光辐射计量基标准是国家计量体系的重要组成部分,是相关量值的溯源源头.光辐射计量正在朝着量值复现量子化、计量基标准量值传递扁平化方向发展. 根据发展趋势,中国计量科学研究院牵头承担了国家重点研发计划"光辐射计量基标准研究"项目(项目编号:2016YFF0200300),在光辐射计量基标准体系中的波长、功率以及它们与时间、空间量组合的量值方面开展研究.项目研究了光辐射测量量子化技术、高稳定度激光波长复现技术、高温固定点黑体辐射技术、光腔衰荡法气体成份测量技术、太赫兹关键参数计量技术.

High temperature in summer is more and more popular nowadays. This kind of unusual weathers come from the climate change due to the greenhouse gas emission. The politicians around the world are talking about the international cooperation to reduce the CO2 emission. Scientists are paying great efforts to find clean energy to replace the current fossil fuels. In this paper, a technology named silicon photonics is introduced which consumes less energy compared to the tradition techniques. The data centers, consuming about 2.5% of the total electricity generation in United States of America, are taken as an example to analyze the reduced CO2 emission. If the proportion of electricity consumption by data centers are assumed to be unchanged for the last 10 years and next 30 years, the total amount of the reduced CO2 emission is predicted to be incredibly 6789.13 million tons for the year from 2021 to 2050. This work shows that the wide application of low-energy-consumption technology can do the substantial contribution to cool down our planet.

In this paper, the Hartmann-Tran profile (HTP) and its asymptotic limits are employed to analyze the experimentally-measured absorption spectra of CO2 gas. The fitted results by multi-spectrum fitting are compared to those from the ordinary line-shape models. The equivalence and computational efficiency of the asymptotic limits of HTP to their ordinary counterparts are studied. The research shows that the parameters of line position ω0, intensity S, pressure broadening coefficient Γ0/p and shifting coefficient Δ0/p by HTP agree well with those from the speed-dependent hard-collision line-shapes. In comparison, the poorly-determined partial-correlation parameter η makes the fitted line-narrowing parameters less reliable.

文中设计了一种基于现场可编程逻辑门阵列(FP GA)芯片的模拟电压信号采集卡.采用锁相环产生2个频率65 MHz、相位相反的时钟,控制2片模数转化芯片交替工作,实现了130 Msps的等效采样率.采集频率为50 kHz、100 kHz、500 kHz和1 MHz的标准正弦信号,与示波器采集的数据比较,波形无失真.利用信号发生器产生10μs的指数衰减信号,采集卡和示波器采集的曲线重合,拟合得到的衰荡时间仅相差0.83％.该采集卡可用于小型化光腔衰荡光谱仪(CRDS)等装置的信号采集.

This article presents an accurate measurement of line parameters for the P-branch of (30012) <- (00001) (C16O2)-C-12 band with rotational quantum number extending to -72. The spectrometer has a temperature stability of below 0.5 mK at 296 K and a cavity leakage of 0.068 mTorr/hour. An optical frequency comb is employed to measure the absolute transition frequencies. The measured data are processed using multi-spectrum fitting method with different line-shape models to retrieve line positions, intensities, and other line-shape parameters. The correlation between Dicke narrowing and speed-dependent broadening is studied. The measured parameters are compared to a series of spectroscopic databases and previously published results. (C) 2021 Elsevier Ltd. All rights reserved.

衰荡光腔受温度影响长度变化使腔内光斑模式改变,影响测量精度,为达到衰荡光腔内温度均匀分布,利用仿真平台,对控温箱体内加热片发热功率进行仿真计算.首先设计控温箱体几何模型,确定热传导模型和边界条件,通过有限元分析初步确定控温箱体内温度分布;然后通过参数化扫描和迭代运算,优化控温箱体温度场分布,得到均匀化温度分布所需的各加热片最佳工作功率.通过测试,控温箱体内最大温差小于0.06℃,沿衰荡光腔方向,温差小于0.002℃,达到±0.0005℃的控温精度,满足衰荡光腔内温度变化小于±0.003℃的精度要求.

