Very long wavelength infrared focal plane arrays with 50% cutoff wavelength based on type-Ⅱ In As/GaSb superlattice

A very long wavelength infrared（VLWIR） focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×10^10cm·Hz^1/2·W^-1. The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.

Low Crosstalk Three-Color Infrared Detector by Controlling the Minority Carriers Type of InAs/GaSb Superlattices for Middle-Long and Very-Long Wavelength

We report a type-Ⅱ InAs/GaSb superlattice three-color infrared detector for mid-wave （MW）, long-wave （LW）, and very long-wave （VLW） detections. The detector structure consists of three contacts of NIPIN architecture for MW and LW detections, and hetero-junction NIP architecture for VLW detection. It is found that the spectral crosstalks can be significantly reduced by controlling the minority carriers transport via doping beryllium in the two active regions of NIPIN section. The crosstalk detection at MW, LW, and VLW signals are achieved by selecting the bias voltages on the device. At 77K, the cutoff wavelengths of the three-color detection are 5.3μm （at OmV）, 141μm （at 300mV） and 19μm （at -20mV） with the detectivities of 4.6xlO11 cm.Hzl/ZW-1, 2.3×10^10 cm.Hzl/2W-1, and 1.0×10^10cm.Hzl/2W-1 for MW, LW and VLW. The crosstalks of the MW channel, LW channel, and VLW channel are almost 0, 0.25, and 0.6, respectively.

Equidistant combination wavelength screening and step-by-step phase-out method for the near-infrared spectroscopic analysis of serum urea nitrogen

We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.

Wet etching and passivation of GaSb-based very long wavelength infrared detectors

The etching and passivation processes of very long wavelength infrared(VLWIR)detector based on the InAs/GaSb/AlSb type-II superlattice have been studied.By studying the effect of each component in the citric acid solution(citric acid,phosphoric acid,hydrogen peroxide,deionized water),the best solution ratio is obtained.After comparing different passivation materials such as sulfide+SiO_(2),Al_(2)O_(3),Si_(3)N_(4) and SU8,it is found that SU8 passivation can reduce the dark current of the device to a greater degree.Combining this wet etching and SU8 passivation,the of VLWIR detector with a mesa diameter of 500μm is about 3.6Ω·cm^(2) at 77 K.

Highly-sensitive NO,NO2,and NH3 measurements with an open-multipass cell based on mid-infrared wavelength modulation spectroscopy

A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central frequencies around 1900.0 cm^-1,1600.0 cm^-1,and 1103.4 cm^-1are used for NO,NO2,and NH3detections,respectively,by timedivision multiplex.An open-path multi-pass cell of 60-m optical path length is applied to the instrument for high sensitivity and reducing the response time to less than 1 s.The prototype achieves a sub-ppb detection limit for all the three target gases with an average time of about 100 s.The instrument is installed in the Jiangsu environmental monitoring center to conduct performance tests on ambient air.Continuous 24-hour measurements show good agreement with the results of a reference instrument based on the chemiluminescence technique.

Development of long-wavelength infrared detector and its space-based application requirements

Infrared detection technology has greatly expanded the ability of mankind to study the earth and the universe. In recent years, the demand for long-wavelength infrared detectors is increasing for their advantages in exploring the earth and the universe. A variety of long-wavelength infrared detectors have been made based on thermal resistive effect, photoelectric effect, etc., in the past few decades. Remarkable achievements have been made in infrared materials, device fabrication,readout circuit, and device package. However, high performance long-wavelength infrared detectors, especially those for large format long-wavelength infrared detector focus plane array, are still unsatisfactory. Low noise, high detectivity, and large format long-wavelength infrared detector is necessary to satisfy space-based application requirements.

Influence of the Mode of Wavelength on the Infrared Reflectance and Transmittance in the Fabric

The study and the practical utilization of the infrared inthe textile field is analysed simply.The test method ofthe infrared transmittance(α_T)and the reflectance(α_R)in the fabric is introduced.The test results of aset of polyester/cotton plain fabrlcs show that the infra-red reflecting regulation can be expressed by quasi-co-sine function.The parameters affecting the α_T and α_Rare analysed, α_T decreases according to negative expo-nent function as the weight per square meter of the fab-ric increases,and α_R increases.Both α_T and α_R will in-crease when the mode of wavelength(λ_m) of the infra-red decreases.It can be deduced that the infrared ab-sorptance of the fabric will increase as λ_m increases inthe studied range.

