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Improving the activity of waste concrete recycled powder by a mechanical-microwave combing method
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作者 Henan Shi Huajian Li +3 位作者 Liangshun Li Haoliang Dong Zhen Wang Wenxiao Ji 《Railway Sciences》 2025年第5期625-637,共13页
Purpose–The efficient utilization of recycled concrete powder(RCP)has attracted much attention.To break through the limitation of single activation technology of RCP,this study investigates the effects of a mechanica... Purpose–The efficient utilization of recycled concrete powder(RCP)has attracted much attention.To break through the limitation of single activation technology of RCP,this study investigates the effects of a mechanical-microwave method on the reactivity of RCP.Design/methodology/approach–The mechanical properties,hydration products,and pore structure of RCP-incorporated mortar were evaluated.Findings–The results demonstrate that the combined activation reduces the median particle size of RCP and induces a low-frequency shift in the Si-O-T FT-IR characteristic peaks,signifying depolymerization of the silicate network and formation of highly reactive broken bond sites.Concurrently,decreased Si2p and Al2p binding energies in XPS spectra confirm enhanced surface reactivity.The 28-day strength activity index(SAI)of RCP mortar improved from 65.7(untreated)to 82.2%under optimal activation conditions(90-min ball milling followed by 10-min microwave irradiation),outperforming solely mechanical activation by 3.6–6.1%.Furthermore,combined activation increased chemically bound water content from 22.8 to 33.7%,accompanied by a low-wavenumber shift in FT-IR peaks of hydration products.The total porosity of RCP mortar decreased from 17.2 to 14.6%,indicating a denser pore structure.Originality/value–This study explores the feasibility and potential mechanism of mechanical-microwave activation of RCP,aiming to provide valuable insights for the sustainable development of materials.Using activated RCP in cement-based materials reduces the demand for cement and substantially cuts carbon emissions,thereby making a critical contribution to the construction industry’s green and low-carbon transition. 展开更多
关键词 Recycled concrete powder Mechanical-microwave combing method Strength activity index Hydration products Microstructure
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Single DNA Condensation Induced by Hexammine Cobalt with Molecular Combing
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作者 Gao-ming Hu Yu Lin +2 位作者 Shi-yong Ran Ya n-wei Wang Guang-can Yang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2012年第3期359-364,374,共7页
We investigated the interaction between DNA and hexammine cobalt III [Co(NH3)6]3+ by a simple molecular combing method and dynamic light scattering. The average extension of A- DNA-YOYO-1 complex is found to be 20.... We investigated the interaction between DNA and hexammine cobalt III [Co(NH3)6]3+ by a simple molecular combing method and dynamic light scattering. The average extension of A- DNA-YOYO-1 complex is found to be 20.9μm, about 30% longer than the contour length of the DNA in TE buffer (10 mmol/L Tris, 1 mmol/L EDTA, pH=8.0), due to bis-intercalation of YOYO-1. A multivalent cation, hexammine cobalt, is used for DNA condensation. We find that the length of DNA-[Co(NH3)6]3+ complexes decrease from 20.9 μm to 5.9μm as the concentration of the [Co(NH3)6]3+ vary from 0 to 3 μmol/L. This observation provides a direct visualization of single DNA condensation induced by hexammine cobalt. The results from the molecular combing studies are supported by dynamic light scattering investigation, where the average hydrodynamic radius of the DNA complex decreases from 203.8 nm to 39.26 nm under the same conditions. It shows that the molecular combing method is feasible for quantitative conformation characterization of single bio-macromolecules. 展开更多
关键词 Molecular combing Hexammine cobalt CONDENSATION Dynamic light scatter-ing Fluorescent microscopy
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THE INFLUENCE OF COMBING ROLLER SPEED ON PURE RAMIE NOIL ROTOR YARN QUALITY AND SPINNING PERFORMANCE
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作者 林廷坤 黄秀宝 《Journal of China Textile University(English Edition)》 EI CAS 1994年第2期19-21,25-26,共5页
This paper reports the optimum design of combing roller speed with reference to yielding 6-13 Ne(98.4—45.4 tex) pure ramie noil rotor-spun yarns. The universal rotatable composite design is adopted to get the highly ... This paper reports the optimum design of combing roller speed with reference to yielding 6-13 Ne(98.4—45.4 tex) pure ramie noil rotor-spun yarns. The universal rotatable composite design is adopted to get the highly precise regression equations, in which the variables are combing roller speed and yarn linear density considered to be the main technological parameters of combing roller and, the responses are the evaluation indexes concerning spinning stability, fiber length distribution of fibre ring from rotor groove and yarn properties. Based on these regression equations, the contours are plotted to analyse the influences of the parameters on the evaluation indexes; the optimization multicriteria mathematical model is simultaneously established to obtain the optimum parameters with the aid of Object Programming Approach along with Constrained Random Ray Method. Finally, an experiment is carried out to further test the acceptance of the calculated optimum values. It is shown that, for any yarn linear density within 6—13 Ne (98.4—45.4 tex), combing roller speed varying from 5000 to 9150 r/min affects content of extra-long fibre in fibre ring from rotor groove and yarn properties but does not significantly influence spinning stability; 7075 r/min, at which the SAQ-12 type of saw-toothed combing roller runs, is recommended to be the optimum combing roller speed for producing 6—13 Ne (98.4—45.4 tex) pure ramie noil yarns, where a compromise is achieved among the lowest content of extra-long fibre in fibre ring, the best spinning stability and the best yarn properties. 展开更多
关键词 ramie combing ROLLERS RAMIE noil rotor spinning TECHNOLOGICAL parameters optimum design.
