- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Optical Fiber Communications (Principles and Applications) || Optical Measurements
摘要： Optical measurements are necessary to verify the operational characteristics of the optical fiber communication link. Various measurement techniques and special-purpose test equipments are employed for determining key performance parameters of the constituent components and devices including the optical fiber. It is quite obvious that optical measurements are needed at different levels of research and design, manufacturing and production of optical components and devices, installation and commissioning of optical fiber communication systems in the field. There is wide variety of optical measurement and test equipments used. These include optical power meter, optical oscilloscope and spectrum analyzer, optical time-domain reflectometer (OTDR), optical waveform analyzer, connector inspection microscope, dispersion analyzer, live fiber detector, talk-set, optical test set (combined source and power meter), etc. All these measurements are wavelength specific. Fiber attenuation and occurrence of faults in the optical fiber link is the main concern in ensuring the desired performance. There are several challenges involved with optical measurements like multiple wavelengths/channels, high optical power levels, need to carry tests remotely along with a high degree of automation.
关键词： OTDR,optical measurements,spectrum analyzer,optical power meter,optical fiber communications
更新于2025-09-12 10:27:22
-
Hot carrier dynamics in a dispersionless plasmonic system
摘要： Hot carrier dynamics in a broadband, dispersionless, plasmonic structure are studied using pump-probe measurements with 45 fs time resolution. The results obtained by simultaneous measurement of differential transmittance and reflectance show the influence of pump generated carriers on the probe generated plasmons. The dependence of decay time on the pump fluence is linear for the interband and intraband carrier excitation near the L-symmetry point in gold. However, 1.908 eV pump excitation, which allows both interband transition at the X-symmetry point and intraband excitation at the L-symmetry point, shows quadratic dependence of decay time on the pump fluence. Degenerate pump-probe measurements at 1.55 eV, which allow L-valley intraband excitations, highlight the difference in surface (reflection) and the bulk (transmission) mechanisms. Hot carrier relaxation time is in the 1–3 ps range for different excitation energies. Rise time, governed by the plasmon to hot carrier conversion and electron-electron scattering processes, is about 200 ± 35 fs for the hot carrier and hot plasmon excitation cases that increased to about 485 ± 35 fs when the pump is resonant with the interband transition at the X-symmetry point. Results show that the hot carrier dynamics are governed by the bulk metal band structure. The dipole matrix element for each of the transitions is estimated by density matrix calculations.
关键词： pump-probe measurements,gold band structure,differential transmittance,reflectance,plasmonic system,hot carrier dynamics
更新于2025-09-12 10:27:22
-
[IEEE 2019 IEEE 15th International Conference on Automation Science and Engineering (CASE) - Vancouver, BC, Canada (2019.8.22-2019.8.26)] 2019 IEEE 15th International Conference on Automation Science and Engineering (CASE) - Iterative learning control for power profile shaping in selective laser melting
摘要： Selective laser melting (SLM) can be used to manufacture functional metal parts with complex geometries that cannot be produced by traditional manufacturing methods. However, SLM process control cannot yet guarantee the end part quality required for critical applications. The application of model-based control strategies to SLM is complicated by both the closed architecture of industrial SLM machines and the lack of suitable control-oriented process models. In this paper we (1) present an open-source SLM printer that allows implementation of the on-the-fly power adjustment and (2) use a data-driven method, iterative learning control (ILC) to learn the suitable laser power profile using the melt pool emission measurements from a coaxial camera. We demonstrate the effectiveness of the proposed ILC approach through experiments on the open-source SLM machine.
关键词： iterative learning control,laser power profile,open-source SLM printer,Selective laser melting,melt pool emission measurements
更新于2025-09-12 10:27:22
-
Recycled polyolefin as dielectric substrate for patch antennas
摘要： High-performance antennas operating at ultra-high frequency (UHF) are typically designed and fabricated using specialized radio frequency (RF) materials with low loss and consistent properties. This paper proposes and investigates the use of recycled polyolefin (high-density polyethylene and polypropylene) which is not specifically manufactured for RF applications and thus with unknown RF properties, as dielectric substrate for high-performance UHF patch antennas. As a demonstrative application, a polarization-reconfigurable patch antenna with dual feeds is designed and fabricated using adhesive copper foil on recycled polyolefin substrate. Depending on the feed’s magnitude and phase, different types of linear and circular polarizations can be achieved. The point of resonance for both ports is centered at 915 MHz with 10 dB return loss and bandwidth of 28 MHz. Port isolation is as low as ?17 dB with peak linear and circular gain of 7.0 dBi, and 7 dBiC, respectively, observed in all polarizations. The resulting antenna not only performs well, but is also lightweight, low moisture absorbent, mechanically sturdy, inexpensive and ecologically friendly arising from its use of recycled materials.
