Resolution and bandwidth are critical for cavity-enhanced dual-comb spectroscopy(CE-DCS). Here, we pioneer an adaptive approach in CE-DCS to improve the broadband as well as the resolution. Postcorrections to dualcomb...Resolution and bandwidth are critical for cavity-enhanced dual-comb spectroscopy(CE-DCS). Here, we pioneer an adaptive approach in CE-DCS to improve the broadband as well as the resolution. Postcorrections to dualcomb interferograms adaptively compensate the relative phase jitters of the optical frequency combs and result in both a mode-resolved spectral resolution and a signal-to-noise ratio of 440:1 in 1 s. Meanwhile, an adaptive combcavity locking scheme exploits more than 90% of the comb modes, covering 340 cm-1(10 THz) at 6450 cm-1. For a single dual-comb interferogram, more than 40,000 comb teeth spaced by 250 MHz are measured in less than7.5 ms, contributing to a noise equivalent absorption per spectral element of 2 × 10-10 cm-1·Hz-1∕2. This adaptive cavity-enhanced dual-comb spectroscopy technique provides an attractive spectroscopic tool that may be utilized in trace-gas sensing, breath and cancer analysis, and engine combustion diagnosis.展开更多
Dual-comb spectroscopy(DCS)is an emerging spectroscopic tool with the potential to simultaneously achieve a broad spectral coverage and ultrahigh spectral resolution with rapid data acquisition.However,the need for tw...Dual-comb spectroscopy(DCS)is an emerging spectroscopic tool with the potential to simultaneously achieve a broad spectral coverage and ultrahigh spectral resolution with rapid data acquisition.However,the need for two independently stabilized ultrafast lasers significantly hampers the potential application of DCS.We demonstrate mode-resolved DCS in the THz region based on a free-running singlecavity dual-comb fiber laser with the adaptive sampling method.While the use of a free-running single-cavity dual-comb fiber laser eliminates the need for two mode-locked lasers and their frequency control,the adaptive sampling method strongly prevents the degradation of spectroscopic performance caused by the residual timing jitter in the free-running dual-comb laser.Doppler-limit-approaching absorption features with linewidths down to 25 MHz are investigated for low-pressure acetonitrile/air mixed gas by comb-mode-resolved THz spectroscopy.The successful demonstration clearly indicates its great potential for the realization of lowcomplexity,Doppler-limited THz spectroscopy instrumentation.展开更多
Optical frequency comb with evenly spaced lines over a broad bandwidth has revolutionized the fields of optical metrology and spectroscopy.Here,we propose a fast interleaved dual-comb spectroscopy with sub-femtometer-...Optical frequency comb with evenly spaced lines over a broad bandwidth has revolutionized the fields of optical metrology and spectroscopy.Here,we propose a fast interleaved dual-comb spectroscopy with sub-femtometer-resolution and absolute frequency,in which two electro-optic frequency combs are swept.Electrically-modulated stabilized laser enables ultrahigh resolution of 0.16 fm(or 20 k Hz in optical frequency)and single-shot measurement in 90 ms.Total 20 million points are recorded spanning 3.2 nm(or 400 GHz)bandwidth,corresponding to a spectral sampling rate of 2.5×10^(8)points/s under Nyquist-limitation.Besides,considering the trade-off between the measurement time and spectral resolution,a fast single-shot measurement is also realized in 1.6 ms with 8 fm(or 1 MHz)resolution.We demonstrate the 25-averaged result with 30.6 d B spectral measurement signal-to-noise ratio(SNR)by reducing the filter bandwidth in demodulation.The results show great prospect for precise measurement with flexibly fast refresh time,high spectral resolution,and high SNR.展开更多
Noninvasive,glucose-monitoring technologies using infrared spectroscopy that have been studied typically require a calibration process that involves blood collection,which renders the methods somewhat invasive.We deve...Noninvasive,glucose-monitoring technologies using infrared spectroscopy that have been studied typically require a calibration process that involves blood collection,which renders the methods somewhat invasive.We develop a truly noninvasive,glucose-monitoring technique using midinfrared spectroscopy that does not require blood collection for calibration by applying domain adaptation(DA)using deep neural networks to train a model that associates blood glucose concentration with mid-infrared spectral data without requiring a training dataset labeled with invasive blood sample measurements.For realizing DA,the distribution of unlabeled spectral data for calibration is considered through adversarial update during training networks for regression to blood glucose concentration.This calibration improved the correlation coeffcient between the true blood glucose concentrations and predicted blood glucose concentrations from 0.38 to 0.47.The result indicates that this calibration technique improves prediction accuracy for mid-infrared glucose measurements without any invasively acquired data.展开更多