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FUZZY DECISION-MAKING OF COMBING ROLLER COVERING FOR SPINNING PURE RAMIE NOIL ROTOR-SPUN YARNS
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作者 黄秀宝 林廷坤 《Journal of China Textile University(English Edition)》 EI CAS 1993年第1期1-9,共9页
This paper deals with the types and specifications of combing roller covering for spinning pureramie noil rotor-spun yarns.A handling mode combining Fuzzy Decision-making and FuzzyCluster Analysis has been used for an... This paper deals with the types and specifications of combing roller covering for spinning pureramie noil rotor-spun yarns.A handling mode combining Fuzzy Decision-making and FuzzyCluster Analysis has been used for analyzing the experimental results.It is shown that,with regard to the specifications of the sawtooth clothing of the combing rol-ler,large working angle,large tooth pitch,fine tooth shape,short tooth height,smooth finish andgood wearability are of benefit to improving the spinning stability and the spun yarn properties.The pinned combing roller,however,regardless of its complicated process of production,is sug-gested to be preferred for spinning the pure ramie noil rotor-spun yarns.The handling mode used in this work is efficient in improving the reliability and objectivity ofthe conclusions and can be used for solving the similar problems. 展开更多
关键词 RAMIE combing ROLLERS metallic clothing FUZZY decision FUZZY cluster analysis RAMIE NOIL rotor SPINNING
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White Shark&Brujas:A century of dedication to carding technology
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《China Textile》 2025年第5期37-37,共1页
Operating out of Shanghai,Brujas Textile Tech(Shanghai)Co.,Ltd.(“Brujas”)is a wholly owned subsidiary of Guangshan White Shark Card Clothing Co.,Ltd.(“White Shark”)tasked with providing international trade service... Operating out of Shanghai,Brujas Textile Tech(Shanghai)Co.,Ltd.(“Brujas”)is a wholly owned subsidiary of Guangshan White Shark Card Clothing Co.,Ltd.(“White Shark”)tasked with providing international trade services to support its parent company's global operations.Whereas White Shark,as the parent company founded in 1962,is the manufacture facilities located in Xinyang,Henan Province.Brujas was founded in 1908 by the Brujas family in Terrassa,Spain.In 2008,White Shark integrated Brujas brand into its production and added European experience and knowledge that continues in the production today.This enables White Shark and Brujas to provide customers with the best,personalized carding solutions.White Shark and Brujas service 8700 clients in over 40 countries globally.The main products of the company include but not limited to:metallic card clothing,flat tops,stationary flat,circular comb,combing roller,cleaning fillet,raising fillet,flexible fillet etc.,and they are widely used in the areas of cotton spinning,non-woven materials,wool and linen spinning. 展开更多
关键词 circular comb stationary flat carding technology international trade services metallic card clothing combing roller wholly owned subsidiary white sharkas
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国密算法SM9的计算性能改进方法 被引量:4
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作者 谢振杰 刘奕明 +1 位作者 罗友强 尹小康 《信息安全研究》 北大核心 2025年第1期5-11,共7页
针对国密算法SM9的计算性能改进问题,提出2维Comb固定基模幂算法、预计算标量乘的拓展应用、针对常用ID优化等计算性能改进方法,理论分析和实验测试表明,所提方法通过预计算并增加可以接受的存储开销,能有效提升固定底数模幂、SM9算法3... 针对国密算法SM9的计算性能改进问题,提出2维Comb固定基模幂算法、预计算标量乘的拓展应用、针对常用ID优化等计算性能改进方法,理论分析和实验测试表明,所提方法通过预计算并增加可以接受的存储开销,能有效提升固定底数模幂、SM9算法3个常见步骤等组件的计算性能.综合运用上述改进方法后,SM9数字签名的生成与验证、密钥交换、密钥封装、加密5项算法的性能提升幅度为14%~116%. 展开更多
关键词 国密算法 SM9 计算性能 预计算 Comb固定基
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Controlling coupled magnons with pumps
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作者 Fan Yang Chenxiao Wang +7 位作者 Zhijian Chen Kaixin Zhao Weihao Liu Shuhuan Ma Chunke Wei Jiantao Song Jinwei Rao Bimu Yao 《Chinese Physics B》 2025年第10期39-53,共15页
