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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
  • Signal-to-Noise Ratio (SNR)
  • Infinite Gain Multiple Feedback (IGMF)
  • Visible Light Communications (VLC)
  • LED
  • Trans-Impedance Amplifier (TIA)
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • University of Northumbria
  • University of Huddersfield
233 条数据
?? 中文（中国） ▾

  • Compact High Gain Leaky-Wave Antennas Based on Substrate Integrated Waveguide TE <sub/>220</sub> Mode

    摘要： In this paper, novel compact high gain broadband leaky-wave antenna (LWA) using TE220 high-order mode is proposed. The high-order mode antenna not only possesses more compact structure with higher gain, but also simpli?es the feeding network of the antenna array and relaxes processing tolerance. The radiation element consists of an SIW cavity etched with 2 × 2 slot array on the top surface, which is excited by a microstrip-slot coupling structure. Microstrip spoof surface plasmon polariton (SPP) is worked as a slow-wave transmission line (TL) to increase the beam scanning range of a four elements periodic array antenna. The antenna was simulated, optimized and fabricated, which veri?ed theoretical analysis. Experimental results show that the linearly polarized (LP) beam scanning antenna has a bandwidth of 53.5% (from 12.6 GHz to 21.8 GHz) with beam scanning range from ?24? to +32? and gain in the range of 10.2 dBi to 12.4 dBi. Then a linear-to-circular polarization converter is loaded to implement a circular polarization (CP) beam scanning antenna. The proposed antenna has the features of compact size, low pro?le, high gain, large beam scanning range and ?exible polarization conversion.

    关键词： high-order mode,high gain,spoof surface plasmon polariton,Beam scanning antenna

    更新于2025-09-19 17:13:59

  • Design of a substrate integrated waveguide matrix amplifier

    摘要： Developments in microwave systems have increased the need for matrix amplifiers, which provide both high gain and wide frequency bands. The aim of this paper is to design a novel 2 (cid:2) 4 matrix amplifier with a substrate integrated waveguide (SIW)-based power divider and combiner and a microstrip gain equalizer in the X and low Ku frequency bands. The proposed amplifier can be easily integrated with any microstrip, rectangular waveguide, or SIW-based circuits. The analysis and design of the amplifier is performed using two full wave simulators with different computational techniques (finite element method and finite integration technique) to verify the results. Simulation results show that the amplifier provides 16 dB gain with less than 4 dB ripple and more than 10 dB of input and output return losses in the frequency band of 8–15 GHz. This amplifier can be used as a wide band and high gain block in many microwave applications.

    关键词： substrate integrated waveguide,distributed structure,Matrix amplifier,gain-bandwidth improvement

    更新于2025-09-19 17:13:59

  • [IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Annual energy yield analysis of solar cell technology

    摘要： This paper presents a systematic procedure that can be used to create operational transconductance amplifiers (OTAs) for closed-loop operation using multiple low-gain stages to realize extremely high DC gain. Such devices are necessary to realize analog functions with demanding absolute accuracy requirements, e.g., high-resolution ADCs and DACs. The principle is based on the cascade of undamped integrators to realize large DC gains and a state-space derived controller to stabilize its operation in a closed-loop configuration. A programmable OTA fabricated in the IBM 130 nm CMOS process is used as a test vehicle to prove the design principle through its 2 to 5th-order realization. Measured data reveals DC gains ranging from 50 to 150 dB with a 3-dB bandwidth of 10 kHz and a unity gain frequency of 10 MHz. While this paper demonstrates the design principles using CMOS integrated circuits, the principle is general and can be applied to any type of circuit technology in integrated or discrete implementation. Moreover, the methods are easily automated as the principles are based on closed-form formulae as opposed to iterative numerical search techniques.

