光纤光栅半导体激光器激射波长与Bragg波长的偏离

利用包含光纤布拉格光栅(FBG)反射率分布的光纤光栅外腔半导体激光器(FGSL)的理 论模型,对FGSL 的激射波长进行了研究。结果表明激射波长并不一定在FBG布拉格反射波长处;布拉格反射波长相对于激射波长的偏移量与FBG的反射率分布、半导体增益介质的增益谱分布及增益峰值波长有关;激射波长可大于或小于布拉格反射波长。     

基于最小化波长需求的波长路由光网的优化设计

讨论了波长路由光网的资源优化设计问题,提出了一种新的整数线性规划（ILP）公式,用于解决波长通道（WP）和虚波长通道（VWP）的路由选择和波长分配问题,它的优化目标是最小的网络需求,以中国高速信息示范网（CAINONET）为例,分析了波长通道（WP）和虚波长通道（VWP）路由方案之间在波长需求方面的差别,同时还研究了网络波长重用度的问题。     

波长对板料锤击式渐进成形性能的影响

目的研究不同波长对板料锤击式渐进成形性能的影响规律。方法以波长为单一因素,将波长值从0.5~5 mm进行多次重复性实验,分别与普通渐进成形实验结果进行对比。结果波长对材料的成形性有显著影响,锤击式渐进成形波长值在0.5~5 mm时,板料的成形性能均高于普通渐进成形,随着波长的增加,板料的成形性能降低,成形时间减少。结论锤击式渐进成形相对于普通渐进成形在成形性能方面具有优越性,综合考虑成形性能、加工时间和表面质量等因素,板料锤击式渐进成形波长为0.5 mm时,成形性能最好。     

Access to Disparate Soft Matter Materials by Curing with Two Colors of Light

A platform technology for multimaterial photoresists that can be orthogonally cured by disparate colors of light is introduced. The resist's photochemistry is designed such that one wavelength selectively activates the crosslinking of one set of macromolecules, while a different wavelength initiates network formation of a different set of chains. Each wavelength is thus highly selective towards a specific photoligation reaction within the resist. Critically, the shorter wavelength does not induce ligation of the longer wavelength selective species within the same resist mixture, defined as “wavelength orthogonality.” Uniquely, this dual‐color addressable resist system allows generating spatially resolved soft matter materials by simply selecting the curing wavelength, thus constituting a wavelength‐orthogonal multimaterial resist with applications ranging from coatings to 3D additive manufacturing of multimaterial architectures.     

分光光度计波长误差的产生和控制方法

通过对影响分光光度计测量准确性的因素进行分析，认为波长准确度是其中的主要因素。对检定用波长标准进行特性研究，确定各种标准器的用途；对波长误差的构成原理进行分析，确定波长误差的调整方法；综合对检定波长产生误差的相关方面进行论述，全面提出了控制波长误差的具体方法，为控制影响分光光度计测量准确度的波长误差提出了一套解决方案。     

拉线传感器变角度工作条件下的校准

为了解决静强度变形测量试验中,拉线传感器两维角度偏转引入的测量问题,采用转台提供标准偏转角度、拉线传感器正交安装测试的方法,突破了变角度工作条件下的拉线传感器校准技术,提出了基于正交安装的灵敏度系数校准方法,构建了校准装置,并通过两个正交方向的灵敏度系数合成,提出了拉线传感器正交误差模型的建立方法,最终为拉线传感器变角度工作条件下的现场误差测算提供了方案,实现了静强度试验中变形量测量的快速评定。拉线传感器校准方法的探索,对其在测试领域的应用起到了促进作用。     

Temporal sensitivity of the wavelength calibration of a photodiode array spectrometer

Subtle differences in the relationship between wavelength and pixel on photodiode array spectrometers contribute to difficulties in transferring calibrations from one instrument to another and may even introduce errors on a single instrument over time. To quantify the level of drift that might be expected in photodiode instruments, we calibrated the wavelength scale of two Zeiss MMS-1 photodiode spectrometers weekly over a 12-month period. We found no evidence of drift in the wavelength calibration. The wavelength calibration was consistent within 0.03 nm over at least 150 days and better than 0.1 nm over the year. To provide context for the wavelength accuracy, we applied small perturbations to wavelength in two partial least squares (PLS) models. We found that wavelength perturbations introduced a linear increase in bias of about 7%/nm (for example, a 1-nm perturbation shifted fruit dry matter prediction from 14% to 21%) in a kiwifruit dry-matter model and about 3.6 °C/nm in an Intralipid temperature model. By including small wavelength perturbations in the training sets, we were able to reduce this error to less than 1.7%/nm and 0.2 °C/nm in the dry-matter and temperature models, respectively. These results suggest that the wavelength scale of photodiode instruments can be very stable. However, in light of the high sensitivity of the PLS models we examined, we recommend testing and, where possible, mitigating the sensitivity of PLS models to small wavelength shifts.     