Strong coupling effects in magnonic systems are highly promising.They combine the advantages of different quasiparticles and enable energy transfer for coherent information processing.When driven by microwave,electric... Strong coupling effects in magnonic systems are highly promising.They combine the advantages of different quasiparticles and enable energy transfer for coherent information processing.When driven by microwave,electric,or optical pumps,these coupling effects can give rise to intriguing nonlinear phenomena,which have become a focal point in the field of magnonics.This review systematically explores pump-engineered magnon-coupling systems from three perspectives:(1)pump-induced hybridization of magnon modes,(2)nonlinear manipulation of magnon dynamics,and(3)implementation of functional magnonic devices.Unlike conventional cavity-magnon interactions that are constrained by electromagnetic boundaries,pumped coupled magnons are liberated from these restrictions.They can operate over a broad frequency band rather than being confined to discrete modes.An example is the recently discovered pump-induced magnon mode(PIM).These magnons arise from the collective excitations of unsaturated spins driven by microwave pumps.They exhibit reduced damping and photon-number-sensitive splitting characteristics,facilitating waveform-controlled coupling strength and enhanced nonlinearity—features that support phenomena such as magnonic frequency combs(MFCs).By expanding this principle to electric pumping schemes,we bridge fundamental physics and practical device applications,enabling nonreciprocal switching and meter-scale strong coupling.These advances establish high-dimensional control capabilities for coupled magnonics and pave the way for their use as a promising platform for dynamically programmable devices,magnetic-field sensing,and coherent networks. 展开更多
关键词 MAGNON strong coupling magnonic frequency comb SPINTRONICS
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Directly tunable magnon frequency comb effect based on domain wall
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作者 Xiaoxue Yang Huiting Li +4 位作者 Xue-Feng Zhang Xiao-Ping Ma Je-Ho Shim Yingjiu Jin Hong-Guang Piao 《Chinese Physics B》 2025年第10期108-115,共8页
Magnon frequency combs have garnered significant attention due to their wide-ranging potential applications,primarily generated by the interplay between spin waves and oscillating magnetic textures.Developing an easil... Magnon frequency combs have garnered significant attention due to their wide-ranging potential applications,primarily generated by the interplay between spin waves and oscillating magnetic textures.Developing an easily achievable magnon frequency comb with directly tunable comb spacing is pivotal for broadening its utility.In this study,we engineered a Bloch-type magnetic domain wall with a stable structure and fixed position by employing a dual-pinning approach utilizing artificial structural defects and stray fields.We established a magnetic domain wall oscillation mode based on resonant Larmor precession,serving as the foundation for a magnon frequency comb derived from magnetic domain walls.By leveraging the locally distributed Oersted field generated by an alternating current,we achieved precise control over the oscillation frequency of the domain wall,thereby realizing a magnon frequency comb with directly tunable comb spacing.The insights from this research offer a promising shortcut for exploring frequency combs based on the interaction between spin waves and magnetic domain walls. 展开更多
关键词 SPINTRONICS magnetic domain wall spin waves frequency comb
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Ultra-rapid broadband mid-infrared spectral tuning and sensing
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作者 Xiaoshuai Ma Tianjian Lv +3 位作者 Dongxu Zhu Zhuoren Wan Ming Yan Heping Zeng 《Advanced Photonics Nexus》 2025年第3期92-99,共8页
Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting the... Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting their utility in dynamic scenarios such as real-time characterization of multiple molecular absorption bands.We present a high-speed approach for broadband wavelength sweeping in the mid-infrared region,leveraging spectral focusing via difference-frequency generation between a chirped fiber laser and an asynchronous,frequency-modulated electro-optic comb.This method enables pulse-to-pulse spectral tuning at a speed of 5.6 THz∕μs with 380 elements.Applied to spectroscopic sensing,our technique achieves broad spectral coverage(2600 to 3780 cm−1)with moderate spectral resolution(8 cm−1)and rapid acquisition time(-6.3μs).Notably,the controllable electro-optic comb facilitates high scan rates of up to 2 Mscans∕s across the full spectral range(corresponding to a speed of 60 THz∕μs),with trade-offs in number of elements(-30)and spectral point spacing or resolution(33 cm−1).Nevertheless,these capabilities make our platform highly promising for applications such as flow cytometry,chemical reaction monitoring,and mid-infrared ranging and imaging. 展开更多
关键词 tunable mid-infrared lasers broadband spectral sensing spectral focusing electro-optic comb
