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A graphene reflectarray is designed to realize two functions simultaneously at terahertz frequency: generating vortex waves, and steering the waves. Four parts of graphene patches with different values of reflection phase are used to generate vortex waves. On the other hand, generalized Snell's Law is applied to introduce additional reflection phase. Anomalous reflection is realized to steer the Vortex...
We propose an optical gas sensor using anodic aluminum oxide (AAO) and a graphene oxide (GO) layer to detect hydrophilic gas. In the proposed sensor, GO reacts with the induced gas to cause a change in the refractive index of the AAO surface, which can be optically detected by measuring the reflected wave on the surface of the device. By using the high reactivity of GO to hydrophilic gases owing to...
We have demonstrated a new composite thin film for encapsulation consisting of polydimethylsiloxane (PDMS) and graphene. Graphene is a kind of hydrophobic material, causing that moisture could hardly penetrate into the surface of graphene. Graphene is usually fabricated by the method of Chemical Vapor Deposition (CVD). The atomic distance of graphene is very small; thus the water vapor channel from...
We demonstrate a new fiber-optic current sensor based on graphene nanoelectromechanical systems (NEMS) with a graphene membrane covering the hole on a fiber tip and two gold electrodes on opposite sides of the tip. The suspended graphene membrane will deform due to thermal effect when electrical current flows through it. Then the strain in the graphene nanomechanical resonator will change and it leads...
Field electron emission patterns emitted from few-layer graphene with different edge morphology were investigated using field emission microscopy (FEM). The FEM image of few-layer graphene was observed as a “lantern”, which is composed of light and dark fringes. The relationship between graphene edge morphology and field emission pattern was investigated using a emission electron spatial interference...
The MoS2/Graphene heterojunction prepared through a facile hydrothermal method is used as an optical modulator to realize 2.8 μm passively Q-switched solid state pulse laser for the first time as far as we know. This work certifies that the two-dimensional material heterojunction is a kind of outstanding mid-infrared modulators.
A microfluidic flowmeter is proposed based on graphene integrated “hot-wire” structure. A long-period fiber grating (LPFG) is written in a single mode fiber by CO2 laser to excite the higher-order mode. Graphene is coated around the grating to absorb the higher-order mode and generate the heat. The fiber is sealed into a home-made tube. When the microfluid flows through the graphene, the heat is taken...
A high-speed traveling wave electro-absorption modulator based on grapheme-micro fiber is designed. Graphene modulates the optical transmission intensity by changing its fermi level under different applied voltages. Graphene has an extremely high carrier mobility which has a potential electrical bandwidth of 500 GHz. However, the bandwidth of the state-of-art graphene based modulator is limited by...
Graphene is an appealing material due to its distinct electronic, mechanical and optical properties. Recently, graphene based field effect transistor (GFET) have been rapidly developed and show the potential applications.
Active modulation of light with large optical bandwidths (∼100 nm [1]) is required in photonic devices, such as modulators for fiber communications [1] and saturable absorbers for ultrafast pulse generation [2,3]. Present modulators use expensive materials, (e.g. LiNbO3 [4], III-V semiconductors [5], and Ge on silicon-on-insulator (SOI) [6]), and are limited by narrowband operation (∼20 nm for quantum-confined...
Recently, graphene has attracted wide attentions for its unique properties in optics and electronics. Many excellent designs were proposed base on the structured graphene such as modulators, optical polarizers and limiters [1]. Thus, the fabrication ability of graphene structures can be thought as the cornerstone of the development of the graphene optical and electrical devices. The common used methods...
A 16-channel implantable microelectrode array (MEA) was designed and fabricated by Micro-electromechanical Systems (MEMS) technology. Then the electrode sites were modified with platinum/graphene oxide nanocomposites (Pt-GO) by one-step electrochemical deposition and later handled by cyclic voltammetry reduction in phosphate buffer solution. Finally, a Nafion thin film was coated on the MEA surface...
Graphene has been reported to show polarization-dependent optical absorption in the visible spectral range, that it shows more absorption for s-polarized light than p-polarized light. We study further on it and demonstrate that this unique property can be utilized to design a fiber optic sensor, which works in a similar way of surface plasmon resonance (SPR) fiber optic sensor. However, they are based...
This paper reports a novel electrochemical accelerometer for applications of wearable systems and smart skins. An original flexible accelerometer based on graphene electrodes and a PDMS microchannel on polyimide flexible print circuit (FPC) has been achieved by low-cost fabrication process. Instead of expensive platinum electrodes, a graphene layer was transferred to FPC to function as chemical inertness...
Today, heteroepitaxial GaN films on sapphire have focused on conventional two-step growth process using low temperature GaN buffer layer. Here, we show the direct growth of GaN films on sapphire by using a graphene layer at high temperature, which simplified the GaN growth process. The graphene is directly synthesized on non-catalytic sapphire substrate by chemical vapor deposition without problematic...
Large-area uniform monolayer epitaxial graphene (EG) was prepared by the thermal decomposition of 4H-SiC in optimized temperature field. With the increase of substrate diameter, the radial temperature fluctuation also becomes more drastic. The convex and flat temperature fields with different growth system configurations were obtained by VR-PVT software. The EG surface morphology was characterized...
With the assistance of in-situ grown graphene on the wafers, semi-insulating 4H-SiC wafers were etched in aqueous KOH using photo-electrochemical method. The etching rate was estimated to be at about 50nm/min. By the cross-sectional scanning electron microscope (SEM) images, triangular structure in a similar size and aligned in the same direction was found on (1–100) face. Whereas on the (11–20) faces,...
Recently graphene has attracted tremendous attention for its excellent properties Numerous novel graphene-based devices have come out, showing great potential of graphene for tunable applications at THz band In this paper, by stacking a monolayer of graphene on the top of the polymer substrate, a graphene-based tunable absorber is obtained owning to the voltage-controllable conductivity of graphene...
We have experimentally realized a broadband THz modulator in a total internal reflection geometry using SiO2/Si gated monolayer graphene. The modulation depth in our device is up to 83% over the range of 0.2–0.6 THz, and can be further improved by extending the size of our modulator and using multiple reflections.
In this work, we demonstrate a fiber laser based on graphene which is suspended in the air. Though the damage threshold of graphene is high, it's easy to be damaged when graphene is suspended in the air. And it will form a microvoid in the middle of the graphene which acts as a saturable absorber. A stable and polarization insensitivity mode-locked fiber laser can be realized based on this graphene.
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