Broadband absorbers based on resonant acoustic metamaterials often require intricate designs,yet this complexity inherently restricts their bandwidth,robustness,and manufacturability.To overcome these constraints,we p...Broadband absorbers based on resonant acoustic metamaterials often require intricate designs,yet this complexity inherently restricts their bandwidth,robustness,and manufacturability.To overcome these constraints,we present a composite sound-absorbing metamaterial that combines multiple resonance coupling with quality factor modulation,leveraging micro-perforated plates and porous materials.This metamaterial exhibits near-perfect broadband sound absorption across a frequency range spanning from 340 to 3200Hz.In addition,composite metamaterials exhibit greater robustness compared to resonant metamaterials,demonstrating better noise control capabilities in diffuse sound fields.This work uses a new mechanism to revitalize traditional sound-absorbing materials and bring them back to prominence in noise control.We anticipate that this innovative solution will address noise control challenges in demanding environments and provide a reference for further development of soundabsorbing metamaterials.展开更多
We demonstrate a new technique of measuring differential carrier lifetime and linewidth enhancement factor in a semiconductor optical amplifier. In our method, the optical responses and fiber transfer functions of a s...We demonstrate a new technique of measuring differential carrier lifetime and linewidth enhancement factor in a semiconductor optical amplifier. In our method, the optical responses and fiber transfer functions of a self-gain modulated SOA are measured and, from these, values of carrier lifetimes and linewidth enhancement factors are determined for various SOA input optical powers.展开更多
The vacuum-sealed miniature modulated x-ray source （VMMXS） with a hot cathode is fabricated via the single- step brazing process in a vacuum furnace. An experiment following the VMMXS is implemented to present its p...The vacuum-sealed miniature modulated x-ray source （VMMXS） with a hot cathode is fabricated via the single- step brazing process in a vacuum furnace. An experiment following the VMMXS is implemented to present its performances, including the influence of grid electrode potential on x-ray intensities. The modulation type of the grid electrode as a switch is proposed, and its feasibility is successfully demonstrated. It is noteworthy to discover a phenomenon for the first time, to the best of our knowledge, that the high repetition frequency grid pulse of the VMMXS has a significant effect on the x-ray intensity. The probable cause for this new finding is analyzed.展开更多
基金supported by the Local Science and Technology Development Fund Project(Grant No.YDZX20233100004002)the Shanghai 3-year Action Plan(No.GWVI11.1-37)+1 种基金the Shanghai Pilot Program for Basic Research,the National Natural Science Foundation of China(NSFC)(Grant Nos.12404508,12404509,and 124B2087)the Xiaomi Young Talents Program.
文摘Broadband absorbers based on resonant acoustic metamaterials often require intricate designs,yet this complexity inherently restricts their bandwidth,robustness,and manufacturability.To overcome these constraints,we present a composite sound-absorbing metamaterial that combines multiple resonance coupling with quality factor modulation,leveraging micro-perforated plates and porous materials.This metamaterial exhibits near-perfect broadband sound absorption across a frequency range spanning from 340 to 3200Hz.In addition,composite metamaterials exhibit greater robustness compared to resonant metamaterials,demonstrating better noise control capabilities in diffuse sound fields.This work uses a new mechanism to revitalize traditional sound-absorbing materials and bring them back to prominence in noise control.We anticipate that this innovative solution will address noise control challenges in demanding environments and provide a reference for further development of soundabsorbing metamaterials.
文摘We demonstrate a new technique of measuring differential carrier lifetime and linewidth enhancement factor in a semiconductor optical amplifier. In our method, the optical responses and fiber transfer functions of a self-gain modulated SOA are measured and, from these, values of carrier lifetimes and linewidth enhancement factors are determined for various SOA input optical powers.
文摘The vacuum-sealed miniature modulated x-ray source （VMMXS） with a hot cathode is fabricated via the single- step brazing process in a vacuum furnace. An experiment following the VMMXS is implemented to present its performances, including the influence of grid electrode potential on x-ray intensities. The modulation type of the grid electrode as a switch is proposed, and its feasibility is successfully demonstrated. It is noteworthy to discover a phenomenon for the first time, to the best of our knowledge, that the high repetition frequency grid pulse of the VMMXS has a significant effect on the x-ray intensity. The probable cause for this new finding is analyzed.