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Multipartite entanglement and one-way steering in magnon frequency comb
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作者 Qianjun Zheng Yunshan Cao Peng Yan 《Chinese Physics B》 2025年第10期124-132,共9页
We theoretically demonstrate that multipartite entanglement and one-way Einstein-Podolsky-Rosen(EPR)steering in a magnon frequency comb(MFC)can be generated in a hybrid magnon-skyrmion system.When the system is driven... We theoretically demonstrate that multipartite entanglement and one-way Einstein-Podolsky-Rosen(EPR)steering in a magnon frequency comb(MFC)can be generated in a hybrid magnon-skyrmion system.When the system is driven by two microwave fields at the magnonic whispering gallery mode(m WGM)and the skyrmion,the skyrmion can be simultaneously entangled with three magnon modes of the MFC and the entanglement of the first-order magnon pair in the MFC also appears.The results show that the perfect one-way steering between the skyrmion and the three magnons can be obtained.Interestingly,the steering direction can be manipulated by controlling the amplitudes of two drive fields,which provides flexibility in controlling the asymmetry of the EPR steering and may well have practical applications.Moreover,the genuine tripartite entanglement among the skyrmion and the first-order magnon pair can be achieved with appropriate parameters in the steady state.Our work exhibits that the MFC has great potential in preparing multi-mode entanglement resources,with promising applications in quantum communication. 展开更多
关键词 multipartite entanglement one-way steering magnon frequency comb SKYRMION
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Ultrafast and precise distance measurement via real-time chirped pulse interferometry
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作者 Jiawen Zhi Mingyang Xu +3 位作者 Yang Liu Mengyu Wang Chenggang Shao Hanzhong Wu 《Advanced Photonics Nexus》 2025年第2期118-134,共17页
Laser frequency combs,which are composed of a series of equally spaced coherent frequency components,have triggered revolutionary progress in precision spectroscopy and optical metrology.Length/distance is of fundamen... Laser frequency combs,which are composed of a series of equally spaced coherent frequency components,have triggered revolutionary progress in precision spectroscopy and optical metrology.Length/distance is of fundamental importance in both science and technology.We describe a ranging scheme based on chirped pulse interferometry.In contrast to the traditional spectral interferometry,the local oscillator is strongly chirped which is able to meet the measurement pulses at arbitrary distances,and therefore,the dead zones can be removed.The distances can be precisely determined via two measurement steps based on the time-of-flight method and synthetic wavelength interferometry,respectively.To overcome the speed limitation of the optical spectrum analyzer,the spectrograms are stretched and detected by a fast photodetector and oscilloscope and consequently mapped into the time domain in real time.The experimental results indicate that the measurement uncertainty can be well within±2μm,compared with the reference distance meter.The Allan deviation can reach 0.4μm at 4 ns averaging time and 25 nm at 1μs and can achieve 2 nm at 100μs averaging time.We also measured a spinning disk with grooves of different depths to verify the measurement speed,and the results show that the grooves with about 150 m∕s line speed can be clearly captured.Our method provides a unique combination of non-dead zones,ultrafast measurement speed,high precision and accuracy,large ambiguity range,and only one single comb source.This system could offer a powerful solution for field measurements in practical applications in the future. 展开更多
关键词 absolute distance measurement frequency comb chirped pulse interferometry
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Bound state noise-like pulses generation from composite filtering effects
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作者 CHANG Qingyu ZHANG Caishi 《Optoelectronics Letters》 2025年第3期142-148,共7页
This paper demonstrated the generation of multi-wavelength bound state noise-like pulse(BNLP)in a dispersion-managed composite-filtered fiber laser consisting of nonlinear polarization rotation(NPR)and loop.In the cas... This paper demonstrated the generation of multi-wavelength bound state noise-like pulse(BNLP)in a dispersion-managed composite-filtered fiber laser consisting of nonlinear polarization rotation(NPR)and loop.In the case of BNLP,the generation is caused by the interaction between two noise-like pulses(NLPs)induced by the comb-filtering effect,and bound state level can be artificially controlled in the researches.Our work provides a new method for generating low-coherence pulses and establishes a research idea for the study of the comb-filtering effects. 展开更多
