graphene Heterostructure Integrated Optical Fiber Bragg Grating for Light Motion Tracking and Ultrabroadband Photodetection from 400 nm to 10.768 μm

    摘要： Integrated photonics and optoelectronics devices based on graphene and related 2D materials are at the core of the future industrial revolution, facilitating compact and flexible nanophotonic devices. Tracking and detecting the motion of broadband light in millimeter to nanometer scale is an unfold science which has not been fully explored. In this work, tracking and detecting the motion of light (millimeter precision) is first demonstrated by integrating graphene with an optical fiber Bragg grating device (graphene-FBG). When the incident light moves toward and away from the graphene-FBG device, the Bragg wavelength red-shifts and blue-shifts, indicating its light motion tracking ability. Such light tracking capability can be further extended to an ultrabroad wavelength range as all-optical photodetectors show the robust response from 400 nm to 10.768 μm with a linear optical response. Interestingly, it is found that graphene-Bi2Te3 heterostructure on FBG shows 87% higher photoresponse than graphene-FBG at both visible and telecom wavelengths, due to stronger phonon-electron coupling and photo-thermal conversion in the heterostructure. The device also shows superior stability even after 100 d. This work may open up amazing integrated nanophotonics applications such as astrophysics, optical communication, optical computing, optical logic gating, spectroscopy, and laser biology.

    关键词： 2D materials,graphene,ultrabroadband photodetection,heterostructures,optical fiber Bragg grating,light motion tracking

    更新于2025-11-28 14:24:03

  • Mode-locking in Er-doped fiber laser with reduced graphene oxide on a side-polished fiber as saturable absorber

    摘要： In this work, the generation of highly stable mode-locked pulses from a side-polished fiber (SPF) embedded with graphene oxide (rGO) nanoparticles (NPs) is proposed and demonstrated. The rGO NPs are obtained from a graphene oxide solution prepared using Hummer’s technique, before being reduced by a hydrothermal route. The rGO NPs, suspended in the form of a solution, are then drop-casted onto the SPF. The SPF is fabricated by polishing away the cladding layer of a single-mode fiber section, leaving the core exposed and allowing the evanescent field of the signal propagating through the fiber to interact directly with the NPs. The SPF is integrated into an erbium doped fiber laser (EDFL) cavity, and the strong nonlinear optical response and spectral filtering by the rGO NPs as well as total anomalous dispersion of the laser cavity generates highly stable soliton mode-locked pulses with visible Kelly’s sidebands at 1544.02 nm. The output pulses have a pulse repetition rate of 16.79 MHz and pulse duration of 1.17 ps throughout the mode-locking operation range of 64.44–280.5 mW. The rGO NP coated SPF in this work demonstrates the viability and performance of the SPF for mode-locked pulse generation via evanescent field interactions.

    关键词： Side polished fiber,Reduced graphene oxide,Mode-locked fiber laser,Saturable absorber

    更新于2025-11-28 14:23:57

  • Enhanced optical Kerr nonlinearity of graphene/Si hybrid waveguide

    摘要： In this work, we experimentally study the optical Kerr nonlinearities of graphene/Si hybrid waveguides with enhanced self-phase modulation. In the case of CMOS compatible materials for nonlinear optical signal processing, Si and silicon nitride waveguides have been extensively investigated over the past decade. However, Si waveguides exhibit strong two-photon absorption (TPA) at telecommunication wavelengths, which leads to a signi?cant reduction of the nonlinear ?gure-of-merit (FOM). In contrast, a silicon nitride based material system usually suppresses the TPA but simultaneously leads to the reduction of Kerr nonlinearity by one order of magnitude. Here, we introduce a graphene/Si hybrid waveguide, which maintains the optical properties and CMOS compatibility of Si waveguides, while enhancing the Kerr nonlinearity, by transferring over to the top of the waveguides. The graphene/Si waveguides are measured to have an enhanced nonlinear parameter of 510 W(cid:2)1 m(cid:2)1, compared with that of the Si waveguide of 150 W(cid:2)1 m(cid:2)1. An enhanced nonlinear FOM of 2.48 6 0.25 has been achieved, which is four times larger than that of the Si waveguide of 0.6 6 0.1. This work reveals the potential application of graphene/Si hybrid waveguides with high Kerr nonlinearity and FOM for nonlinear all-optical signal processing.

    关键词： nonlinear all-optical signal processing,graphene/Si hybrid waveguide,optical Kerr nonlinearity,CMOS compatible,self-phase modulation

    更新于2025-11-28 14:23:57

  • Opto-thermally Excited Fabry-Perot Resonance Frequency Behaviors of Clamped Circular Graphene Membrane

    摘要： An opto-thermally excited optical fiber Fabry-Perot (F-P) resonant probe with suspended clamped circular graphene diaphragm is presented in this paper. Then, the dependence of resonance frequency behaviors of graphene diaphragm upon opto-mechanical factors including membrane properties, laser excitation parameters and film boundary conditions are investigated via COMSOL Multiphysics simulation. The results show that the radius and thickness of membrane will linearly affect the optical fiber light-induced temperature distribution, thus resulting in rapidly decreasing resonance frequency changes with the radius-to-thickness ratio. Moreover, the prestress can be regulated in the range of 108 Pa to 109 Pa by altering the environmental temperature with a scale factor of 14.2 MPa/K. It is important to note that the availability of F-P resonant probe with a defective clamped circular graphene membrane can be improved notably by fabricating the defected circular membrane to a double-end clamped beam, which gives a broader perspective to characterize the resonance performance of opto-thermally excited F-P resonators.

