Results 81 to 90 of about 10,285 (303)

High‐efficiency broadband power amplifier design via ideal de‐embedding and direct compensation of GaN‐HEMTs parasitics

IET Microwaves, Antennas & Propagation, 2022
In this work, a design approach for broadband high‐efficiency power amplifiers is presented. The proposed technique is based on deductive de‐embedding of the nonlinear parasitics of packaged GaN‐HEMT devices.
Ahmed Sleem Sayed, Hesham Nabil Ahmed, Mohammad Magdi Darwish   +2 more
doaj   +1 more source

Benchmarking Coaxial and Angular Optical Emission Spectroscopy With Recommendations for Reliable Compositional In Situ Monitoring During Laser Powder Bed Fusion

Advanced Materials Technologies, EarlyView.
ABSTRACT Real‐time insight into local chemistry is critical for reliable part quality in additive manufacturing, especially laser powder bed fusion (PBF‑LB/M), where rapid thermal cycles and localized evaporation can undermine part performance. Optical emission spectroscopy (OES) offers non‑intrusive, in situ plume monitoring, but detection geometry ...
Philipp Gabriel, Bastian Jülich, Anna Rosa Ziefuss, Florian Eibl, Stephan Barcikowski   +4 more
wiley   +1 more source

Optimization of A-class power amplifiers in terms of efficiency

Физика волновых процессов и радиотехнические системы
Background. Typical A-class power amplifiers usually have low electronic efficiency values, since their operating conditions do not always correspond to the optimal efficiency mode. The Aim of the article is to optimize the efficiency of an A–class power
Aleksander V. Baranov
doaj   +1 more source

Omnidirectional Ultra‐Broadband Cu/TiO2 Metasurface Absorbers for High‐Efficiency Solar Thermal Conversion and Photothermal Plasmon‐Driven Catalysis

Advanced Optical Materials, EarlyView.
Metasurface shows selective solar–thermal energy conversion with high‐activity solar/laser‐driven chemistry. The breakthrough is co‐designing broadband FP‐cavity + plasmonic LSPR/SLR resonances in an ultra‐thin metamaterial so that it not only harvests the most efficient proportion of solar radiation but also suppresses mid and IR emissivity. Moreover,
Samira Mehrabi, HaoYu Zhang, Narendra Chaulagain, Edgar Acosta, Nazir P. Kherani   +4 more
wiley   +1 more source

Multi-wavelength fiber laser with erbium doped zirconia fiber and semiconductor optical amplifier [PDF]

, 2010
Multi-wavelength hybrid fiber lasers are demonstrated in both ring and linear cavities using a fabricated Erbium-doped Zirconia fiber (EDZF) and semiconductor optical amplifier (SOA) as gain media.
Hamzah, Amirah, Ahmad, Harith, Boyland, A.J., Hamzah, A., Arof, H., Harun, S.W., Yoo, S., Paul, M.C., Pal, M., Bhadra, S.K., Huri, N.A.D., Kalita, M.P., Harun, Sulaiman Wadi, Das, S., Lokman, A., Lokman, Asiah, Pal, Manimala, Arof, Hamzah, Sahu, Jayanta Kumar, Sahu, J.K., Ahmad, H.   +20 more
core  

Spectral Compensation Strategy for Radical‐Induced Dye Degradation in Liquid Crystal Polymer Composites

Advanced Optical Materials, EarlyView.
A spectral compensation strategy is introduced to overcome radical‐induced degradation of dichroic dyes during UV photopolymerization. By incorporating a complementary photochromic liquid‐crystalline dye, broadband optical attenuation is preserved without disrupting photopolymerization, enabling high‐contrast and durable dye‐doped liquid crystal ...
Wei‐Hsien Wu, Li‐Min Chang, Yu‐Hsuan Peng, Hsiu‐Hui Chen, Chun‐Ta Wang   +4 more
wiley   +1 more source

Perspective: Hollow Core Optical Fibres for Ultraviolet and Visible Wavelengths

Advanced Science, EarlyView.
Hollow core optical fibres bypass material constraints that limit optical fibres at ultraviolet and visible wavelengths. However, their challenging fabrication has limited their development, and significant gains in performance remain possible. In this perspective we outline approaches to enable the next generation of fibres for shorter wavelengths ...
Robbie Mears, Kerrianne Harrington, Jonathan C. Knight, William J. Wadsworth, James M. Stone, Tim A. Birks   +5 more
wiley   +1 more source

Parasitic Stimulated Amplification in High-Peak-Power and Diode-Seeded Nanosecond Fiber Amplifiers

IEEE Photonics Journal, 2014
The broadband parasitic amplification in a diode-seeded nanosecond ytterbium-doped fiber laser amplifier system is numerically and experimentally investigated.
C. L. Chang, P. Y. Lai, Y. Y. Li, Y. P. Lai, C. W. Huang, S. H. Chen, Y. W. Lee, S. L. Huang   +7 more
doaj   +1 more source

Photonic Time Crystals and Time‐Varying Electromagnetic Metamatter: A New Direction for Ultrafast Tunable Photonic and Microwave Materials and Devices

Advanced Science, EarlyView.
Photonic time crystals (PTCs) are systems in which electromagnetic parameters are modulated periodically in time, producing momentum bandgaps via temporal scattering rather than spatial Bragg processes. This review examines the theoretical frameworks, modeling, and computational tools for time‐varying media, and summarizes experimental demonstrations ...
Ranjan Kumar Patel, Shriram Ramanathan, Ronald P. Jenkins, Michael J. Carter   +3 more
wiley   +1 more source

Tapered amplifier laser with frequency-shifted feedback

SciPost Physics, 2016
We present a frequency-shifted feedback (FSF) laser based on a tapered amplifier. The laser operates as a coherent broadband source with up to 370GHz spectral width and 2.3us coherence time.
A. Bayerle, S. Tzanova, P. Vlaar, B. Pasquiou, F. Schreck
doaj   +1 more source