关键词 comb filtering effect nonlinear polarization composite filtering dispersion managed fiber laser bound state level low coherence pulses artificially controlled nonlinear polarization rotation
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Temporal SU(1,1) Interferometer Based on Four- Wave Mixing Time Lens and Its Applications in Ultrafast Time-Frequency Manipulation
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作者 Tianyu Liu Zepeng Liu 《Journal of Electronic Research and Application》 2025年第4期327-336,共10页
Temporal optics,which enables lossless manipulation of ultrafast pulses,offers a new dimension for the regulation of quantum optical fields.In this paper,we established a temporal Fourier transform(TF)system based on ... Temporal optics,which enables lossless manipulation of ultrafast pulses,offers a new dimension for the regulation of quantum optical fields.In this paper,we established a temporal Fourier transform(TF)system based on a four-wave mixing(FWM)time lens and constructed a full quantum theoretical model for the resulting temporal SU(1,1)interferometer.This interferometer has high temporal resolution,can impose interference in both time and frequency domains,and is sensitive to the phase derivative.By introducing linear time-varying phase modulation,we achieved sub-picosecond precision in temporal autocorrelation measurements and generatedan optical frequency comb with a fixed interval based on a feedback iteration mechanism.Theoretical analysis revealsthe crucial regulatory role of time-frequency coupling in quantum interference,providing novel solutions for ultrafast quantum imaging,temporal mode encoding,and the generation of optical frequency quantization. 展开更多
关键词 Temporal SU(1 1)interferometer Four-wave mixing time lens Optical frequency comb Temporal optics
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Combing the Globe
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作者 DING WENLEI 《Beijing Review》 2010年第4期32-33,共2页
China’s top comb maker aims to sell its high-end hand-crafted products to overseas customers while improving its brand image For some, woodcarving and small carpentry work are hobbies. But for Tan Chuanhua and his ... China’s top comb maker aims to sell its high-end hand-crafted products to overseas customers while improving its brand image For some, woodcarving and small carpentry work are hobbies. But for Tan Chuanhua and his Carpenter Tan comb brand, the woodworking craft has become a deep-rooted moneymaker. The Chongqing-based handcraft wood comb maker raised HK$140 million ($18 mil- 展开更多
关键词 combing the Globe
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Study of the Application of PPG-5-CETETH-20 in Personal Care Rinse-off Product
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作者 Chen Dongzhi Li Zhenzhen Xu Mingli 《China Detergent & Cosmetics》 CAS 2024年第1期39-44,共6页
PPG-5-Ceteth-20 is a multifunction raw material.PPG-5-Ceteth-20 has a wide range of application in skin care and hair care products.The purpose of this study was to evaluate the performance of PPG-5-Ceteth-20.The resu... PPG-5-Ceteth-20 is a multifunction raw material.PPG-5-Ceteth-20 has a wide range of application in skin care and hair care products.The purpose of this study was to evaluate the performance of PPG-5-Ceteth-20.The results shown that PPG-5-Ceteth-20 can improve hair combing,softness and smoothing in the hair care product.In additional,it can improve foam stability and compactness,and it doesn’t affect the transparency of the hair care product. 展开更多
关键词 PPG-5-Ceteth-20 combing SOFTNESS MULTIFUNCTION
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Third-order nonlinear wavelength conversion in chalcogenide glass waveguides towards mid-infrared photonics 被引量:1
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作者 Fengbo Han Jiaxin Gu +7 位作者 Lu Huang Hang Wang Yali Huang Xuecheng Zhou Shaoliang Yu Zhengqian Luo Zhipeng Dong Qingyang Du 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第10期269-274,共6页
