- 标题
- 摘要
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- 实验方案
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Extenuation of phase shift influenced nonlinear impairments in fiber optics network
摘要： Transmission of ultrahigh data rates through fiber optics networks (FONs) over long transmission distances in an intensity-dependent refractive index medium suffers from nonlinear self-steepening (NSS) and stimulated Raman scattering (SRS). In this paper, a FON model is proposed to compensate NSS and SRS impairments, using a theoretical model and its verification through simulation for different set of parameters. The proposed FON is designed to support 8, 16, and 32 channels with dual polarization quadrature phase shift keying modulation format. The analysis is performed for a range of values for the transmission medium including nonlinear effective area, nonlinear refractive index, and nonlinear dispersion. Moreover, the performance of the proposed model is evaluated in terms of launch power, polarization variations, received power, and length of transmission fiber. The overall work is analyzed for transmission distances up to 1200 km for performance metric of bit error rate, eye diagram, and received symbols constellations diagram.
关键词： WDM,stimulated Raman scattering,quadrature phase shift keying,fiber optics networks,nonlinear self-steepening,phase shift
更新于2025-09-16 10:30:52
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Design of Complex Weighted Feeding Network Based on Generalized Coupled-Resonator Filter Theory
摘要： Feeding network with complex weight has important prospect in various applications. In this article, the design of complex weighted feeding network based on generalized coupled-resonator filter theory is proposed. To design the power and phase distribution all-in-one, a novel type of multifunctional generalized filter is proposed. It has abilities of impedance transformation, phase shift, and filtering. Then, the design method of the network with arbitrary power distribution and arbitrary phase distribution by this generalized filter is demonstrated. Four different design examples are executed to validate the proposed theory. This proposed network overcomes many shortages of these existing methods and possesses several additional advantages, such as simple structure, designable bandwidth, and filtering function.
关键词： phase shift,impedance transformation,Complex weight,generalized filter,feeding network
更新于2025-09-16 10:30:52
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Exact distributions for bit error rate and channel capacity in free-space optical communication
摘要： Bit error rate (BER) and channel capacity are two important metrics to assess the performance of free-space optical communication (FSOC) systems. Due to the fading of the optical signal owing to the atmospheric effects, these two quantities behave as random variables. Most of the studies in this direction have focused on the calculation of only the average of these quantities. However, since the complete information about a random variable is encoded in its distribution, it is more informative to examine the latter itself. In this work, the authors derive exact probability density function (PDF) expressions for the BER and the channel capacity for an arbitrary irradiance model. In particular, they investigate these exact results for log-normal, gamma-gamma, and K distributions. For the BER analysis, they focus on the binary phase shift keying and quadrature phase shift keying modulation schemes. The authors' analytical reults are found to be in conformity with Monte Carlo simulations. The exact PDFs of the BER and the channel capacity reveal that there are several instances when the average is unable to capture the actual behaviour of these quantities, and therefore one must be careful in drawing conclusions based on the first moment only.
关键词： binary phase shift keying,bit error rate,quadrature phase shift keying,gamma-gamma distribution,channel capacity,log-normal distribution,K distribution,probability density function,free-space optical communication
更新于2025-09-12 10:27:22
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Optical Fiber Communications (Principles and Applications) || Fiber Optic Sensors
摘要： Recent advances in fiber optic technology and optoelectronic devices led to emergence of fiber optic sensors. With the availability of highly sensitive detectors and material loss almost approaching to negligible, it is possible to sense even slight variations in intensity level, phase shift and wavelength from external distresses on the optical fiber itself. This is the fundamental concept of fiber optic sensors. The primary function of a fiber optic sensor is to measure or monitor a physical quantity such as temperature, pressure, corrosion, humidity, and similar environmental factors. The basis of measurement is the net effect on its intensity modulation, operating wavelength, phase angle of the incident optical ray, or polarization of the light propagating through the optical fiber.
关键词： physical quantity measurement,fiber optic sensors,phase shift,wavelength,intensity modulation
更新于2025-09-12 10:27:22
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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - Wideband and Continuously Tunable Microwave Photonic Phase Shifter Based on an Active InP/InGaAsP Microring Resonator
摘要： We propose and experimentally demonstrate a wideband and continuously tunable microwave photonic (MWP) phase shifter based on an active InP/InGaAsP microring resonator (MRR) incorporating two semiconductor optical amplifiers (SOAs) and a phase modulator (PM). By tuning the gain provided by the SOAs, the loss in the ring cavity can be compensated and the extinction ratio of a resonance is decreased to nearly 0 dB, while maintaining the optical phase shift range within the resonance bandwidth. A theoretical analysis is performed. The key advantages of using the proposed MRR to achieve a microwave phase shifter are that the power variation at the output of the phase shifter is minimized during phase tuning and the microwave phase can be continuously tuned by tuning the PM in the MRR theoretically. The proposed phase shifter is experimentally demonstrated. A continuously tunable microwave phase shift over a phase tuning range of 291° from 5 GHz to 20 GHz by tuning the injection current to the PM is implemented. The microwave power variation is lower than 5 dB.