From the perspective of error compensation in the sampling process, a digital calibration algorithm was studied for the processing of spectral data in dual-comb spectroscopy. In this algorithm, dynamic adaptation to p...From the perspective of error compensation in the sampling process, a digital calibration algorithm was studied for the processing of spectral data in dual-comb spectroscopy. In this algorithm, dynamic adaptation to phase fluctuations maintained constant measurement results of spectral line positions and intensities. A mode-resolved broadband absorption spectrum was obtained over the full-spectral range of the comb with a Hertz linewidth of radio frequency comb mode.The measured spectrum spanned over 10 THz, which covered the multiplexed absorption regions of mixed gases, such as CO2 and N2 O. The calibrated interferograms were also capable of direct coherent averaging in the time domain. The transmittance obtained deviated from the theoretical calculation by no more than 2% in the whole spectral span.展开更多
The electronic structure of nitrogen trifluoride was investigated by combining the high-resolution electron momentum spectroscopy with the high-level calculations. The experimental binding energy spectra and the momen...The electronic structure of nitrogen trifluoride was investigated by combining the high-resolution electron momentum spectroscopy with the high-level calculations. The experimental binding energy spectra and the momentum distributions of each orbital were compared with the results of Hartree-Fock, density functional theory (DFT), and symmetry-adapted- cluster configuration-interaction (SAC-CI) methods. SAC-CI and DFT-B3LYP with the aug-cc-pVTZ basis set can well reproduce the binding energy spectra and the observed momentum distributions of the valence orbitals except 1 a2 and 4e orbitals. It was found that the calculated momentum distributions using DFT-B3LYP are even better than those using the high-level SAC-CI method.展开更多
面粉吸水率是评价面粉质量和预测面制品加工特性的重要品质性状。面粉吸水率的测定主要参照国际或国家标准利用粉质仪进行,其测定方法费时费力。基于此,提出利用可见近红外光谱分析技术结合多元统计分析进行面粉吸水率快速、无损检测。...面粉吸水率是评价面粉质量和预测面制品加工特性的重要品质性状。面粉吸水率的测定主要参照国际或国家标准利用粉质仪进行,其测定方法费时费力。基于此,提出利用可见近红外光谱分析技术结合多元统计分析进行面粉吸水率快速、无损检测。参照国标法测定150份小麦面粉样品的吸水率,面粉吸水率变幅为53.10%~74.50%。利用可见近红外分析仪采集面粉样品的光谱信息,有效光谱范围为570~1100 nm。采用偏最小二乘回归(PLSR)、主成分回归(PCR)和支持向量机回归(SVR)将光谱信息和面粉吸水率进行关联,分别建立面粉吸水率的定量分析预测模型,筛选最优的建模方法。在优选的建模方法的基础上,采用竞争性自适应重加权(CARS)、区间随机蛙跳(iRF)、迭代保留信息变量(IRIV)和连续投影(SPA)算法提取特征波长,筛选最优的特征波长提取算法。基于最优的建模方法和最优的特征波长提取算法提取的特征波长,采用标准化(NL)、一阶求导(1 st Der)、基线校正(BL)、标准正态变换(SNV)和去趋势化(DT)5种光谱预处理方法对特征波长的光谱进行预处理,筛选最优的光谱预处理方法。结果表明,采用NL光谱预处理方法对CARS算法提取的24个特征波长(仅占原始波长的2.26%)的光谱进行预处理后建立的PLSR模型性能最佳,预测集相关系数(R_(p)^(2))、预测集均方根误差(RMSEP)和预测相对分析误差(RPD)分别为0.8894、1.4585和2.6413。采用CARS算法提取的特征波长所建的模型不仅能提高模型的性能,还很大程度提高模型运算效率、降低仪器制造成本和光谱仪微型化的难度,从而为面粉吸水率可见近红外无损、快速检测研究奠定了基础。展开更多
Analytical chemistry plays an important role in the qualitive and quantitative analysis for molecules in the various circumstances,especially for the high-resolution analysis.The dual-comb spectroscopy(DCS)technology ...Analytical chemistry plays an important role in the qualitive and quantitative analysis for molecules in the various circumstances,especially for the high-resolution analysis.The dual-comb spectroscopy(DCS)technology with the characteristics of high resolution,high sensitivity and instantaneous sampling exhibited a great potential in high-resolution in-situ spectral methods and has been active in the fields of spatial ranging,air composition analysis,reaction monitoring and so on.In this review,we will summarize the principle of DCS according to the different wavelength coverage and overview the applications of DCS in analytical chemistry.展开更多
基金National Natural Science Foundation of China(NSFC)(61775114)
文摘Resolution and bandwidth are critical for cavity-enhanced dual-comb spectroscopy(CE-DCS). Here, we pioneer an adaptive approach in CE-DCS to improve the broadband as well as the resolution. Postcorrections to dualcomb interferograms adaptively compensate the relative phase jitters of the optical frequency combs and result in both a mode-resolved spectral resolution and a signal-to-noise ratio of 440:1 in 1 s. Meanwhile, an adaptive combcavity locking scheme exploits more than 90% of the comb modes, covering 340 cm-1(10 THz) at 6450 cm-1. For a single dual-comb interferogram, more than 40,000 comb teeth spaced by 250 MHz are measured in less than7.5 ms, contributing to a noise equivalent absorption per spectral element of 2 × 10-10 cm-1·Hz-1∕2. This adaptive cavity-enhanced dual-comb spectroscopy technique provides an attractive spectroscopic tool that may be utilized in trace-gas sensing, breath and cancer analysis, and engine combustion diagnosis.