发光二极管主波长的优化计算方法

从发光二极管主波长的定义出发,比较分析了计算发光二极管主波长的3种方法,并提出了一种优化的计算方法。先将色品图划分为10个区域,再结合线性插值运算,可以减少运算次数、提高寻找速度,简化了求主波长的计算过程,同时使主波长计算结果的精确度优于0．1nm。     

玻璃包装制品成型过程中的CCD 甄别原理及条件

对高温玻璃包装制品和其周围景物的单色辐射特性和CCD 的光谱响应特性进行了分析,可知CCD 对高温玻璃包装制品及其周围景物的辐照响应谱曲线存在交点,该交点为临界波长,且当波长大于临界波长时,高温玻璃包装制品对CCD 的辐照响应大于其周围景物对CCD 的辐照响应。由此可利用大于临界波长部分的辐照响应产生的高温玻璃包装制品与景物图像的灰度差的原理,来甄别高温玻璃包装制品及其边界。同时提出了采用灰度差原理甄别高温玻璃包装制品的条件,其为高温玻璃包装制品图像的灰度值大于其周围所有景物图像的灰度值,且只有临界波长位于CCD 的感光区间内,才能满足高温玻璃包装制品的甄别条件,临界波长越小甄别效果越好。     

液面扫描式超声清洗效果分析

依据波的叠加原理及清洗槽内驻波场形成的特点,对在一个半波长行程内多次改变液面高度的超声清洗效果进行了实验研究。实验中用铝箔空化腐蚀法检验降低λ／4及三次降低λ／8液面高度的超声清洗效果,同时测量了液面高度变化对系统谐振频率的影响。结果表明,利用多次变液面的方法能获得比较均匀的超声清洗效果,且可以通过液面升降对物件进行“扫描”清洗;此外,结果还表明,在一个半波长行程中液面高度的变化对系统谐振频率影响不大,基本在换能器的频带内。     

Effect on the partial least-squares prediction of yarn properties combining raman and infrared measurements and applying wavelength selection

The combination of Raman and infrared spectroscopy on the one hand and wavelength selection on the other hand is used to improve the partial least-squares (PLS) prediction of seven selected yarn properties. These properties are important for on-line quality control during production. From 71 yarn samples, the Raman and infrared spectra are measured and reference methods are used to determine the selected properties. Making separate PLS models for all yarn properties using the Raman and infrared spectra, prior to wavelength selection, reveals that Raman spectroscopy outperforms infrared spectroscopy. If wavelength selection is applied, the PLS prediction error decreases and the correlation coefficient increases for all properties. However, a substantial wavelength selection effect is present for the infrared spectra compared to the Raman spectra. For the infrared spectra, wavelength selection results in PLS prediction errors comparable with the prediction performance of the Raman spectra prior to wavelength selection. Concatenating the Raman and infrared spectra does not enhance the PLS prediction performance, not even after wavelength selection. It is concluded that an infrared spectrometer, combined with a wavelength selection procedure, can be used if no (suitable) Raman instrument is available.     

Color separation of high-density dielectric rectangular grating in the Fresnel diffraction region

A high-density dielectric rectangular grating is designed for color separation in a Fresnel diffraction field. The Fresnel field distribution is analyzed and the optimization conditions for color separation are given. The process of the modes propagating and energy exchanging with the diffraction orders are expressed by modal method. The color separation for different polarizations can be realized. The energy efficiency is 96.3% at the 633 nm wavelength and 86.9% at the 488 mm wavelength for both TE polarizations, while the energy efficiency is theoretically 96.3% at the 633 nm wavelength for TE polarization and 90.6% at the 488 nm wavelength for TM polarization. The field distributions are scanned by the near-field scanning optical microscopy, and the efficiency is 71.2% for the 633 nm wavelength and 67.3% for the 488 nm wavelength for both TE polarizations experimentally.     