In this paper, to reduce the cavity volume of a cavity ring-down spectrometer (CRDS), we propose designing a Z-folding cavity that has an external dimension of 26.1 entX 8.5 em X 1.5 cm and an expanded length of up to 73. 8 cm. In the study, we perform a simulation based on the parallel-Gaussian-beam-transfer-equation to match the laser mode and cavity mode. By adjusting the focal length and position of two convex lenses, we realize mode matching and identify that only the TEMP, mode existes in the cavity. In the experiment, an acousto-optic-modulator is triggered by a digital-delay-generator to switch the laser beam. The feasibility of the Z-folding cavity is verified by the successfully acquiring ring-down signals. By exponentially fitting the experimental data, the ringdown time is determined to be 0.852 mu s, which provides a maximum residual of 0.004 mu W. The fitted ring-down time is consistent with the theoretical calculation result. The Z-folding cavity designed in this paper is compact and can be used in a commercial CRDS setup.

在实际的检测过程中,保障半导体激光器输出波长稳定是至关重要的,而影响该结果的主要因素是半导体激光器的驱动电流和其工作温度.因此设计了一款恒流驱动模块与温度控制模块相结合的高精度、小型化半导体激光器驱动控制系统.主要采用LJD-eWin5L单片机为主控芯片、以TCM-X107为温控模块实现蝶形激光底座的加热或制冷驱动,该驱动根据设定温度值与测得温度值的比较来进行PID参数改进,根据测量温度范围对串联电阻进行改进.结果 显示,在10℃～40℃范围内温度控制误差小于等于0.003℃;恒流驱动设计驱动电流在0～220 mA范围内误差小于±0.003 mA;满足系统对温度稳定性的要求以及恒流驱动的误差精度,实现了对半导体激光器的高精度驱动控制.

为了精密控制分布反馈激光器的温度与电流,采用数字信号处理芯片,设计了分布反馈激光器驱动装置.通过该装置设定激光器温度和电流的参考电压,经数模转换,再通过温度和电流驱动模块,馈入并驱动分布反馈激光器,进行了实验验证.结果表明,40min内温度变化极差与标准差分别不超过5mK和0.7mK,电流变化极差与标准差不超过40μA和6μA;驱动半导体光放大器,关断时间小于1μs,具有良好的瞬间响应特性;该装置具有较高的温度和电流稳定性,流控模块具有良好的瞬态特性,能够精密控制分布反馈激光器的温度和电流.该控制装置可用于光腔衰荡光谱研究,控制分布反馈激光器并驱动光放大器来关断激光.

Fast and high-performance cavity ring-down spectrometer (CRDS) is highly desired to precisely extract spectral parameters. In this paper, we present our comb-assisted Pound-Drever-Hall (PDH) locked CRDS setup, aiming to retrieve molecular parameters. In the setup, a dynamic feedback is used to keep the tight PDH locking even under strong absorption in the spectral measurement. PDH light and probing light enter the ring-down cavity simultaneously under orthogonal polarization, which enables a fast acquisition of ring-down events without interrupting PDH locking. Ultra-stable cavity temperature is realized, which has an accuracy below 0.5 mK in 27 minutes. The optical frequency comb (OFC) system is developed to rapidly and automatically measure the frequency axis with a relatively wide beat-note range. The minimum detectable absorption coefficient and noise-equivalent absorption coefficient (NEA) are 7.6×10-12cm-1 and 5.3×10-12cm-1Hz-1/2, respectively. The spectrometer is implemented to measure CO2 transition and extract line parameters. The uncertainty for line position is evaluated to be 120 kHz. An accuracy of 0.31% for line intensity is beneficial to the precise determination of CO2 content for the purpose of environment protection and other applications.

蝶形半导体激光器驱动电流的稳定性直接决定了其输出波长的稳定性,进而影响检测精度.为了满足气体浓度检测中对激光器输出波长稳定可调的要求,设计了数字与模拟电路混合的恒流驱动电路.以STC90C51为主控芯片数控模块完成扫描键盘、DA转换;模拟电路主要由负反馈运算放大、高精度CMOS管和反馈电阻构成,完成电压到电流的转换,输出至蝶形半导体激光器,实现蝶形半导体激光器恒流驱动.输出电流在0～300 mA范围内连续可调,输出驱动电流误差小于 ±0.003 mA,满足系统对恒流驱动 ±0.005 mA的误差精度要求.

