- 标题
- 摘要
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- 实验方案
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Increase of an Output Optical Signal of an Acousto-Optic Monochromator upon Frequency Modulation of a Control Signal
摘要： An angular aperture of an acousto-optical filter upon a linear frequency-modulated (chirp) control signal has been experimentally studied for the first time. The results of studying the spectral and angular dependences of the spectral transmission function of a filter upon a frequency modulation have shown the possibility of an efficient increase of the output optical signal. The value of the optical signal was increased by 2000 times using the selected design of the acousto-optical filter. This makes it possible to obtain a gain in the measurement time or in the value of the detected optical signal. Such an increase of the output signal upon a chirp control signal is provided by the increase of the angular aperture and broadening of the spectral transmission bandwidth together with the required proportional increase of the control signal power.
关键词： angular aperture,output optical signal,spectral transmission function,acousto-optical filter,frequency modulation
更新于2025-09-23 15:21:01
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A Simple WiMAX and RFID band Notched UWB Bandpass Filter and It's susceptibility Study
摘要： An ultra-wideband (UWB) bandpass filter (BPF) with a fractional bandwidth (FBW) of about 110%, transmission zero at the high frequency edge, and band notches at the worldwide interoperability for microwave access (WiMAX) and radio frequency identification (RFID) band is presented in this paper. The filter is based on single short-circuited stub, U-shaped defected ground structure (DGS) array, two U-shaped resonators and two stepped impedance resonators (SIRs). The filter is compact and exhibits a selective filtering characteristic equivalent to a 3-pole Chebyshev filter. The design procedure has been described and verified by full-wave electromagnetic (EM) simulation and measurement. The proposed filter has low insertion loss, sharp rejection, and excellent in and out band performance. Due to its applications in WiMAX and RFID systems, the filter may be subjected to high EM radiation from the antenna and nearby sources. Therefore, susceptibility study of such filter is very important. Hence, the susceptibility study of the band notched UWB bandpass filter has been carried out by subjecting the structure to an interference source.
关键词： Microstrip band pass filters (BPFs),notch band,transmission zero,ultra-wideband (UWB) filters
更新于2025-09-23 15:21:01
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Misfit-Dislocation Distributions in Heteroepitaxy: From Mesoscale Measurements to Individual Defects and Back
摘要： We provide an in-depth characterization of the dislocation distribution in partially relaxed Si0.92Ge0.08/Si(001) films. This is achieved by an innovative and general method, combining two state-of-the-art characterization techniques through suitable modeling. After having inferred the dislocation positions from transmission-electron-microscopy images, we theoretically reproduce scanning-x-ray-diffraction-microscopy tilt maps measured on the very same region of the sample. We obtain a nearly perfect match between model predictions and experimental data. As a result, we claim that it is possible to establish a local, direct correlation between the dislocations revealed by the transmission-electron-microscopy analysis and the measured lattice tilt distribution.
关键词： heteroepitaxy,dislocation distribution,scanning x-ray diffraction microscopy,transmission electron microscopy,lattice tilt distribution
更新于2025-09-23 15:21:01
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Wave propagation of the perturbed nonlinear Schr?dingers equation in the nonlinear left-handed transmission lines
摘要： This paper secures chirped dark and bright solitons of the perturbed nonlinear Schr¨odinger equation with parabolic law nonlinearity and self-steepening effect in the nonlinear left-handed metamaterials (NLHMs). We use the ansatz method, sine-cosine, csch function method and the auxiliary equation method to fall out the various soliton solutions. In view of the results obtained, rational, hyperbolic and trigonometric solutions emerge and there are new in CRLH TL. The existence criteria of these solutions are also discussed. Finally, we observed that the use of the auxiliary equation method leads to the abundant and efficient solutions than the other methods.
关键词： integrability,composite right/left-handed transmission lines,Soliton
更新于2025-09-23 15:21:01
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Influence of Reactive Ion Etching on THz Transmission and Reflection Properties of NiCr Film Deposited on a Dielectric Substrate
摘要： Enhanced terahertz (THz) absorption of NiCr film deposited on a dielectric substrate has been proven by applying a reactive ion etching (RIE) treatment to the dielectric film. Nano-scale nickel-chromium (NiCr) thin films are deposited on RIE treated silicon dioxide (SiO2) dielectric substrates to study the transmission and reflection characteristics. Experimental results suggest that both transmission and reflection of NiCr film are weakened by the RIE treatment. The most significant decrease of transmission is observed in (1 ~ 4) THz while that of reflection occurs in (1.7 ~ 2.5) THz band. The decrease of both transmission and reflection is more significant for NiCr film with higher thickness. The RIE treatment, which induces a roughened surface of SiO2 substrate and increases the effective surface area of NiCr film, enhances the absorption and weakens the transmission and reflection of THz radiation.
