2010_SCG in NL Microstructured Fiber and Recent Advances - Ghosh - INTER. JOURN. OF MICROWAVE AND OP

第41卷第9期激光与红外Vol．41，No．9 2011年9月LASER＆INFRARED September，2011文章编号：1001-5078（2011）09-0969-05·激光应用技术·激光诱导等离子体加工石英微通道的损伤模型李世雄，白忠臣，黄政，张欣，秦水介（贵州大学贵州省光电子技术及应用重点实验室，贵州贵阳550025）摘要：利用调Q的NdʒYAG激光器输出的纳秒激光脉冲诱导等离子体加工石英微通道，加工深度可达4．2mm，通道内壁光滑。

本文对激光脉冲与物质相互作用的移动损伤模型进行了研究，建立了适用于纳秒激光脉冲诱导等离子体加工石英微通道的损伤模型，利用损伤模型分析了通道特点，模型结果与实验结果基本相符。

关键词：激光诱导等离子体；微通道；激光脉冲；损伤模型中图分类号：TN249文献标识码：A DOI：10．3969/j．issn．1001-5078．2011．09．006Breakdown model of micro channels fabrication in fused silicasubstrates by laser-induced plasmaLI Shi-xiong，BAI Zhong-chen，HUANG Zheng，ZHANG Xin，QIN Shui-jie（Key Lab of Photoelectron Technology and Application，Guizhou University，Guiyang550025，China）Abstract：A Q-switched NdʒYAG laser is used to fabricate micro channels in a1cm3fused silica substrate．The workis done by laser-induced plasma．The interior wall of the micro channels is smooth and the depth of the channels is upto4．2mm．The model of moving breakdown induced by laser pulses is set up and analyzed．The model can be used topredict the breakdown of micro channels fabricated by laser-induced plasma with nanosecond NdʒYAG laser pulses．The model can also be used to analyze the channel characteristics．The model conforms to the experimental resultswell．Key words：laser-induced plasma；micro channels；laser pulses；breakdown model1引言微/纳米通道是国内外微纳米技术研究的热点，可应用于DNA分析、血液分析、化学分析、微型电子机械系统等多个方面。