The increasing demand in spectroscopy and sensing calls for infrared(mid-IR)light sources.Here,we theoretically investigate nonlinear wavelength conversion of Ge_(28)Sb_(12)Se_(60)chalcogenide glass waveguide in the m... The increasing demand in spectroscopy and sensing calls for infrared(mid-IR)light sources.Here,we theoretically investigate nonlinear wavelength conversion of Ge_(28)Sb_(12)Se_(60)chalcogenide glass waveguide in the mid-IR spectral regime.With waveguide dispersion engineering,we predict generation of over an octave wavelength(2.8μm-5.9μm)tuning range Raman soliton self-frequency shift,over 2.5 octaves wavelength cover range supercontinuum(1.2μm-8.0μm),as well as single soliton Kerr comb generated in suspended Ge_(28)Sb_(12)Se_(60)waveguide.Our findings evidenced that Ge_(28)Sb_(12)Se_(60)chalcogenide glass waveguides can simultaneously satisfy the generation of Raman soliton self-frequency shift,supercontinuum spectrum,and Kerr frequency comb generation through dispersion engineering towards mid-IR on chip. 展开更多
关键词 chalcogenide glass Raman soliton self-frequency shift SUPERCONTINUUM soliton Kerr comb
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Mid-infrared Optical Frequency Comb-based Fourier Transform Spectrometer for Broadband Molecular Spectroscopy 被引量:1
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作者 Feihu Cheng Weixiong Zhao +5 位作者 Bo Fang Nana Yang Shuangshuang Li Weijun Zhang Lunhua Deng Weidong Chen 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2024年第4期471-480,I0093,共11页
Optical frequency combbased Fourier transform spectroscopy has the features of broad spectral bandwidth,high sensitivity,andmultiplexed trace gas detection,which has valuable application potential in the fields of pre... Optical frequency combbased Fourier transform spectroscopy has the features of broad spectral bandwidth,high sensitivity,andmultiplexed trace gas detection,which has valuable application potential in the fields of precision spectroscopy and trace gas detection.Here,we report the development of a mid-infrared Fourier transform spectrometer based on an optical frequency comb combined with a Herriott-type multipass cell.Using this instrument,the broadband absorption spectra of several important molecules,including methane,acetylene,water molecules and nitrous oxide,are measured by near real-time data acquisition in the 2800-3500 cm^(-1)spectral region.The achieved minimum detectable absorption of the instrument is 4.4×10^(-8)cm^(-1)·Hz^(-1/2)per spectral element.Broadband spectra of H_(2)0 are fited using the Voigt profile multispectral fitting technique and the consistency of the concentration inversion is 1%.Our system also enables precise spectroscopic measurements,and it allows the determination of the spectral line positions and upper state constants of N_(2)O in the(0002)-(1000)band,with results in good agreement with those reported by Toth[Appl.Opt.30,5289(1991)]. 展开更多
关键词 Mid-infrared optical frequency comb Multi-pass cell Fourier transform infrared spectrometer
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Experimental study on phase noise of terahertz quantum cascade laser frequency comb and dual-comb sources
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作者 Lulu Zheng Xianglong Bi +4 位作者 Xuhong Ma Guibin Liu Binbin Liu Kang Zhou Hua Li 《Journal of Semiconductors》 EI CAS CSCD 2024年第12期112-118,共7页
Frequency combs with equally spaced frequency lines show great potentials for applications in spectroscopy,imag-ing,communications,and so on.In the terahertz frequency region,the quantum cascade laser(QCL)is an ideal ... Frequency combs with equally spaced frequency lines show great potentials for applications in spectroscopy,imag-ing,communications,and so on.In the terahertz frequency region,the quantum cascade laser(QCL)is an ideal radiation source for frequency comb and dual-comb operation.The systematic evaluation of phase noise characteristics of terahertz QCL frequency comb and dual-comb sources is of great importance for high precision measurements.In this work,we present detailed measurements and analysis of the phase noise characteristics of terahertz QCL frequency comb and dual-comb sources emitting around 4.2 THz with repetition frequencies of~6.2 GHz.The measurement results for the current noise of the direct current(DC)sources(that are used to electrically pump the terahertz QCLs)indicate that at 100 Hz,the current noise for DC-1 and DC-2 is 0.3895 and 0.0982 nA/Hz1/2,respectively.Such levels of current noise can be safely disregarded.The phase noise of radio frequency(RF)generators(that are employed for injection locking and phase locking),intermode beatnotes,and dual-comb signals with and without phase-locked loop(PLL)are all measured and compared.The experimental results show that in the free-running mode,the phase noise of the intermode beatnote signals is always lower than that of the dual-comb sig-nals across all frequencies.Additionally,the phase noise induced by the RF generators is negligible.By employing the phase lock-ing technique,the phase noise of the intermode beatnote and dual-comb signals in the low offset frequency band can be signifi-cantly suppressed.At an offset frequency of 100 Hz,the measured phase noise values of the dual-comb line without and with phase locking are 15.026 and-64.801 dBc/Hz,respectively. 展开更多