    关键词： integrated circuit implementation,Miller-C integrators,dominate-pole implementation,programmable amplifiers,Controller-based compensation,operational transconductance amplifiers (OTAs),discrete compensation,operational amplifiers (op-amps),ultra-high gain

    更新于2025-09-19 17:13:59

  • InAs/InP quantum dot VECSEL emitting at 1.5 μm

    摘要： A high-power InAs quantum dot (QD) vertical-external-cavity surface-emitting laser emitting at 1.5 lm is reported. The active region employs 20 layers of high-density Stranski–Krastanow InAs quantum dots on an InP substrate. The QD density and emission wavelength were independently adjusted by employing a double-cap growth sequence. Optimization of the spacer layer thickness and strain compensation rendered possible nucleation of a relatively high number of QD layers per antinode of the electromagnetic standing wave, which in turn enabled a high output power continuous wave operation of about 2.2 W. The operation wavelength could be tuned over 60 nm, taking advantage of the broadband gain characteristic of QD media.

    关键词： 1.5 lm emission,VECSEL,InAs/InP quantum dot,high-power,broadband gain

    更新于2025-09-19 17:13:59

  • [IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Dielectric and Plasmonic Vivaldi Antennas for On-Chip Wireless Communication

    摘要： The ?rst quanta image sensor jot with photon counting capability is demonstrated. The low-voltage device demonstrates less than 0.3e- r.m.s. read noise on a single read out without the use of avalanche gain and single-electron signal quantization is observed. A new method for determining read noise and conversion gain is also introduced.

    关键词： CMOS image sensor,high conversion gain,low read noise,photon counting,jot device,quanta image sensor

    更新于2025-09-19 17:13:59

  • A comparative clinical trial to evaluate efficacy and safety of the 308‐nm excimer laser and the gain‐switched 311‐nm titanium:sapphire laser in the treatment of vitiligo

    摘要： Background/purpose: Ultraviolet B (UVB) laser irradiation in a targeted manner is a reasonable treatment option for localized vitiligo. Recently, narrow‐band UVB gain‐switched 311‐nm titanium:sapphire lasers (TSL) were developed for the treatment of localized vitiligo. We aimed to compare efficacy, patient satisfaction, and safety between the conventional 308‐nm excimer laser (EL) and gain‐switched 311‐nm TSL in patients with vitiligo. Methods: The 13‐paired lesions from 10 patients who had small vitiligo patches were included in this prospective intra‐patient comparison trial. Each pair was randomly assigned to each laser treatment group and treated twice weekly for 12 weeks. The global photographic assessments by dermatologists, objective numerical assessments by imaging analyzer, and patient's satisfaction were used to evaluate the effectiveness. Adverse effects were also investigated at every visit. Results: All treated lesions showed improvement of about 50% after 12 weeks. There was no significant difference between EL‐ and TSL‐treated groups. Patient satisfaction and preference among the groups were also similar. Regarding safety, there were no serious adverse effects requiring cessation of the treatments; however, the severity score for persistent erythema (lasting >24 hours) was significantly lower in the TSL group than in the EL group. Conclusions: The gain‐switched 311‐nm TSL exhibited similar efficacy to the 308‐nm EL in treating vitiligo as well as improved safety. Therefore, the 311‐nm TSL is considered as a candidate device to replace the EL as a new and promising treatment option for localized vitiligo.

    关键词： 308‐nm Excimer laser,gain‐switched 311‐nm titanium:sapphire laser,vitiligo

    更新于2025-09-19 17:13:59

  • On the Analysis and Comparison of Decoupled Modal Gain Equalization Systems for Four-Mode (4a??M)-EDFAs

    摘要： Space-Division Multiplexing (SDM) has gained considerable interest as a promising means to increase transmission capacity per fiber. For proper use of this technology, optical components of transmission line including Erbium-Doped Fiber Amplifiers (EDFAs) need to be re-examined. In this work we analyze modal gain equalization systems obtained from extended Giles model for 4M-EDFA. We introduced a simpler method of calculation of two radial overlap factors extracted from the model using standard B-V curve thus proposing two decoupled systems for Modal Gain Equalization. In Decoupled Mode-Specific Pump Combination (MSPC) system so obtained, Maximum Differential Modal Gain (DMG) was reduced to 1.55 dB with mean gain of about 28.72 dB. For Modified Erbium Doped Profile (MEDP) system we obtained an optimum Multi-Well Profile. The maximum DMG here showed further reduction to 1.3254 dB with mean gain of about 24.24 dB. Further we report investigation on evolution of ASE for 4M-EDFA for the first time with new performance metric namely ASE ratio to indicate the deviation of noise between four modes. The ASE levels reached in MEDP are smaller than MSPC system thus enabling reduction in Noise Figure. Simulation results and comparison indicated that in MEDP, DMG is more sensitive to variation in length, concentration and wavelength. Our designed MEDP and MPC system as well as simple 4M-EDFA system gave good pre-amplification performance for data rates smaller than 15 Gb/s.