Interlaboratory T est …Microbial barrier testing of packa ging materials for medical devices which are tobe ster ili ze d“according to DIN 58953-6:2010Test re portJanuary 2013Author: Daniel ZahnISEGA Forschungs- und Untersuchungsgesellschaft mbHTest report Page 2 / 15Table of contentsSeite1.General information on the Interlaboratory Test (3)1.1 Organization (3)1.2 Occasion and Objective (3)1.3 Time Schedule (3)1.4 Participants (4)2.Sample material (4)2.1 Sample Description and Execution of the Test (4)2.1.1 Materials for the Analysis of the Germ Proofness under Humidityaccording to DIN 58953-6, section 3 (5)2.1.2 Materials for the Analysis of the Germ Proofness with Air Permeanceaccording to DIN 58953-6, section 4 (5)2.2 Sample Preparation and Despatch (5)2.3 Additional Sample and Re-examination (6)3.Results (6)3.1 Preliminary Remark (6)3.2 Note on the Record of Test Results (6)3.3 Comment on the Statistical Evaluation (6)3.4 Outlier tests (7)3.5 Record of Test Results (7)3.5.1 Record of Test Results Sample F1 (8)3.5.2 Record of Test Results Sample F2 (9)3.5.3 Record of Test Results Sample F3 (10)3.5.4 Record of Test Results Sample L1 (11)3.5.5 Record of Test Results Sample L2 (12)3.5.6 Record of Test Results Sample L3 (13)3.5.7 Record of Test Results Sample L4 (14)4.Overview and Summary (15)Test report Page 3 / 15 1. General Information on the Interlaboratory Test1.1 OrganizationOrganizer of the Interlaboratory Test:Sterile Barrier Association (SBA)Mr. David Harding (director.general@)Pennygate House, St WeonardsHerfordshire HR2 8PT / Great BritainRealization of the Interlaboratory Test:Verein zur Förderung der Forschung und Ausbildung fürFaserstoff- und Verpackungschemie e. V. (VFV)vfv@isega.dePostfach 10 11 0963707 Aschaffenburg / GermanyTechnical support:ISEGA Forschungs- u. Untersuchungsgesellschaft mbHDr. Julia Riedlinger / Mr. Daniel Zahn (info@isega.de)Zeppelinstraße 3 – 563741 Aschaffenburg / Germany1.2 Occasion and ObjectiveIn order to demonstrate compliance with the requirements of the ISO 11607-1:2006 …Packaging for terminally sterilized medical devices -- Part 1: Requirements for materials, sterile barrier systems and packaging systems“ validated test methods are to be preferably utilized.For the confirmation of the microbial barrier properties of porous materials demanded in the ISO 11607-1, the DIN 58953-6:2010 …Sterilization – Sterile supply – Part 6: Microbial barrier testing of packaging materials for medical devices which are to be sterilized“ represents a conclusive method which can be performed without the need for extensive equipment.However, since momentarily no validation data on DIN 58953-6 is at hand concerns emerged that the method may lose importance against validated methods in a revision of the ISO 11607-1 or may even not be considered at all.Within the framework of this interlaboratory test, data on the reproducibility of the results obtained by means of the analysis according to DIN 58953-6 shall be gathered.1.3 Time ScheduleSeptember 2010:The Sterile Barrier Association queried ISEGA Forschungs- und Unter-suchungsgesellschaft about the technical support for the interlaboratory test.For the realization, the Verein zur Förderung der Forschung und Ausbildungfür Faserstoff- und Verpackungschemie e. V. (VFV) was won over.November 2010: Preliminary announcement of the interlaboratory test / Seach for interested laboratoriesTest report Page 4 / 15 January toDecember 2011: Search for suitable sample material / Carrying out of numerous pre-trials on various materialsJanuary 2012:Renewed contact or search for additional interested laboratories, respectively February 2012: Sending out of registration forms / preparation of sample materialMarch 2012: Registration deadline / sample despatchMay / June 2012: Results come in / statistical evaluationJuly 2012: Despatch of samples for the re-examinationSeptember 2012: Results of the re-examination come in / statistical evaluationNovember 2012: Results are sent to the participantsDecember 2012/January 2013: Compilation of the test report1.4 ParticipantsFive different German laboratories participated in the interlaboratory test. In one laboratory, the analyses were performed by two testers working independently so that six valid results overall were received which can be taken into consideration in the evaluation.To ensure an anonymous evaluation of the results, each participant was assigned a laboratory number (laboratory 1 to laboratory 6) in random order, which was disclosed only to the laboratory in question. The complete laboratory number breakdown was known solely by the ISEGA staff supporting the proficiency test.2. Sample Material2.1 Sample Description and Execution of the TestUtmost care in the selection of suitable sample material was taken to include different materials used in the manufacture of packaging for terminally sterilized medical devices.With the help of numerous pre-trials the materials were chosen covering a wide range of results from mostly germ-proof samples to germ permeable materials.Test report Page 5 / 15 2.1.1 Materials for the Analysis of Germ Proofness under Humidity according to DIN 58953-6, section 3:The participants were advised to perform the analysis on the samples according to DIN 58953-6, section 3, and to protocol their findings on the provided result sheets.The only deviation from the norm was that in case of the growth of 1 -5 colony-forming units (in the following