基金The work at Tokushima University was supported by grants for the Exploratory Research for Advanced Technology(ERATO)MINOSHIMA Intelligent Optical Synthesizer(IOS)Project(JPMJER1304)the Japanese Science and Technology Agency+3 种基金a Grant-in-Aid for Scientific Research(A)(19H00871/26246031)the Ministry of Education,Culture,Sports,Science,and Technology of JapanSubsidy for Regional University and Regional Industry Creation,Cabinet Office,Japan.The work at Beihang University was supported by NSFC(61435002/61521091/61675014/61675015)Fundamental Research Funds for the Central Universities.The authors declare no competing financial interests.
文摘Dual-comb spectroscopy(DCS)is an emerging spectroscopic tool with the potential to simultaneously achieve a broad spectral coverage and ultrahigh spectral resolution with rapid data acquisition.However,the need for two independently stabilized ultrafast lasers significantly hampers the potential application of DCS.We demonstrate mode-resolved DCS in the THz region based on a free-running singlecavity dual-comb fiber laser with the adaptive sampling method.While the use of a free-running single-cavity dual-comb fiber laser eliminates the need for two mode-locked lasers and their frequency control,the adaptive sampling method strongly prevents the degradation of spectroscopic performance caused by the residual timing jitter in the free-running dual-comb laser.Doppler-limit-approaching absorption features with linewidths down to 25 MHz are investigated for low-pressure acetonitrile/air mixed gas by comb-mode-resolved THz spectroscopy.The successful demonstration clearly indicates its great potential for the realization of lowcomplexity,Doppler-limited THz spectroscopy instrumentation.
基金funding from National Natural Science Foundation of China(NSFC)under Grant Nos.61775132,61735015,61620106015supported by the Major Key Project of Peng Cheng Laboratory(PCL)。
文摘Optical frequency comb with evenly spaced lines over a broad bandwidth has revolutionized the fields of optical metrology and spectroscopy.Here,we propose a fast interleaved dual-comb spectroscopy with sub-femtometer-resolution and absolute frequency,in which two electro-optic frequency combs are swept.Electrically-modulated stabilized laser enables ultrahigh resolution of 0.16 fm(or 20 k Hz in optical frequency)and single-shot measurement in 90 ms.Total 20 million points are recorded spanning 3.2 nm(or 400 GHz)bandwidth,corresponding to a spectral sampling rate of 2.5×10^(8)points/s under Nyquist-limitation.Besides,considering the trade-off between the measurement time and spectral resolution,a fast single-shot measurement is also realized in 1.6 ms with 8 fm(or 1 MHz)resolution.We demonstrate the 25-averaged result with 30.6 d B spectral measurement signal-to-noise ratio(SNR)by reducing the filter bandwidth in demodulation.The results show great prospect for precise measurement with flexibly fast refresh time,high spectral resolution,and high SNR.