For the spectral absorption curve of cavity ring-down spectroscopy (CRDS), this study uses the MATLAB software and the least-squares algorithm to program six different line-shape fitting algorithms (VP, GP, AVP, AGP, SDVP, and SDAVP algorithms) commonly used for gas absorption spectroscopy and designs interface windows for the parameter setting and fitting result display. The absorption spectrum of the carbon dioxide gas with known concentration is obtained using CRDS. The six aforementioned algorithms arc used to fit the absorption spectrum, and the fitting residuals of six different line-shape fitting algorithms arc compared. The fitting results denote that the fitting curve is almost coincident with the measuring points. The average AVP residual is the largest, which is 3. 1718 x 10(-3), whereas GP and AGP denote the minimum average residual of 1. 3212 x 10(-3). This study verifies the feasibility of the six aforementioned line-shape fitting algorithms with respect to the fitting of gas absorption spectrum. The AVP' s operation time is the shortest (i.. e., 1. 7516 s), whereas the SDAVP' s operation time is the longest (i.e., 389.682 s). The GP's operation time is less than that of AGP. Therefore, the GP is most suitable for performing the CRDS spectral line-shape fitting with respect to the residuals and operation time.

光学频率梳具有频谱范围宽、频率稳定等优点,在精密测量领域得到广泛应用.本文介绍了国内外光梳光谱仪的研究现状与技术原理,并在此基础上设计的一套Pound-Derver-Hall(PDH)腔长稳定的光梳光谱仪装置模型,为光梳在气体计量领域的应用研究打下基础.

A temperature control system for ring-down cavity is developed.The temperature control box with silicone heating plate on the inner wall is designed firstly,which the ring-down cavity is placed in.The internal temperature distribution is simulated.The finite element analysis and parametric scanning are carried out to get the optimized distribution and power of the heating plate to ensure the temperature uniformity along the light-transmitting part of the cavity.According to the simulation results,the actual box and heating plate are fabricated.Then,the hardware circuit system including temperature sampling module,control module and drive circuit module are designed with PID control algorithm as the core,and the corresponding control algorithm is developed to precisely control the cavity temperature change.After the precision temperature control system is completed,the standard deviation of the temperature variation along the light-transmitting part of the ring-down cavity is less than 0.01 ℃ in 8 hours.

本文开展衰荡光腔温度控制研究.通过负反馈回路控制控温箱温度,编制软件驱动测温仪,采集腔内测温探头3.5小时内的温度值.稳定性研究中,单点温度变化标准差仅为0.18mK.均匀性研究中,4个位置温度变化标准差在0.5～0.7mK之间,不同位置温度差最大为40mK,腔内温度分布均匀,梯度较小.

光腔衰荡光谱技术依赖于气体分子常数测量气体成份量,有望成为新一代基于自然常数的气体成份量基准方法.本文详细介绍了国内外研究机构对于光腔衰荡光谱法在气体成份量测量领域的研究现状,并在此基础上设计出一套基于Pound-Drever-Hall(PDH)锁频技术的光腔衰荡光谱测量装置,旨在完善目前实物计量标准的局限性.

Detection of systematic errors of the measurement method is a demanding task, since it requires an independent, high-accuracy reference method for comparison. Here, we validate the cavity ring-down spectroscopy (CRDS) in relation to the one-dimensional cavity mode-dispersion spectroscopy (1D-CMDS). The complex line-shape function is used for the first time in the simultaneous analysis of absorptive and dispersive spectra and its potential in accurate line-shape studies is indicated. A new approach providing insensitivity of the 1D-CMDS to the drift of the laser-to-cavity locking point is demonstrated.

The spontaneous emission (SE) of Er3+ embedded in a double slot dielectric structure was studied by a quantum-electrodynamical formalism. The study shows that the slot width and the position of Er3+ in slot structure have a significant effect on the SE. The double slot waveguides were fabricated by embedding two low-index Er/Yb silicate material layers into high-index silicon. The radiative efficiency of Er3+ in the double slot waveguides is found to be higher than that of the single slot waveguide, which is consistent with the theory simulation. The 0.67 dB signal enhancement at 1.53 µm in a 4.6-mm-long slot waveguide was observed pumped by 1476 nm laser. These results show the relevance of our model to study the SE processes in multilayer structures and are important for future realization of silicon-compatible active optical devices.

This paper reports the efforts of suppressing Er ion's second-order cooperative up-conversion (CUC). Er/Yb and Er/Y silicate glass waveguides were fabricated, which have same structure, similar Er concentration and peak emission cross-section. Under same 1480 nm pump power, Er/Yb silicate glass shows 4.7 times weaker visible up-conversion luminescence and four times stronger infrared luminescence than Er/Y silicate glass. Through analyzing the physical mechanism, we found that the energy back transfer from Er to Yb plays a significant role on the luminescence difference, which affects and further suppresses the second-order CUC process in Er/Yb co-doped materials. (C) 2012 Elsevier B.V. All rights reserved.