abbreviated as CFU) per sample, no re-examination 20 test pieces was performed.2.1.2 Materials for the Analysis of Germ Proofness with Air Permeance according to DIN 58953-6, section 4:The participants were advised to perform the analysis on the samples according to DIN 58953-6, section 4, and to protocol their findings on the provided result sheets.2.2 Sample Preparation and DespatchFor the analysis of the germ proofness under humidity, 10 test pieces in the size of 50 x 50 mm were cut out of each sample and heat-sealed into a sterilization pouch with the side to be tested up.Out of the 10 test pieces, 5 were intended for the testing and one each for the two controls according to DIN 58953-6, sections 3.6.2 and 3.6.3. The rest should remain as replacements (e.g. in case of the dropping of a test piece on the floor etc.).For the analysis of the germ proofness with air permeance, 15 circular test pieces with a diameter of 40 mm were punched out of each sample and heat-sealed into a sterilization pouch with the side to be tested up.Test report Page 6 / 15 Out of the 15 test pieces, 10 were intended for the testing and one each for the two controls according to DIN 58953-6, section 4.9. The rest should remain as replacements (e.g. in case of the dropping of a test piece on the floor etc.).The sterilization pouches with the test pieces were steam-sterilized in an autoclave for 15 minutes at 121 °C and stored in an climatic room at 23 °C and 50 % relative humidity until despatch.2.3 Additional Sample and Re-examinationFor the analysis of the germ proofness under humidity another test round was performed in July / August 2012. For this, an additional sample (sample L4) was sent to the laboratories and analysed (see 2.1.2). The results were considered in the evaluation.For validation or confirmation of non-plausible results, occasional samples for re-examination were sent out to the laboratories. The results of these re-examinations (July / August 2012) were not taken into consideration in the evaluation.3. Results3.1 Preliminary RemarkSince the analysis of germ proofness is designed to be a pass / fail – test, the statistical values and precision data were meant only to serve informative purposes.The evaluation of the materials according to DIN58953-6,sections 3.7and 4.7.6by the laboratories should be the most decisive criterion for the evaluation of reproducibility of the interlaboratory test results. Based on this, the classification of a sample as “sufficiently germ-proof” or “not sufficiently germ-proof” is carried out.3.2 Note on the Record of Test Results:The exact counting of individual CFUs is not possible with the required precision if the values turn out to be very high. Thus, an upper limit of 100 CFU per agar plate or per test pieces, respectively, was defined. Individual values above this limit and values which were stated with “> 100” by the laboratories, are listed as 100 CFU per agar plate or per test piece, respectively, in the evaluation.Test report Page 7 / 153.3 Comment on the Statistical EvaluationThe statistical evaluation was done based on the series of standards DIN ISO 5725-1ff.The arithmetic laboratory mean X i and the laboratory standard deviation s i were calculated from the individual measurement values obtained by the laboratories.The overall mean X of the laboratory means as well as the precision data of the method (reproducibility and repeatability) were determined for each sample3.4 Outlier testsThe Mandel's h-statistics test was utilised as outlier test for differences between the laboratory means of the participants.A laboratory was identified as a “statistical outlier” as soon as an exceedance of Mandel's h test statistic at the 1 % significance level was detected.The respective results of the laboratories identified as outliers were not considered in the statistical evaluation.3.5 Record of Test ResultsOn the following pages, the records of the test results for each interlaboratory test sample with the statistical evaluation and the evaluation according to DIN 58953-6 are compiled.Test report Page 8 / 153.5.1 Record of Test Results Sample F1Individual Measurement values:Statistical Evaluation:Comment:Laboratory 4, as an outlier, has not been taken into consideration in the statistical Evaluation.Outlier criterion: Mandel's h-statistics (1 % level of significance)Overall mean X:91.0CFU / agar plateRepeatability standard deviation s r:17.9CFU / agar plateReproducibility standard deviation s R:19.8CFU / agar plateRepeatability r:50.0CFU / agar plateRepeatability coefficient of variation:19.6%Reproducibility R:55.5CFU / agar plateReproducibility coefficient of variation:21.8%Evaluation according to DIN 58953-6, Section 3.7:Lab. 1 - 6:Number of CFU > 5, i.e. the material is classified as not sufficiently germ-proof.Conclusion:All of the participants, even the Laboratory 4 which was identified as an outlier, came to the same results and would classify the sample material as “not sufficiently germ-proof”Test report Page 9 / 153.5.2 Record of Test Results Sample F2Individual Measurement values:Statistical Evaluation:Comment:Laboratory 4, as an outlier, has not been taken into consideration in the statistical Evaluation.Outlier criterion: Mandel's h-statistics (1 % level of significance)Overall mean X:0CFU / agar plateRepeatability standard deviation s r:0CFU / agar plateReproducibility standard deviation s R:0CFU / agar plateRepeatability r:0CFU / agar plateRepeatability coefficient of variation:0%Reproducibility R:0CFU / agar plateReproducibility coefficient of variation:0%Evaluation according to DIN 58953-6, Section 3.7:Lab. 1 – 3:Number of CFU = 0, i.e. the material is classified as sufficiently germ-proofLab. 