外腔激光器实现波长变换的理论及实验

理论上从半导体激光器的速率方程出发,利用其增益饱和效应,提出了光纤光栅外腔半导体激光器实现波长变换的理论模型。利用此模型对入射波为高斯波时的波长变换进行了数值模拟。实验实测了光纤光栅外腔半导体激光器的波长变换前后的谱线,得到带宽 0.1nm,边模抑制比为37.9dB 的激光谱线,并且利用此波长的外腔激光器得到了波长转换间隔为 8nm 的激光谱线。理论分析和实验结果证明,光纤光栅外腔半导体激光器在实现波长变换方面具有很好的线性响应特性。     

Thermal effect on the output transmission of single-core fiber Comb filter

We propose and experimentally demonstrate switchable and tunable transmission characteristics of a single-core comb filter based on thermal operation. Its temperature characteristics are investigated to reveal a shift in the peak wavelength position from 0.15 to 0.41 nm/°C and a tunable range of wavelength spacing of 1.18–1.38 nm for maximum and minimum effective lengths, respectively. This configuration provides the unique advantages of an all-fiber structure, tunable wavelength spacing, switchable spectral peaks, independent tuning of the center wavelength and wavelength spacing of the spectral peaks, and low polarization sensitivity. It is relatively simple to fabricate and is expected to have applications in temperature fiber optic sensors and multiwavelength fiber laser sources.     

Light intensification modeling of coating inclusions irradiated at 351 and 1053 nm

Electric-field modeling provides insight into the laser damage resistance potential of nodular defects. The laser-induced damage threshold for high-reflector coatings is 13x lower at the third harmonic (351 nm) than at the first harmonic (1053 nm) wavelength. Linear and multiphoton absorption increases with decreasing wavelength, leading to a lower-third harmonic laser resistance. Electric-field effects can also be a contributing mechanism to the lower laser resistance with decreasing wavelength. For suitably large inclusions, the nodule behaves as a microlens. The diffraction-limited spot size decreases with wavelength, resulting in an increase in intensity. Comparison of electric-field finite-element simulations illustrates a 3x to 16x greater light intensification at the shorter wavelength.     

宽带可调谐光源瞬时波长测量方法研究

激光波长作为“米”基准的重要实现途径之一，其量值准确性在计量校准、精密测量以及光谱探测等领域具有十分重要的意义。目前基于标准物质吸收谱线的波长基准仅能用于单一波长的计量校准，对于宽带光源波长校准手段有限。本文开展宽带连续调谐激光波长校准技术研究，利用飞秒激光频率梳宽光谱、光频可溯源至原子频率标准、稳定性高的特点，对宽带调谐光源在调谐输出时的连续光波长进行测量，最终实现了1 nm带宽下可调谐激光器调谐输出过程中瞬时值的测量，并利用该结果对可调谐激光器在121 GHz带宽的调频非线性度进行了评价。     

Dominant wavelength sensitivity of thin-film color filters to spectral centering

The dominant wavelength shift of 16 color filters is presented for a ±1% theoretical change in spectral centering and compared with the threshold-perceived color difference (dominant wavelength). The resulting change in dominant wavelength exceeds a threshold limit of a just-noticed color difference for some filters. Spectral-centering tolerance limits are given for the dominant wavelength to be at the threshold limit. The change in dominant wavelength is also presented from normal incidence to 60° angle of incidence, with incidence-angle limits and corresponding f-numbers for optical systems. For comparison, the color difference Δ E*(uv), from the L*u*v* color space, is calculated for each filter for ±1% spectral centering.     

Precise control of the center wavelength of a wavelength-selective single-mode-fiber-thin-film directional coupler

The coupled power and the center wavelength of a wavelength-selective single-mode-fiber-thin-film coupler are accurately determined. The center wavelength depends on the fiber-film spacing. The required remaining cladding thickness of the fiber is accurately obtained from the loss-calibration curve of the half-coupler. The thickness of the film is controlled by spinning speed to match the propagation constants of the fiber and the film. Coupling fiber was used for efficient coupling. Experiments were also carried out for a wavelength filter, and the results almost agree with theoretical values. Shifting of the center wavelength with the condition of fire polishing of the half-coupler is shown.     

两段式DFB半导体激光器波长调谐实验研究

采用国产普通折射率耦合型两段式ＤＦＢ半导体激光器进行了波长调谐实验研究，实验结果表明，通过分别调节激光器两段的工作电流，不仅可以使器件单模工作，而且还能进行波长调谐。波长调谐范围为６．２ｎｍ，连续波长调谐范围为０．９ｎｍ。     

Characteristics of the relation between wavelength and displacement in monochromators with a sine drive

In this paper, we analyze the wavelength variation as the structural parameters of monochromators with a sine drive and describe the procedures for wavelength calibration by the fitting method. It will be helpful to understand and to use the wavelength calibration method in synchrotron radiation beamlines commissioning and other grating scanning spectrometers.