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16-channel dual-tuning wavelength division multiplexer/demultiplexer
摘要： A 16-channel dual tuning wavelength division multiplexer/demultiplexer based on silicon on insulator platform is demonstrated, which is both peak wavelength tunable and output optical power tunable. The wavelength division multiplexer/demultiplexer consists of an arrayed waveguide grating for wavelength division multiplexing/demultiplexing, a heater for peak wavelength tuning and a variable optical attenuator based on p–i–n carrier-injection structure for optical power tuning. The experimental results show that the insertion loss on chip of the device is 3.7 dB–5.7 dB and the crosstalk is 7.5 dB–9 dB. For the tunability of the peak wavelength, 1.058-nm wavelength tunability is achieved with 271.2-mW power consumption, and the average modulation efficiency is 3.9244 nm/W; for the tunability of the optical power, the optical power equalization is achieved in all 16 channels, 20-dB attenuation is achieved with 144.07-mW power consumption, and the raise/fall time of VOA is 35 ns/42 ns.
关键词： arrayed waveguide grating,variable optical attenuator,silicon photonics
更新于2025-09-23 15:22:29
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Microstrip broadband thin-film attenuators without via-hole-ground at millimeter wave frequencies
摘要： A comprehensive design methodology for microstrip broadband attenuators is presented. Closed-form design equations are given for two types of distributed attenuators. The attenuators are based on a cascade connection of thin-film resistors and microstrip line sections. The structure provides maximally flat attenuation and wideband performance without the need of plated via holes to ground, facilitating manufacture as well as achieving proper performance at millimeter wave frequencies. Experimental results demonstrate the validity of the technique applied to 3 dB and 13 dB broadband attenuators on alumina substrate up to 67 GHz. The proposed topology can be applied not only to MIC, but also to MMIC designs at the highest frequencies.
关键词： MM-wave,Thin-film microwave attenuator,Microstrip circuit
更新于2025-09-19 17:15:36
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Laser-Damage Attack Against Optical Attenuators in Quantum Key Distribution
摘要： Many quantum key distribution systems employ a laser followed by an optical attenuator to prepare weak coherent states in the source. Their mean photon number must be precalibrated to guarantee the security of key distribution. Here we experimentally show that this calibration can be broken with a high-power laser attack. We test four fiber-optic attenuator types used in quantum key distribution systems, and find that two of them exhibit a permanent decrease in attenuation after laser damage. This results in higher mean photon numbers in the prepared states and may allow an eavesdropper to compromise the key.
关键词： laser damage,optical attenuator,quantum key distribution,security
更新于2025-09-19 17:13:59
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Electromagnetic Wave Absorbers (Detailed Theories and Applications) || Theory of Special Mediums
摘要： In this section, chiral, magnetized ferrite, and metamaterial media are taken up as special media related to the EM-wave absorber and attenuator, and these theoretical treatments of EM fields are described in detail.
关键词： EM-wave absorber,magnetized ferrite,chiral medium,metamaterial,attenuator
更新于2025-09-19 17:13:59
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[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) - Genetically Optimized Design of Ultra-Compact and Highly Efficient Waveguide Crossing, Optical Attenuator and Reflector
摘要： In this study, we present the design of ultra-compact and highly efficient photonic integrated devices by applying a meta-heuristic approach. Here, we integrated the three-dimensional finite-difference time-domain method into an evolutionary optimization algorithm to specifically design waveguide crossing, optical attenuator and reflector. The proposed devices have ultra-compact footprints of 2×2 μm2 with slab thickness of 220 nm and consist of 100×100 nm2 silicon or air cells on a SiO2 substrate. We demonstrate an ultra-compact waveguide cross on silicon photonic platform with transmission efficiency greater than 80% and with a negligible crosstalk. Also designed attenuator and reflector devices are providing 3 dB signal reduction and over 85% reflectivity, respectively. All of the devices are excited by a fundamental transverse-electric mode guided in a silicon waveguide with a width of 500 nm. Throughout the optimization process, fabrication constraints are taken into account to enable the realization of the designed devices in applications. The introduced design method can be further expanded to form either diverse photonic integrated devices or even plasmonic devices.