4:Number of CFU ≤ 5, i.e. a re-examination on 20 test pieces would have to be done Lab. 5 – 6:Number of CFU = 0, i.e. the material is classified as sufficiently germ-proofConclusion:All of the participants, except for the Laboratory 4 which was identified as an outlier, came to the same results and would classify the sample material as “sufficiently germ-proof”.Test report Page 10 / 153.5.3 Record of Test Results Sample F3Individual Measurement values:Statistical Evaluation:Overall mean X:30.1CFU / agar plateRepeatability standard deviation s r:17.2CFU / agar plateReproducibility standard deviation s R:30.9CFU / agar plateRepeatability r:48.2CFU / agar plateRepeatability coefficient of variation:57.1%Reproducibility R:86.5CFU / agar plateReproducibility coefficient of variation:103%Evaluation according to DIN 58953-6, Section 3.7:Lab. 1 - 4:Number of CFU > 5, i.e. the material is classified as not sufficiently germ-proof. Lab. 5:Number of CFU = 0, i.e. the material is classified as sufficiently germ-proof. Lab. 6:Number of CFU > 5, i.e. the material is classified as not sufficiently germ-proof.Conclusion:Five of the six participants came to the same result and would classify the sample as “not sufficiently germ-proof”. Only laboratory 5 would classify the sample material as “sufficiently germ-proof”.Test report Page 11 / 153.5.4 Record of Test Results Sample L1Individual Measurement values:Statistical Evaluation:Overall mean X:0.09CFU / test pieceRepeatability standard deviation s r:0.32CFU / test pieceReproducibility standard deviation s R:0.33CFU / test pieceRepeatability r:0.91CFU / test pieceRepeatability coefficient of variation:357%Reproducibility R:0.93CFU / test pieceReproducibility coefficient of variation:366%Evaluation according to DIN 58953-6, Section 4.7:Lab. 1 - 6:Number of CFU < 15, i.e. the material is classified as sufficiently germ-proof.Conclusion:All participants came to the same result and would classify the sample as “sufficiently germ-proof”.Test report Page 12 / 153.5.5 Record of Test Results Sample L2Individual Measurement values:Statistical Evaluation:Overall mean X:0.73CFU / test pieceRepeatability standard deviation s r: 1.10CFU / test pieceReproducibility standard deviation s R: 1.18CFU / test pieceRepeatability r: 3.07CFU / test pieceRepeatability coefficient of variation:151%Reproducibility R: 3.32CFU / test pieceReproducibility coefficient of variation:163%Evaluation according to DIN 58953-6, Section 4.7:Lab. 1:Number of CFU > 15, i.e. the material is classified as not sufficiently germ-proof. Lab. 2 - 6:Number of CFU < 15, i.e. the material is classified as sufficiently germ-proof.Conclusion:Five of the six participants came to the same result and would classify the sample as “sufficiently germ-proof”. Only laboratory 1 exceeds the limit value slightly by 1 CFU, so that the sample would be classified as “not sufficiently germ-proof”.Test report Page 13 / 153.5.6 Record of Test Results Sample L3Individual Measurement values:Statistical Evaluation:Overall mean X:0.36CFU / test pieceRepeatability standard deviation s r: 1.00CFU / test pieceReproducibility standard deviation s R: 1.06CFU / test pieceRepeatability r: 2.79CFU / test pieceRepeatability coefficient of variation:274%Reproducibility R: 2.98CFU / test pieceReproducibility coefficient of variation:293%Evaluation according to DIN 58953-6, Section 4.7:Lab. 1 - 6:Number of CFU < 15, i.e. the material is classified as sufficiently germ-proof.Conclusion:All participants came to the same result and would classify the sample as “sufficiently germ-proof”.Test report Page 14 / 153.5.7 Record of Test Results Sample L4Individual Measurement values:Statistical Evaluation:Overall mean X:35.1CFU / test pieceRepeatability standard deviation s r:18.8CFU / test pieceReproducibility standard deviation s R:42.6CFU / test pieceRepeatability r:52.7CFU / test pieceRepeatability coefficient of variation:53.7%Reproducibility R:119CFU / test pieceReproducibility coefficient of variation:122%Evaluation according to DIN 58953-6, Section 4.7:Lab. 1 - 3:Number of CFU > 15, i.e. the material is classified as not sufficiently germ-proof. Lab. 4:Number of CFU < 15, i.e. the material is classified as sufficiently germ-proof. Lab. 5 - 6:Number of CFU > 15, i.e. the material is classified as not sufficiently germ-proof.Conclusion:Five of the six participants came to the same result and would classify the sample as“not sufficiently germ-proof”.Test report Page 15 / 15 4. Overview and SummarySummary:In case of four of the overall seven tested materials, a 100 % consensus was reached regarding the evaluation as“sufficiently germ-proof”and“not sufficiently germ-proof”according to DIN 58 953-6.As for the other three tested materials, there were always 5 concurrent participants out of 6 (83 %). In each case, only one laboratory would have evaluated the sample differently.It is noteworthy that the materials about the evaluation of which a 100 % consensus was reached were the smooth sterilization papers. The differences with one deviating laboratory each occurred with the slightly less homogeneous materials, such as with the creped paper and the nonwoven materials.。