Evaluation of growth characteristics of Aspergillus parasiticus inoculated in different culture media by shortwave infrared(SWIR) hyperspectral imaging

The growth characteristics of Aspergillus parasitic us incubated on two culture media were ex-amined using shortwave infrared(SWIR,1000-2500 nm)hyperspectral imaging(HSI)in this work.HSI images of the A.parasiticus colonies growing on rose bengal medium(RBM)and maize agar medium(MAM)were recorded daily for 6 days.The growth phases of A.parasiticus were indicated through the pixel number and average spectra of colonies.On score plot of the first principal component(PC1)and PC2,four growth zones with varying mycelium densities were identified.Eight characteristic wavelengths(1095,1145,1195,1279,1442,1655,1834 and 1929 nm)were selected from PC1 loading,average spectra of each colony as well as each growth zone.F urthermore,support vector machine(S VM)classifier based on the eight wavelengths was built,and the classification accuracies for the four zones(from outer to inner zones)on the colonies on RBM were 99.77%,9935%,99.75%and 99.60%and 99.77%,9939%,99.31%and 98.22%for colonies on MAM.In addition,a new score plot of PC2 and PC3 was used to differ-entiate the colonies incubated on RBM and MAM for 6 days.Then characteristic wavelengths of 1067,1195,1279,1369,1459,1694,1834 and 1929 nm were selected from the loading of PC2 and PCg.Based on them,a new SVM model was developed to diferentiate colonies on RBM and MAM with accuracy of 100.00%and 9999%,respectively.In conclusion,SWIR hyperspectral image is a powerful tool for evaluation of growth characteristics of A.parasiticus incubated in diferent culture media.

Modulation of the cutoff wavelength in the spectra for solar selective absorbing coating based on high-entropy films

This paper demonstrates an intrinsic modulation of the cutoff wavelength in the spectra for solar selective absorbing coating based on high-entropy films.The(NiCuCrFeSi)N((NCCFS)N)films were deposited by a magnetron sputtering system.Rutherford backscattering spectroscopy analysis confirms the uniform composition and good homogeneity of these high-entropy films.The real and imaginary parts of the permittivity for the(NCCFS)N material are calculated on the basis of the reflectance spectral fitting results.A redshift cutoff wavelength of the reflectance spectrum with increasing nitrogen gas flow rate exists because of the different levels of dispersion when changing nitrogen content.To realize significant solar absorption,the film surface was reconstituted to match its impedance with air by designing a pyramid nanostructure metasurface.Compared with the absorptance of the as-deposited films,the designed metasurface obtains a significant improvement in solar absorption with the absorptance increasing from 0.74 to 0.99.The metasurfaces also show low mid-infrared emissions with thermal emittance that can be as low as 0.06.These results demonstrate a new idea in the design of solar selective absorbing surface with controllable absorptance and low infrared emission for high-efficiency photo-thermal conversion.

Terahertz Generation Using Implanted InGaAs Photomixers and Multi-wavelength Quantum Dot Lasers

We report on a study of terahertz(THz) generation using implanted In Ga As photomixers and multi-wavelength quantum dot lasers. We carry out In Ga As materials growth, optical characterization, device design and fabrication, and photomixing experiments. This approach is capable of generating a comb of electromagnetic radiation from microwave to terahertz. For shortening photomixer carrier lifetime, we employ proton implantation into an epitaxial layer of lattice matched In Ga As grown on InP. Under a 1.55 μm multimode In GaAs/In GaAsP quantum dot laser excitation, a frequency comb with a constant frequency spacing of 50 GHz generated on the photomixer is measured, which corresponds to the beats of the laser longitudinal modes. The measurement is performed with a Fourier transform infrared spectrometer. This approach affords a convenient method to achieve a broadband multi-peak coherent THz source.

Application of Wavelength Selection Combined with DS Algorithm for Model Transfer between NIR Instruments

This study aims to realize the sharing of near-infrared analysis models of lignin and holocellulose content in pulp wood on two different batches of spectrometers and proposes a combined algorithm of SPA-DS,MCUVE-DS and SiPLS-DS.The Successive Projection Algorithm(SPA),the Monte-Carlo of Uninformative Variable Elimination(MCUVE)and the Synergy Interval Partial Least Squares(SiPLS)algorithms are respectively used to reduce the adverse effects of redundant information in the transmission process of the full spectrum DS algorithm model.These three algorithms can improve model transfer accuracy and efficiency and reduce the manpower and material consumption required for modeling.These results show that the modeling effects of the characteristic wavelengths screened by the SPA,MCUVE and SiPLS algorithms are all greatly improved compared with the full-spectrum modeling,in which the SPA-PLS result in the best prediction with RPDs above 6.5 for both components.The three wavelength selection methods combined with the DS algorithm are used to transfer the models of the two instruments.Among them,the MCUVE combined with the DS algorithm has the best transfer effect.After the model transfer,the RMSEP of lignin is 0.701,and the RMSEP of holocellulose is 0.839,which was improved significantly than the full-spectrum model transfer of 0.759 and 0.918.