    关键词： Doping profiles,Erbium Doped Profile,Overlap Factors,Modal Gain Equalization,ASE Ratio,SDM Amplifiers

    更新于2025-09-19 17:13:59

  • [IEEE 2018 15th IEEE India Council International Conference (INDICON) - Coimbatore, India (2018.12.16-2018.12.18)] 2018 15th IEEE India Council International Conference (INDICON) - Switched-Inductor Based High Voltage Gain Step-up DC-DC Converter for Photovoltaic Micro-Inverter Application

    摘要： Traditional boost converter cannot offer a high voltage gain due to the conduction losses in the ESR of capacitor and DCR of inductor, at higher duty cycles. Therefore, traditional boost converter cannot be employed for voltage conversion in occasions that need very high voltage boosting such as the grid-connected photovoltaic micro- inverter. In this paper, a high voltage gain step-up converter, utilizing a switched-inductor (S-L) cell, is proposed. The input current of the suggested converter is continuous because of the presence inductor at source side that makes the input filter design easier. This converter produces very high output voltage at a lower duty cycle, which makes it suitable for photovoltaic micro-inverter application. The basic operation principles and steady-state analyses of the proposed step-up converter are discussed to derive the voltage gain and voltage/current stresses across each component. The proposed boost converter is finally simulated in MATLAB/Simulink to verify all theoretical analyses.

    关键词： high voltage gain,switched-inductor (S-L) cell.,micro-inverter,DC-DC step-up converter

    更新于2025-09-19 17:13:59

  • Net energy gain in direct laser acceleration due to enhanced dephasing induced by an applied magnetic field

    摘要： Even in the situation where an electron interacts with a single plane wave, the well-known dynamical adiabaticity can be broken when an applied magnetic field is present, which will act to increase the dephasing rate of the electron during the interaction. Here we demonstrate this for the case where there is a uniform static magnetic field which is oriented either parallel or perpendicular to the electric field of the incident plane wave, and perpendicular to the direction of its propagation. The described energy gain phenomenon has direct relevance to laser-plasma interactions that involve external magnetic fields generated by laser-driven capacitor coils.

    关键词： net energy gain,direct laser acceleration,magnetic field,laser-plasma interactions,dephasing

    更新于2025-09-19 17:13:59

  • Influence of Laser Power on Grain Size and Tensile Strength of 5A90 Al–Li Alloy T-joint Fabricated by Dual Laser-Beam Bilateral Synchronous Welding

    摘要： Dual laser-beam bilateral synchronous welding is introduced to produce the 2.5 mm thick 5A90 Al–Li alloy T-joint. The grain morphology and grain size of weld metal (WM) in the T-joint are analyzed and calculated. The tensile experiment, scanning electron microscopy and energy disperse spectroscopy are respectively employed to study the tensile strength, fracture morphology and chemical composition of the T-joint. The results reveal that when the laser power is increased from 2500 to 3000 W, the grain sizes of fine-grained layers and columnar dendrites near the fusion line are significantly reduced. Conversely, that of equiaxed dendrites at the WM center is not sensitive to the variety of laser power. Moreover, the degree of elemental segregation in WM near the fusion line is also aggravated with the increasing of the laser power. The tensile strength of the T-joint with the laser power of 2500 W is significantly higher than that with the laser power of 3000 W. The tensile fracture locations are occurred in the weld toe with obvious pores, shear dimples and tear ridges, which are the typical characteristics of ductile fracture. Besides, the chemical compositions of the second phase particles in the WM are more sensitive to than the variation of laser power compared with that of the matrix.

    关键词： T-joint,5A90 Al–Li alloy,Tensile strength,DLBSW,Gain size

    更新于2025-09-16 10:30:52