关键词： reflector,photonic integrated devices,optimization,waveguide crossing,optical attenuator
更新于2025-09-16 10:30:52
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A Tunable Attenuator Based on a Graphene-Loaded Coupled Microstrip Line
摘要： In this article, a novel tunable attenuator based on graphene is proposed. It consists of a coupled microstrip line (CMSL) and two graphene-covered gaps in MSLs. By utilizing a biased voltage, the surface impedance of graphene can be tuned, and then, the re?ective coef?cient at two ports of the coupler can be correspondingly adjusted; therefore, the performance of the attenuator can be modi?ed. The design procedure and the mechanism of the attenuator are demonstrated in detail. To verify the analysis, a prototype was fabricated and tested. According to the measured results, the fabricated attenuator presents the favorable attenuation tuning range from 3 to 20 dB at the operating frequency from 1 to 6 GHz, and it is just 38 mm × 22 mm in size. Besides, |S11| of the attenuator can always be maintained at a low level, and the phase of S21 is substantially unchanged.
关键词： gap in MSL,dynamically tunable,coupled microstrip line (CMSL),Attenuator,graphene
更新于2025-09-16 10:30:52
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Measurements of High Power Levels of Laser Radiation by Pass-Through Receivers
摘要： The problem of developing measuring instruments for high levels of laser power of the pass-through type was posed and solved. Methods for solving the problem are presented. A measuring instrument has been developed, in which a two-step circuit design is applied for power attenuation of the laser beam to an operating level as measured by the radiation detector. It is shown that due to the original design of the attenuation steps and their arrangement in relation to the laser beam it is possible to achieve values of the attenuation coefficient of (0.2–0.4)·1010 and to measure power up to 10–15 kW without forced cooling of elements of the measuring instrument. Application of the design of steps makes it possible to reduce the dimensions of the measuring instrument and pass practically all radiation to the output without changing the characteristics of the initial laser beam. The measuring instrument that was developed differs from known analogs and is suitable for work with process lasers. For reliable measurement of laser radiation power, the conditions were determined for selecting the time constant of integration of the radiation detector. The connection between the time constant of integration of the radiation detector and the geometrical characteristics of the measuring instrument is shown.
关键词： attenuator,reflector,integrating sphere,laser power,attenuation coefficient
更新于2025-09-12 10:27:22
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[IEEE 2019 14th European Microwave Integrated Circuits Conference (EuMIC) - Paris, France (2019.9.30-2019.10.1)] 2019 14th European Microwave Integrated Circuits Conference (EuMIC) - HEMT Small-Signal Modelling for Voltage-Controlled Attenuator Applications
摘要： Multi-bias measured and simulated S parameters are presented to validate the extension of an accurate on/off state HEMT switch small-signal modelling procedure to analog attenuator applications. Good agreements between measured and simulated multi-bias S parameters of the HEMT with a gate resistor are achieved by using only a common-gate real test-structure (without the gate resistor), which not only confirm the validity of the modelling for both digital and analog attenuator applications, but also validate the applicability of the capacitance network and extraction methods under more bias conditions.
关键词： small-signal model,voltage-controlled attenuator (VCA),high electron-mobility transistor (HEMT),monolithic microwave integrated circuit (MMIC)
更新于2025-09-12 10:27:22
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Optoelectronic attenuation behavior of Al2O3/ZnO nanolaminates grown by Atomic Layer Deposition
摘要： Zinc oxide (ZnO) and aluminum oxide (Al2O3) nanolaminates deposited in a homemade Atomic Layer Deposition (ALD) system are presented. In this work, three samples with a multi-films structure formed by four Al2O3/ZnO bi-layers of 20 nm were synthetized by thermal ALD. To analyze the optoelectronic response, the thickness of the Al2O3 was varied at 1%, 3% and 5 % of the total bi-layer width for each sample. A curve of saturation was performed by means of spectroscopic ellipsometry to determine the dose time for the precursors. As a result, the synthesis of ZnO films was obtained using 50 ms for Diethylzinc dosification. To estimate the thickness of Al2O3 layers of the nanolaminates, X-ray photoelectron spectroscopy was used. To characterize the optical response of the samples, room temperature cathodoluminescence spectra were obtained from different multilayer structures. The attenuation of the luminescence was related to the integration of the aluminum oxide on the nanolaminates. As a result, a correlation between the reduction of the luminescence intensity of the multilayer and the increment of the Al2O3 layer thickness was demonstrated. The accurate control on the deposition of thin films makes this process a suitable method to be used in the optoelectronic industry as a precise coating technique with attenuation applications.
关键词： ZnO,Al2O3,ALD,nanolaminates,Optoelectronic attenuator
更新于2025-09-10 09:29:36