Long wavelength interband cascade photodetector with type Ⅱ InAs/GaSb superlattice absorber

We report on a long wavelength interband cascade photodetector with type Ⅱ InAs/GaSb superlattice absorber.The device is a three-stage interband cascade structure.At 77 K,the 50%cutoff wavelength of the detector is 8.48μm and the peak photoresponse wavelength is 7.78μm.The peak responsivity is 0.93 A/W and the detectivity D*is 1.12×10^(11)cm·Hz0.5/W for 7.78μm at-0.20 V.The detector can operate up to about 260 K.At 260 K,the 50%cutoff wavelength is 11.52μm,the peak responsivity is 0.78 A/W and the D*is 5.02×10^(8)cm·Hz0.5/W for the peak wavelength of 10.39μm at-2.75 V.The dark current of the device is dominated by the diffusion current under both a small bias voltage of-0.2 V and a large one of-2.75 V for the temperature range of 120 to 260 K.

新疆白杨河铀矿区白色云母短波红外光谱及电子探针成分特征

铀是我国战略性关键金属资源之一,对科技发展和国家安全具有重要意义。新疆白杨河铀矿床是我国重要的热液型铀矿床,铀成矿过程中广泛发育白色云母。已有研究表明,白杨河铀矿床白色云母短波红外光谱蕴含着丰富的地质信息,记录了其形成热液环境及其与矿化的关系,但其短波红外光谱变化规律及其地质影响因素研究依然薄弱。因此,运用短波红外光谱技术和电子探针微区分析等分析方法对矿床白色云母进行分析研究。研究表明:白杨河铀矿床白色云母Al-OH特征吸收峰波长在2190和2220 nm之间漂移变化,电子探针化学组分表明其发生了明显的Tschermak(契尔马克)替换,Al-OH特征吸收峰波长直接受Mg和Fe含量以及Fe/(Fe+Mg)比值的影响,也受围岩成分的影响。Al-OH特征吸收峰波长较短的白色云母反映了相对高温的热液流体环境,而Al-OH特征吸收峰波长较长的白色云母则代表了相对低温的热液流体环境。白杨河铀矿床铀矿化点附近白色云母具有相对较短的Al-OH特征吸收峰波长、较大的ISM(伊利石光谱成熟度)值和较低的FWHM 2200(半峰宽)值。综合白色云母的Al-OH特征吸收峰波长、ISM值和FWHM2200值的空间变化规律,可以推断白杨河铀矿床的热液矿化中心位于杨庄花岗斑岩与上泥盆统火山岩的北部接触带。这不仅对完善白杨河铀矿床成因和深部与外围勘探具有重要的实际意义,对其他热液型金属矿产勘查亦具有重要的参考价值。