关键词： microstrip antennas,dielectric materials,polarization-reconfigurable,UHF antennas,dielectric measurements,recycled polyolefin
更新于2025-09-12 10:27:22
-
[IEEE 2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP) - Bochum, Germany (2019.7.16-2019.7.18)] 2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP) - Characterization of Liquid Crystals Using a Temperature-Controlled 60 GHz Resonator
摘要： This paper presents a resonant liquid crystal (LC) characterization at 60 GHz using a temperature controlled automated measurement setup. For the measurements the resonator is perturbed with LC inside a thin silica quartz tube. The LC orientation is accomplished by means of permanent rare earth magnets. Measurements are performed at 20 ?C. The investigated LC is the GT3-23001 mixture from Merck KGaA. The extracted values are compared with characterization results at 19 GHz. The extracted permittivities are ranging from 3.14 to 2.43 and the loss tangents from 0.0035 to 0.0191 for parallel and orthogonal orientation, respectively.
关键词： microwave measurements,material characterization,resonator,liquid crystal,millimeter wave
更新于2025-09-12 10:27:22
-
Highly reliable and transparent Al doped Ag cathode fabricated using thermal evaporation for transparent OLED applications
摘要： Here, we report a highly reliable and transparent cathode (TC) for transparent organic light emitting diode (TOLED) applications. The cathode layer is fabricated by co-deposition of silver (Ag) and aluminum (Al) metals using thermal evaporation. The atomic percentages of Al and Ag are fixed at 96 at% and 4 at%, respectively. TC shows transmittance at 520 nm (T@520nm) of 83.5% and sheet resistance as low as 7.0 Ω/□. Almost no specific agglomeration of Ag:Al (4%, 14 nm) is noticed by the thermal annealing of fabricated cathode at 85 °C, 240 h. The fabricated TOLED with this Ag:Al (4%, 14 nm) cathode shows an excellent electron injection property with a T@520nm of 83.5%, and achieved current efficiencies of 36 and 18 cd/A from bottom and top sides emissions, respectively. It is argued that the Al-doped Ag film could become an effective, feasible alternative to the existing transparent conducting electrode for TOLED applications.
关键词： Ag:Al cathode,SEM and XPS measurements,Transparent OLED,transparent cathode
更新于2025-09-12 10:27:22
-
Characterization and validation of an in vivo confocal Raman spectroscopy led tri‐method approach in the evaluation of the lip barrier
摘要： Background/Aim: It was the aim to establish and validate in vivo confocal Raman spectroscopy for characterization of the lip barrier in conjunction with transepidermal water loss (TEWL) and skin capacitance assessments. For the first time in vivo, barrier-relevant components of the lip (derived, natural moisturizing factors (NMFs) and ceramides are described. Methods: In 32 healthy volunteers, a dental tongue fixation device was inserted to prevent both voluntary and involuntary lip moisturization during measurements. Seventeen individual parameters relating to water, ceramide, and NMF content were assessed via Raman spectroscopy. Additionally, corneometry and TEWL were measured. To give a guidance for the required volunteer group size of future lip barrier studies for all test parameters, coefficients of variation (CV) were calculated and plots showing the required sample size for a given percentage treatment effect. Results: Raman spectroscopy assessed parameters on the lower lip comprehensively characterized the state of the lip barrier. Parameter variability was sufficiently low to corroborate changes in most parameters using relatively small study populations. Conclusions: Lip skin is comparatively well hydrated. Biophysical measurement of the lip barrier function is a challenge, as unconscious licking of the lower lip has to be prevented. In vivo confocal Raman spectroscopy provides insightful parameters for the characterization of the lip barrier and sufficiently low inter-individual variability to assess relatively small parameter changes employing relatively few study subjects. Differences at the molecular level and at a high spatial resolution are detectable, and these insights might provide a breakthrough in the evaluation of lip barrier function and developing solutions for lip care.