关键词： integrated optics devices,ring resonators,phase shift
更新于2025-09-12 10:27:22
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Detecting the Extremely Small Angle of an Axicon by Phase-Shifting Digital Holography
摘要： Axicon is an optical element that can be used to produce high-quality Bessel beams efficiently. In general, the smaller the base angle of the axicon is, the longer the diffraction-free distance of the generated Bessel beam will be. Therefore, axicon with an extremely small base angle is important for the generation of Bessel beam. However, the measurement of an extremely small base angle is a challenge. Here, we applied the phase-shifting digital holography in the measurement of axicon angle. The errors of the three measured axicons with base angles of 0.5°, 1°, and 1° were 1.94%, 4.43%, and 1.63%, respectively.
关键词： digital holography,axicon,phase measurement,phase shift
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || Quantitative measurement of the charge distribution along a tungsten nanotip using transmission electron holography
摘要： The measurement of the charge distribution along a tungsten nanotip using an electron-optical phase shift technique is presented. The charge distribution is measured by applying a voltage to the tip and recording the resulting phase shift of the electron beam. The results show that the charge distribution is not uniform and is affected by the tip geometry and the applied voltage. The technique provides a new method for measuring charge distributions at the nanoscale.
关键词： charge distribution,tungsten nanotip,nanoscale measurement,electron-optical phase shift
更新于2025-09-11 14:15:04
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Phase shift formulas in electro-optical crystals with an arbitrary incident direction
摘要： The calculation of the phase shift in electro-optical crystals is related to an extensive range of optical devices. A set of analytical phase shift formulas at arbitrary incidence angle and azimuth angle for a plane-parallel electro-optical crystal plate is derived. This enables us to analyze the phase shift induced by an electro-optical crystal with an arbitrary incident direction. As an example, the derived formulas are used to investigate the influence of incidence angle and azimuth angle on the phase shift in a lithium niobate crystal plate. For the field-free lithium niobate crystal, the phase shift depends only on the incidence angle. In contrast, when an external electric field is applied to the crystal, the phase shift is not only strongly influenced by the incidence angle, but also periodically changes with the azimuth angle. In order to validate the correctness of the derived formulas, the experiments are also conducted. The theoretical results are proved to be in good agreement with the experimental results.
关键词： Electro-optical crystal,Phase shift,Biaxial crystal,Birefringent,Uniaxial crystal
更新于2025-09-11 14:15:04
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A high sensitive SH-SAW biosensor based 36° Y-X black LiTaO3 for label-free detection of Pseudomonas Aeruginosa
摘要： A label-free and high sensitive shear horizontal surface acoustic wave (SH-SAW) biosensor for the nucleic acid detection of Pseudomonas Aeruginosa was developed in this work. An effective detection cell was fabricated by dint of acrylic material. The base frequency of the SH-SAW biosensor fabricated on 36°Y-X rotated black LiTaO3 piezoelectric substrate was 210 MHz. The self-assembled monolayer was formed on the gold surface of the sensitive area, and the increase of mass loading in the sensitive area leads to phase shift of SH-SAW. In this work, the detection limit has been improved by 3–4 times than that in our previous works, which is 1 nmol/L for the nucleic acid of the Pseudomonas Aeruginosa. And the phase shifts related to detection sensitivity are also elevated to 4 ° after the specific binding of the ss-DNA probes and the complementary sequences. In this study, the plot of phase shift against the logarithm of concentration of Pseudomonas aeruginosa nucleic acid was found to be linear over the range from 0.1 nmol/L to 1000 nmol/L with a correlation coefficient 0.98777. The detection limit as low as 0.28 nmol/L was achieved for Pseudomonas aeruginosa nucleic acid in this paper.
关键词： SH-SAW,Biosensor,Black LiTaO3,Limit of detection,Phase shift
更新于2025-09-11 14:15:04
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Optimization of Epsilon-and-mu-near-zero Refractive Index Photonic Structure to Design Unidirectional Transmission Device
摘要： In this study, we introduce a novel approach for designing an unidirectional transmission device by using a photonic crystal (PC) structure that exhibits the properties of epsilon-mu-near-zero media. The selected PC structure consists of dielectric rods and positions of certain preselected rods in y-direction are optimized via an evolutionary algorithm to obtain the unidirectional transmission of light. Finite-difference time-domain (FDTD) method is used to perform numerical analyses for the proposed device. In addition, experiments are carried out at microwave frequencies to demonstrate the unidirectional light transmission. It is shown that a good agreement between numerical calculations and experimental measurements is achieved.
关键词： phase shift,mode order converter,photonic crystals,differential evolution algorithm,integrated optics
更新于2025-09-10 09:29:36