孔胜，安崇伟，徐传豪，郭浩，叶宝云，武碧栋，王晶禹，董军CL⁃20基含能薄膜的微双喷直写成型与性能孔胜1，2，安崇伟1，2，徐传豪1，2，郭浩1，2，叶宝云1，2，武碧栋1，2，王晶禹1，2，董军3（1.中北大学环境与安全工程学院，山西太原030051；2.山西省超细粉体工程技术研究中心，山西太原030051；3.四川省泸州市北方化学工业有限公司，四川泸州646000）摘要：为了获得可在微米尺度下可靠传爆的含能薄膜，以六硝基六氮杂异伍兹烷（CL⁃20）为主体炸药，以乙基纤维素（EC ）和聚叠氮缩水甘油醚（GAP ）为复合黏结体系，选用适量的低沸点溶剂，设计了两种适用于微喷直写工艺的油墨配方，并且采用双喷头微喷直写装置对两种油墨材料进行了直写成型。

采用扫描电子显微镜、MZ⁃220SD 电子密度计、X 射线衍射仪等对成型样品进行了表征，获得了含能薄膜的撞击感度、热分解性能和传爆临界厚度。

结果表明：CL⁃20基含能薄膜表面光滑，内部存在多个微小孔隙，CL⁃20颗粒较小，晶型为ε型，含能薄膜的成型密度为1.547g·cm -3，达到最大理论密度的79.2%。

CL⁃20基含能薄膜的热分解表观活化能为241.21kJ·mol -1，撞击感度特性落高为65.7cm ，临界传爆尺寸为1.0mm×0.045mm 。

关键词：六硝基六氮杂异伍兹烷（CL⁃20）；炸药油墨；含能薄膜；双喷头；微喷直写成型；临界传爆厚度中图分类号：TJ55文献标志码：ADOI ：10.11943/CJEM20200411引言微机电系统（Micro Electronic Mechanical Sys⁃tems ，MEMS ）具有体积小、质量轻、精度高、集成度高、功耗低和批量生产成本低等特点，在火工技术领域具有较好的应用前景［1］。