    关键词： opto-thermal actuation,graphene membrane,Fabry-Perot resonator,resonance frequency simulation

    更新于2025-11-28 14:23:57

  • Graphene-Based Waist-Enlarged Optical Fibre Sensor for Measurement of Sucrose Concentration

    摘要： A novel sucrose sensor based on graphene-coated optical fibre with waist-enlarged bitapers as Mach-Zehnder interferometer is proposed and demonstrated. The sensor is formed by arc fusion splicing a photonic crystal fibre (PCF) sandwiched between two single-mode fibres (SMFs). The intermodal interference is achieved by two waist-enlarged fibre tapers at the coupling points between the PCF and two SMFs. The result shows that the dips of transmission spectra exhibit blue shift with the concentration increase of the sucrose, and the sensor has a high linear response (R2 = 0.98233) to sucrose with an excellent sensitivity of 3.36 pm/ppm in the range of 0–230 ppm. Additionally, the surface adsorption mechanism is also discussed. Such easily fabricated, cost-effective and small volume fibre interferometer could be used for sucrose sensing applications.

    关键词： Graphene,Sucrose Sensor,Blue Shift,Waist-Enlarged Bitapers,Mach-Zehnder Interferometer

    更新于2025-11-28 14:23:57

  • Laser transmission welding and surface modification of graphene film for flexible supercapacitor applications

    摘要： When a graphene ?lm is coated onto a ?exible polymer substrate, weak adhesion can cause delamination of the ?lm under mechanical bending. Moreover, as each graphene layer restacks, the performance of the ?lm as an electrode for a supercapacitor becomes limited. In this study, facile laser welding and surface modi?cation processes are demonstrated to overcome these limitations. First, a continuous wave laser beam is applied to the interface between the coated graphene and the underlying transparent polycarbonate substrate. This welding process signi?cantly improves their adhesion and enables excellent mechanical bendability. Second, surface modi?cation of graphene is achieved under ambient conditions by irradiating the graphene ?lm surface with a nanosecond pulsed laser. Sandwich-type supercapacitors are fabricated using these surface-modi?ed graphene electrodes with a PVA-H3PO4 electrolyte. The e?ect of the laser ?uence on the performance of the supercapacitor is investigated. At an optimal laser power, an areal capacitance of 4.7 mF/cm2 is achieved.

    关键词： Laser transmission welding,Graphene,Flexible device,Supercapacitor,Pulsed laser

    更新于2025-11-25 10:30:42

  • Graphene-Coated Glass Substrate for Continuous Wave Laser Desorption and Atmospheric Pressure Mass Spectrometric Imaging of Live Hippocampal Tissue

    摘要： Atmospheric pressure mass spectrometric (AP-MS) imaging technology combined with an inverted optical microscopic system is a powerful tool for determining the presence and spatial distributions of specific biomolecules of interest in live tissues. Efficient desorption and ionization are essential to acquire mass spectrometric (MS) information in an ambient environment. In this study, we demonstrate a new and efficient desorption process using a graphene-coated glass substrate and a continuous wave (CW) laser for high-resolution AP-MS imaging of live hippocampal tissue. We found that desorption of biomolecules in a live tissue slice was possible with the aid of a graphene-coated glass substrate and indirect application of a 532 nm CW-laser on the graphene substrate. Interestingly, the desorption efficiency of live tissue on the graphene-coated substrate was strongly dependent on the number of graphene layers. Single-layer graphene was found to be the most sensitive substrate for efficient desorption and reproducible high-resolution hippocampal tissue imaging applications. The subsequent ionization process using nonthermal plasma generated sufficient amounts of molecular ions to obtain high-resolution 2-dimensional MS images of the cornu ammonis (CA) and the dentate gyrus (DG) regions of the hippocampus. Therefore, graphene-coated substrates could be a promising platform to induce an efficient desorption process essential for highly reproducible ambient MS imaging.

    关键词： Hippocampal tissue,Mass spectrometry imaging,Laser desorption,Graphene-coated substrate,Ambient mass spectrometry

    更新于2025-11-25 10:30:42

  • Graphene quantum dot based charge-reversal nanomaterial for nucleus-targeted drug delivery and efficiency controllable photodynamic therapy

    摘要： Graphene quantum dots (GQD), the new zero-dimensional carbon nanomaterial, has been demonstrated as a promising material for biomedical applications due to its good biocompatibility and low toxicity. However, the integration of multiple therapeutic approaches into a nano-sized platform based on the GQD has not been explored yet to our best knowledge. In this report, we regulate the generation of reactive oxygen species (ROS) when using the GQD as a photosensitizer by varying the doping amount of nitrogen atoms to achieve efficiency controllable photodynamic therapy (PDT). On the other hand, charge-reversal (3-Aminopropyl) triethoxysilane (APTES) was employed to conjugate on the surface of GQD for nucleus targeting drug delivery for the first time. The treatment outcome of produced ROS and nucleus-targeting drug delivery was investigated by fluorescence imaging. The results demonstrated that the N-GQD-DOX-APTES in dual roles as a drug carrier and photosensitizer could achieve nucleus-targeting delivery and strong ROS production simultaneously. This approach provides a promising strategy for the development of multifunctional therapy in one nano platform for biomedical applications.

    关键词： nucleus-targeted drug delivery,Graphene quantum dots,nitrogen doped graphene quantum dots,charge-reversal,photodynamic therapy

    更新于2025-11-21 11:24:58