关键词： lip skin measurements,closed chamber transepidermal water loss,lip stratum corneum,skin hydration capacitance,Raman spectroscopy
更新于2025-09-12 10:27:22
-
Characterization of TiO2 photoanodes and natural dyes (Allamanda Blanchetti and Allamanda Cathartica) extract as sensitizers for dye-sensitized solar cell applications
摘要： In the present work, Dye-Sensitized Solar Cells (DSSC) were fabricated using fabricated TiO2 photoanodes and natural dyes (Allamanda Blanchetti (AB) and Allamanda Cathartica (AC)) as the sensitizers. Initially, TiO2 nanoparticles were synthesized by sol–gel technique and a thin ?lm of TiO2 was formed on the FTO substrate by Doctor Blade technique. Then, they were annealed at 400, 500, and 600 °C to act as the photoanode. X-ray diffraction analysis shows the prepared samples have tetragonal crystal structure with anatase and rutile phase. The average crystallite size was found to be 10–17 nm when the annealing temperature (TA) was increased from 400 to 600 °C. From UV–DRS analysis, the percentage of re?ectance was found to starts at 315 nm. The bandgap analysis shows the transitions were indirect allowed and the bandgap value decreases from 3.6 to 2.8 eV when the TA increases from 400 to 600 °C. From the optical absorption spectra, the absorption of dye and dye-sensitized TiO2 was found to be in the visible region. From PL analysis, the emission peak intensity of Ti4+ ?) vacancies with TA increases from 400 to 600 °C was noted. FESEM analysis shows the synthesized particles were spherical and from EDS the presence of Ti and O was con?rmed. From FTIR analysis, the functional groups presented in the prepared extracts were con?rmed. The Ef?ciency of DSSC was found to be 1.16 and 0.30% for AB sensitized TiO2 (400 °C) and AC sensitized TiO2 (400 °C) as photoanodes. From Electrochemical Impedance Spectroscopic (EIS) analysis, DSSC with AB + TiO2 shows low charge transfer resistance compared with AC + TiO2.
关键词： TiO2,Bandgap,Electrical measurements,XRD,Natural Dye,DSSC
更新于2025-09-12 10:27:22
-
Spin-orbit-coupled quantum memory of a double quantum dot
摘要： The concept of quantum memory plays an incisive role in the quantum information theory. As confirmed by the several recent rigorous mathematical studies, the quantum memory inmate in the bipartite system ρAB can reduce the uncertainty about part B, after measurements done on part A. In the present work, we extend this concept to systems with a spin-orbit coupling and introduce the notion of spin-orbit quantum memory. We self-consistently explore the Uhlmann fidelity, the pre- and the post-measurement entanglement entropy, and the post-measurement conditional quantum entropy of the system with spin-orbit coupling and show that measurement performed on the spin subsystem decreases the uncertainty of the orbital part. The uncovered effect enhances with the strength of the spin-orbit coupling. We study the concept of macroscopic realism introduced by Leggett and Garg [Phys. Rev. Lett. 54, 857 (1985)] and observe that POVM measurements done on the system under the particular protocol are noninvasive. For the extended system, we perform quantum Monte Carlo calculations and consider the reshuffling of the electron densities due to an external electric field.
关键词： quantum Monte Carlo,spin-orbit coupling,entanglement entropy,POVM measurements,conditional quantum entropy,quantum memory,Uhlmann fidelity
更新于2025-09-12 10:27:22
-
Development of a near-infrared tunable diode laser absorption spectrometer for trace moisture measurements in helium gas
摘要： There is a demand for water vapor or moisture measurement in gas mixture at trace level from industries like combustion studies, semi-conductor industry, environmental studies, cryogenic services, etc. There are few principles, direct or indirect, to measure moisture—each having individual limitations. Among all, the chilled mirror hygrometer is very accurate but response time is poor; therefore, it is suitable for calibration purposes not for online measurement. An instrument based on near-infrared absorption spectroscopy has been developed and discussed in this article. In this instrument, the laser is modulated with both sinusoidal and slower linear scan, split into two beams: an intense one is passed only through air and the other one through air and the absorption cell of 50 cm length. The balanced detection technique is adopted between the two beams called the reference and the measurement channels, respectively, and the difference signal between the two undergoes the 2-f lock-in detection. This method is good for elimination of moisture present in air and any common-mode noise present in both the channels and as well determines the splitting ratio keeping the absorption cell in vacuum. This method also eliminates the 1-f component present in the signal, which causes asymmetry in the two wings of the 2-f absorption spectra. For computation of absorption spectra, it is found that the Hitran database is sufficient to predict for air as the base gas but Exomol should be used in the cases where helium is the base gas. Simulation and experiment both were performed at different concentration and pressures and the results are found in good agreement for the central spectrum with little difference in wings’ peak. The sensitivity of this instrument achieved at 100 mb pressure in the absorption cell for helium as the base gas with refresh rate of 625 Hz is ～17 ppmv and ～4 ppmv for direct and 2-f measurement, respectively. The applicability of the instrument for air as the base gas is also shown in the paper.
关键词： trace moisture measurements,near-infrared,tunable diode laser absorption spectrometer,helium gas
更新于2025-09-12 10:27:22