乙纶分子结构及热变性三级长波近红外-中红外光谱研究

长波近红外-中红外(LW-NIR-MIR)光谱开展乙纶分子结构研究。红外模式主要包括:2ν_(asCH3-去卷积-乙纶)、2ν_(asCH2-去卷积-乙纶)、2ν_(sCH3-去卷积-乙纶)、2ν_(sCH2-去卷积-乙纶)、(ν_(asCH2-去卷积-乙纶)+ν_(CH-去卷积-乙纶))、(ν_(asCH2-去卷积-乙纶)+ν_(sCH2-去卷积-乙纶))、ν_(asCH3-去卷积-乙纶)、ν_(sCH3-去卷积-乙纶)、ν_(asCH2-去卷积-乙纶)、ν_(sCH2-去卷积-乙纶)、δ_(CH2-去卷积-乙纶)和ρ_(CH2-去卷积-乙纶)。进一步开展了变温LW-NIR-MIR光谱研究。在303 K~393 K的温度范围内,结构官能团(2ν_(sCH2-去卷积-乙纶),ν_(asCH2-去卷积-乙纶)和ρ_(CH2-去卷积-乙纶))对应频率及强度都有明显改变。最后开展二维LW-NIR-MIR光谱研究。LW-NIR区间,5835 cm^(-1)(2ν_(asCH2-2-二维-乙纶))>5700 cm^(-1)(2ν_(sCH2-二维-乙纶))>5867 cm^(-1)(2ν_(asCH2-1-二维-乙纶))>5800 cm^(-1)(ν_(asCH2-二维-乙纶)+ν_(CH-二维-乙纶))>5762 cm^(-1)(ν_(asCH2-二维-乙纶)+ν_(sCH2-二维-乙纶))>5894 cm^(-1)(2ν_(asCH3-二维-乙纶))。MIR区间,2915 cm^(-1)(ν_(asCH2-二维))>2845 cm^(-1)(ν_(sCH2-二维-乙纶))>2945 cm^(-1)(ν_(asCH3-二维-乙纶))>2885 cm^(-1)(ν_(sCH3-二维-乙纶))。1452 cm^(-1)(δ_(CH2-2-二维-乙纶))>1475 cm^(-1)(δ_(CH2-1-二维-乙纶))。LW-NIR-MIR区间,5835 cm^(-1)(2ν_(asCH2-2-二维-乙纶))>2915 cm^(-1)(ν_(asCH2-二维-乙纶))>2845 cm^(-1)(ν_(sCH2-二维-乙纶))>5894 cm^(-1)(2ν_(asCH3-二维-乙纶))。乙纶分子结构主要官能团对热的敏感程度及变化快慢顺序都存在着较大的差异性。研究拓展了三级LW-NIR-MIR谱在乙纶分子结构及热变性的研究范围。

近红外无创血糖浓度的Label Sensitivity算法和支持向量机回归

近红外光谱分析技术在生物医学工程领域具有广阔应用前景。无创且持续性地测量能实时监控人体血糖水平,给糖尿病患者带来极大便利性、提高生存质量、降低糖尿病并发症发生率具有很大的社会效益。无创血糖监测的想法提出较早,但仍然存在预测精度低、预测值与标签值相关性不高等难点,至今没有达到临床要求。近年来,光谱检测技术发展迅猛且机器学习技术在智能信息处理方面具有明显优势,两者结合可以有效提高人体无创血糖医学监测模型的精度和普适性。提出了一种标签敏感度算法(LS),并结合支持向量机方法建立了人体血糖含量预测模型。使用近红外光谱仪采集了4名志愿者食指处动态血液光谱数据(每名志愿者28组数据),并使用多元散射矫正(MSC)方法消除了部分光散射的影响。考虑血糖对不同波长光的吸收有差异,提出了基于血糖浓度标签差的特征波长挑选方法,并构建了标签敏感度支持向量机(LSSVR)预测模型。设计实验,对比该模型与偏最小二乘回归(PLSR)和区分度支持向量机(FSSVR)算法。结果表明,LS算法的最佳特征波长数为32,经特征波长选择后的LSSVR表现最佳,其均方误差降低至0.02 mmol·L^(-1),明显优于全谱段PLSR模型,血糖浓度的预测值与标签值的相关系数提升至99.8%,预测值全部位于可容许误差的克拉克网格A区内。LSSVR模型的优异表现为早日实现血糖的无创监测提供了新思路。

可见近红外波长标准物质的研制

为拓宽标准物质波段范围,采用物化性能稳定的掺杂有镨钕稀土元素的玻璃作为可见波长的标准物质的原材料,同时采用物化性能稳定的聚苯乙烯片(厚度1 mm)作为近红外波长的标准物质的原材料,利用二者互不影响的特点,并且将其叠加使用会拓展波段范围,由此研制了可见近红外波长标准物质。以F检验法对样品的均匀性进行了检验,用线性拟合法对样品的稳定性进行考察,通过溯源至国家基标准的方式解决了溯源性,确定了标准物质中的波段范围为430 nm~2 550 nm,不确定度为0.1 nm~1.0 nm。弥补了当前标准物质中波段范围覆盖太窄的缺陷。