关键词： NiCr thin film,transmission,RIE,THz,reflection,absorption
更新于2025-09-23 15:21:01
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Tunable quad-band transmission response, based on single-layer metamaterials
摘要： We investigated the electromagnetically induced transparency (EIT)-like effects in planar metamaterials (MMs) at microwave (GHz) frequencies. The specific MMs that were used in this study consist of cut-wire resonator/ring resonator, which achieved the dual EIT-like effects in a single-layer through the bright- and quasi-dark-mode coupling and the lattice mode coupling. In addition, by varying the distance between the two resonators, the quad-band EIT spectral response in the microwave region was obtained, and the group refractive index at the EIT-like resonance of proposed design reached up to 4,000. This study provides the design approach to the multispectral EIT-like effects and might suggest potential applications in a variety of fields, for example, low-loss slow-light device, multiple switching sensor, and other sensing devices.
关键词： microwave frequencies,slow-light device,quad-band transmission,electromagnetically induced transparency,metamaterials
更新于2025-09-23 15:21:01
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[IEEE 2018 Systems of Signal Synchronization, Generating and Processing in Telecommunications (SYNCHROINFO) - Minsk (2018.7.4-2018.7.5)] 2018Systems of Signal Synchronization, Generating and Processing in Telecommunications (SYNCHROINFO) - On one principle of monitoring the network of optical transmission systems
摘要： The paper considers one new principle of monitoring the network of optical transmission systems. A new scheme of a device for monitoring is compiled and the principles of operation of this device are analyzed. Defined technical management of failures as a warning, detection and reaction to malfunctions. Failures are defined as interruptions to the normal operation of the network and include random interrupts, as well as losses of photons (or solitons), that can be performed by a service failure or eavesdropping. For this purpose, the functionality of the monitoring device and the algorithm for optical networks with different wavelengths have been expanded to be used in backbone, passive optical networks to determine the location of the cliff, the location of the eavesdropping, and unauthorized attacks. The enhancement capability is based on the study of other optical network switches, optical elements, multiplexers of / output, optical cross connections, wavelength converters, optical line terminals, etc. The vulnerability of these elements / or depends on manufacturing technology, and therefore, it is possible to consider the different types and forms of attenuation of optical signals, optical line breaks, loss and attack. The new design of the optical switch is applied, as a result, when the failure, attenuation and loss of optical signals are detected, the active port automatically switches to another port and simultaneously reports this to the central terminal device.
关键词： optical switchboard,translucent mirror,monitoring device,networks of optical transmission systems
更新于2025-09-23 15:21:01
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Handbook of Exoplanets || Exoplanet Atmosphere Measurements from Transmission Spectroscopy and Other Planet Star Combined Light Observations
摘要： It is possible to learn a great deal about exoplanet atmospheres even when we cannot spatially resolve the planets from their host stars. In this chapter, we overview the basic techniques used to characterize transiting exoplanets – transmission spectroscopy, emission and re?ection spectroscopy, and full-orbit phase curve observations. We discuss practical considerations, including current and future observing facilities and best practices for measuring precise spectra. We also highlight major observational results on the chemistry, climate, and cloud properties of exoplanets.
关键词： Observing facilities,Transmission spectroscopy,Emission spectroscopy,Climate,Re?ection spectroscopy,Cloud properties,Exoplanet atmospheres,Phase curve observations,Atmospheric chemistry
更新于2025-09-23 15:21:01
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Frequency Selective Surface for Infrared Transmission Suppression at Atmospheric Window
摘要： A double screen infrared frequency selective surface (FSS) with dual transmission stopbands was proposed and numerically investigated. Simulation results show that the infrared transmittance of the structure is lower than 10% in mid-infrared band (3~5 μm) and far-infrared band(8 ~14 μm).This structure is polarization insensitive to the incident electromagnetic waves. For a wide range of incident angles from 0° to 60°, the infrared transmittance of the structure is still lower than 25% in the band of interest. Compared with black body, the radiation ratio of structure is lower in the MWIR and LWIR ranges. The structure provide the potential applications for infrared stealth.
关键词： Infrared stealth,Transmission suppression,Atmospheric windows,Frequency selective surface
更新于2025-09-23 15:21:01
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Stopband-Extended and Size-Miniaturized Low-Pass Filter with Three Transmission Zeros
摘要： This paper presents a compact structure composed of an upper high-impedance transmission line, a middle extended parallel coupled line, and a pair of inter-coupled symmetrical stubs. Detailed investigation into this structure based on an equivalent circuit analysis reveals that this proposed structure exhibits a quasi-elliptic low-pass filtering response with three transmission zeros. Moreover, the positions of the three transmission zeros can be tuned and reallocated flexibly by choosing the proper circuit parameters. Finally, the design concept is validated through the design, fabrication, and measurement of two exemplary low-pass filters (LPFs) with one single unit and two cascaded asymmetric units. The measured results agree well with the simulated results. In addition, in the range of 1.42 fc to 7.03 fc, the fabricated quasi-elliptic LPFs experimentally demonstrate a very wide upper-stopband of 20 dB using a compact size of only 0.0089λg2, where λg is the guided wavelength of a 50 ? transmission line at the central frequency.
关键词： transmission zero,Low-pass filter (LPF),compact size,wide stopband
更新于2025-09-23 15:21:01