关键词 TERAHERTZ quantum cascade laser frequency comb dual-comb phase noise
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Frequency-modulated continuous-wave multiplexed gas sensingbased on optical frequency comb calibration
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作者 Linhua Jia Xinghua Qu Fumin Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第9期152-163,共12页
Laser absorption spectroscopy has proven to be an effective approach for gas sensing, which plays an important rolein the fields of military, industry, medicine and basic research. This paper presents a multiplexed ga... Laser absorption spectroscopy has proven to be an effective approach for gas sensing, which plays an important rolein the fields of military, industry, medicine and basic research. This paper presents a multiplexed gas sensing system basedon optical frequency comb (OFC) calibrated frequency-modulated continuous-wave (FMCW) tuning nonlinearity. Thesystem can be used for multi-parameter synchronous measurement of gas absorption spectrum and multiplexed opticalpath. Multi-channel parallel detection is realized by combining wavelength division multiplexing (WDM) and frequencydivision multiplexing (FDM) techniques. By introducing nonlinear optical crystals, broadband spectrum detection is simultaneouslyachieved over a bandwidth of hundreds of nanometers. An OFC with ultra-high frequency stability is used asthe frequency calibration source, which guarantees the measurement accuracy. The test samples involve H13C14N, C_(2)H_(2)and Rb vapor cells of varying densities and 5 parallel measurement experiments are designed. The results show that themeasurement accuracies of spectral absorption line and the optical path are 150 MHz and 20 m, respectively. The schemeoffers the advantages of multiplexed, multi-parameter, wide spectrum and high resolution detection, which can realize theidentification of multi-gas components and the high-precision inversion of absorption lines under different environments.The proposed sensor demonstrates great potential in the field of high-resolution absorption spectrum measurement for gassensing applications. 展开更多
关键词 frequency-modulated continuous-wave(FMCW)technology optical frequency comb MULTIPLEXING absorption spectroscopy
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Optical frequency comb technology: from ground to space
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作者 Xiaodong Shao Yu Yan +1 位作者 Hainian Han Zhiyi Wei 《Astronomical Techniques and Instruments》 CSCD 2024年第2期105-116,共12页
Optical frequency combs,as powerful tools for precision spectroscopy and research into optical frequency standards,have driven continuous progress and significant breakthroughs in applications such as time-frequency t... Optical frequency combs,as powerful tools for precision spectroscopy and research into optical frequency standards,have driven continuous progress and significant breakthroughs in applications such as time-frequency transfer,measurement of fundamental physical constants,and high-precision ranging,achieving a series of milestone results in ground-based environments.With the continuous maturation and evolution of femtosecond lasers and related technologies,optical frequency combs are moving from ground-based applications to astronomical and space-based applications,playing an increasingly important role in atomic clocks,exoplanet observations,gravitational wave measurements,and other areas.This paper,focusing on astronomical and space-based applications,reviews research progress on astronomical frequency combs,optical clock time-frequency networks,gravitational waves,dark matter measurement,dual-comb large-scale absolute ranging,and high-resolution atmospheric spectroscopy.With enhanced performance and their gradual application in the field of space-based research,optical frequency combs will undoubtedly provide more powerful support for astronomical science and cosmic exploration in the future. 展开更多
关键词 Optical frequency comb Astronomical comb Optical clock-based time and frequency network Gravitational waves and dark matter Dual-comb ranging
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