基于AlAsSb/InAsSb超晶格势垒的InAs/InAsSbⅡ类超晶格nBn中波红外探测器

InAs/InAsSbⅡ类超晶格避免了InAs/GaSbⅡ类超晶格中与Ga原子相关的缺陷复合中心,具有更高的少数载流子寿命,在高工作温度中波红外探测器制备方面有着良好的应用前景。少数载流子单极势垒结构通常被用来抑制探测器暗电流,如nBn结构探测器。在InAs/InAsSbⅡ类超晶格nBn中波红外光电探测器中,势垒层常采用AlAsSb等多元合金材料,阻挡多数载流子的输运。然而,势垒层与吸收层存在的价带偏移(VBO)使得光电流往往需要在大偏压下饱和,从而增大了探测器暗电流。本文设计了一种AlAsSb/InAsSb超晶格势垒,旨在消除VBO并降低量子效率对偏压的依赖性。研究结果显示,150 K下,设计制备的nBn光电探测器的50%截止波长为4.5μm,探测器光响应在-50 mV的小反向偏压下达到了饱和,3.82μm处的峰值响应度为1.82 A/W,对应量子效率为58.8%。在150 K和-50 mV偏压下,探测器的暗电流密度为2.01×10^(-5)A/cm^(2),计算得到在3.82μm的峰值探测率为6.47×10^(11)cm·Hz^(1/2)/W。

基于近红外光谱法的精米品种判别优化研究

由于地理标志性大米巨大的市场价值,导致掺假行为时有发生。因此,为保证地理标志性大米品牌效益和消费者权益,实现准确的精米品种判别具有重要意义。近红外光谱法是精米品种判别的常用方法,通过提取不同品种近红外光谱中的差异性特征实现品种分类。然而,现有研究中存在特征波长选取性能不足和针对指定品种判别准确度不足的问题,限制了基于近红外光谱法的精米品种判别准确度的提升。针对上述问题,面向东北地区五常、响水、越光、银水四种大米,从特征波长选取和品种判别策略两个方面,研究基于近红外光谱法的精米品种判别优化。首先,为提高特征波长选取性能,将排列熵和自适应滑动窗口分割相结合,提出了基于自适应滑动排列熵的精米光谱特征波长选取方法,并开展与传统特征波长选取算法的对比实验。其次,为提高面向不同指定品种的判别准确度,提出基于判别目标的精米品种判别策略,通过研究光谱预处理算法与分类建模算法匹配优化,建立“指定品种-选定模型-选定算法的”的判别流程。实验结果表明,采用所提出的自适应滑动排列熵算法进行特征波长选取,相比于传统算法精米品种判别误差至少可降低50%;采用所提出的基于判别目标的精米品种判别策略,相比于传统的基于固定模型的判别策略的判别准确度至少可提高2.5%。

动力型红外诱饵辐射特性建模及计算研究

建立了动力型红外诱饵能量和辐射特性的数学模型。以AP-PTFE-Mg-Al为装药的动力型红外诱饵为例,进行了具体的计算和分析,得到该动力型红外诱饵药剂的燃烧热和喷管出口处的温度以及由温度引起的辐射峰值波长,获得了不同波长范围的辐射强度。结果表明,该动力型红外诱饵具有较高的能量,短波的辐射强度较高,长波的辐射强度较低。研究所得结论可为动力型红外诱饵的设计提供参考。

基于SWCSS-CARS算法的综纤维素近红外分析模型传递

纸浆材综纤维素的近红外快速无损检测是提高造纸工业智能制造水平的重要手段之一。然而,在实际应用中已有的近红外模型往往无法预测不同仪器测得的木材样品光谱,从而大大限制了该技术的广泛应用。为了降低重新建模和维护的成本,需要运用模型转移技术。笔者以实现纸浆材综纤维素含量近红外分析模型在3台棱光光谱仪器上的共享为目标,以在3台同型号的近红外光谱仪采集的纸浆材样本为研究对象,采用竞争性自适应重加权采样(CARS)波长优化算法,减少筛选稳定一致性波长(SWCSS)方法中无效波长的不利影响,以提高模型对2台从机测量样品的分析能力。建立基于SWCSS-CARS算法的偏最小二乘回归(PLSR)模型,并将其对从机样品的分析能力与单独的SWCSS和CARS的分析能力进行对比分析。结果表明,以综纤维素为基础的SWCSS-CARS方法选出的30个波长建立的主机模型对2台从机样品分析的RPD均大于4.6,Akaike信息准则(A IC)的值为67.68,远远小于模型传递前的3209.83和SWCSS算法的942.82,降低了光谱矩阵的维数,显著提高了模型传递效率。表明SWCSS-CARS算法能够有效去除SWCSS方法中的无效波长,实现了纸浆材综纤维素含量模型在3台同型号近红外光谱仪间的共享。