文摘Noninvasive,glucose-monitoring technologies using infrared spectroscopy that have been studied typically require a calibration process that involves blood collection,which renders the methods somewhat invasive.We develop a truly noninvasive,glucose-monitoring technique using midinfrared spectroscopy that does not require blood collection for calibration by applying domain adaptation(DA)using deep neural networks to train a model that associates blood glucose concentration with mid-infrared spectral data without requiring a training dataset labeled with invasive blood sample measurements.For realizing DA,the distribution of unlabeled spectral data for calibration is considered through adversarial update during training networks for regression to blood glucose concentration.This calibration improved the correlation coeffcient between the true blood glucose concentrations and predicted blood glucose concentrations from 0.38 to 0.47.The result indicates that this calibration technique improves prediction accuracy for mid-infrared glucose measurements without any invasively acquired data.
基金Project supported by the National Natural Science Foundation of China(Grant No.61775114)
文摘From the perspective of error compensation in the sampling process, a digital calibration algorithm was studied for the processing of spectral data in dual-comb spectroscopy. In this algorithm, dynamic adaptation to phase fluctuations maintained constant measurement results of spectral line positions and intensities. A mode-resolved broadband absorption spectrum was obtained over the full-spectral range of the comb with a Hertz linewidth of radio frequency comb mode.The measured spectrum spanned over 10 THz, which covered the multiplexed absorption regions of mixed gases, such as CO2 and N2 O. The calibrated interferograms were also capable of direct coherent averaging in the time domain. The transmittance obtained deviated from the theoretical calculation by no more than 2% in the whole spectral span.
基金supported by the National Natural Science Foundation of China(Grant No.11174175)the Tsinghua University Initiative Scientific Research Program,China
文摘The electronic structure of nitrogen trifluoride was investigated by combining the high-resolution electron momentum spectroscopy with the high-level calculations. The experimental binding energy spectra and the momentum distributions of each orbital were compared with the results of Hartree-Fock, density functional theory (DFT), and symmetry-adapted- cluster configuration-interaction (SAC-CI) methods. SAC-CI and DFT-B3LYP with the aug-cc-pVTZ basis set can well reproduce the binding energy spectra and the observed momentum distributions of the valence orbitals except 1 a2 and 4e orbitals. It was found that the calculated momentum distributions using DFT-B3LYP are even better than those using the high-level SAC-CI method.
文摘面粉吸水率是评价面粉质量和预测面制品加工特性的重要品质性状。面粉吸水率的测定主要参照国际或国家标准利用粉质仪进行,其测定方法费时费力。基于此,提出利用可见近红外光谱分析技术结合多元统计分析进行面粉吸水率快速、无损检测。参照国标法测定150份小麦面粉样品的吸水率,面粉吸水率变幅为53.10%~74.50%。利用可见近红外分析仪采集面粉样品的光谱信息,有效光谱范围为570~1100 nm。采用偏最小二乘回归(PLSR)、主成分回归(PCR)和支持向量机回归(SVR)将光谱信息和面粉吸水率进行关联,分别建立面粉吸水率的定量分析预测模型,筛选最优的建模方法。在优选的建模方法的基础上,采用竞争性自适应重加权(CARS)、区间随机蛙跳(iRF)、迭代保留信息变量(IRIV)和连续投影(SPA)算法提取特征波长,筛选最优的特征波长提取算法。基于最优的建模方法和最优的特征波长提取算法提取的特征波长,采用标准化(NL)、一阶求导(1 st Der)、基线校正(BL)、标准正态变换(SNV)和去趋势化(DT)5种光谱预处理方法对特征波长的光谱进行预处理,筛选最优的光谱预处理方法。结果表明,采用NL光谱预处理方法对CARS算法提取的24个特征波长(仅占原始波长的2.26%)的光谱进行预处理后建立的PLSR模型性能最佳,预测集相关系数(R_(p)^(2))、预测集均方根误差(RMSEP)和预测相对分析误差(RPD)分别为0.8894、1.4585和2.6413。采用CARS算法提取的特征波长所建的模型不仅能提高模型的性能,还很大程度提高模型运算效率、降低仪器制造成本和光谱仪微型化的难度,从而为面粉吸水率可见近红外无损、快速检测研究奠定了基础。
基金financially supported by National Natural Science Foundation of China(No.21974030)Medical Engineering Fund of Fudan University(No.XM03211184)。
文摘Analytical chemistry plays an important role in the qualitive and quantitative analysis for molecules in the various circumstances,especially for the high-resolution analysis.The dual-comb spectroscopy(DCS)technology with the characteristics of high resolution,high sensitivity and instantaneous sampling exhibited a great potential in high-resolution in-situ spectral methods and has been active in the fields of spatial ranging,air composition analysis,reaction monitoring and so on.In this review,we will summarize the principle of DCS according to the different wavelength coverage and overview the applications of DCS in analytical chemistry.