微尺度传爆药在MEMS 起爆序列中起到承上启下的作用，其传爆性能不仅与装药配方组成关系密切，也与微装药质量息息相关。

焊接热输入对Q690高强钢热影响区组织和韧性的影响李亚江，蒋庆磊，暴一品，王娟，张蕾(山东大学材料液固结构演变与加工教育部重点实验室，济南 250061)摘要：采用不同的热输入焊接淬火-回火态低合金高强钢Q690，研究焊接热输入对接头热影响区的显微组织、精细结构及冲击韧性的影响。

结果表明，当热输入从14 kJ/cm提高到20 kJ/cm时，热影响区冲击韧性先升高再降低。

热输入提高到约16 kJ/cm时，热影响区中下贝氏体的形成可有效限制马氏体的尺寸，细化奥氏体晶粒内的组织并形成许多大角度晶界，有益于提高接头热影响区的冲击韧性；冲击断口纤维区具有韧窝特征，放射区有较大的撕裂台阶。

当热输入较大时，上贝氏体铁素体侧形成的与板条平行的脆性Fe3C条损害了热影响区的塑韧性，冲击断口纤维区的断口具有滑移特征，韧窝数量少，放射区形成小的撕裂刻面。

关键词：高强钢；焊接；热影响区；显微组织；韧性中图分类号：TG457.11 文献标志码：AEffect of heat input on the microstructure and toughness of heat affect zone of Q690 high strength steelLi Yajiang, Jiang Qinglei, Bao Yipin, Wang Juan, Zhang Lei (Key Lab for Liquid-Solid Structural Evolution and Processing of Materials (Ministry ofEducation), Shandong University, Jinan 250061, China)Abstract: High strength low-alloy steel Q690 in quenched and tempered conditions was welded by gas shielded arc welding with different welding heat inputs. The influence of heat input on the microstructure, fine structures and impact toughness of the heat affected zone (HAZ) of the joint was investigated via scanning electron microscope, transmission electron microscopy and Charpy V-notch tests. The results indicated that the optimum impact toughness in HAZ was obtained at the heat input about 16 kJ/cm. The formation of lower bainite effectively restricted the size of martensite laths. The microstructure within austenite grains was refined and many large angle lath boundaries were formed, which contributed to enhancing the impact toughness in HAZ. Fibrous zones in fractured surfaces of impact specimens were characterized by dominant elongated dimples. Large cleavage steps were observed in the radical zone. With the heat input increasing, carbide particles paralleled to the habit planes of bainitic ferrite were formed. These carbide particles are detrimental to the toughness of the joint. Slip bands were shown in the fibrous zone. Coarsen carbides along upper bainitic ferrite held back the formation of dimples. The radical zone was composed of small cleavage facets due to more crack initiation sites provided by carbides.Key words: high strength steel; welding; heat affected zone; microstructure; toughness采用淬火-回火工艺制造的低合金高强钢Q690因其优良的强韧性匹配、高的强度/质量比被广泛应用于采矿设备、工程机械和压力容器等结构的制造。

化工进展Chemical Industry and Engineering Progress2023 年第 42 卷第 S1 期负压状态窄缝通道乙二醇水溶液传热特性赵晨1，苗天泽2，张朝阳3，洪芳军1，汪大海1（1 上海交通大学机械与动力工程学院，上海 200240；2 清华大学先进高功率微波重点实验室，北京100084；3上海交通大学巴黎卓越工程师学院，上海 200240）摘要：高效、紧凑的换热方式需求日益增大，具有高度方向速度梯度大的窄缝通道成为最有前景的方式之一。

本文以质量分数为55%的乙二醇水溶液为工质，针对钛窄缝通道在负压工况进行流动沸腾换热实验。

实验在质量流率750~2000kg/(m 2·s)、饱和温度为80~90℃、入口温度60~70℃的条件下进行。

结果表明，钛需要更高的热流密度激活大量成核点，从而其过冷沸腾起始点（ONB ）前后平均换热系数h 基本不变；质量流量对于ONB 和沸腾充分发展阶段的平均换热系数影响很大；在高过冷度时，沸腾充分发展阶段，钛窄缝通道换热性能对于入口温度不敏感；提高进口温度降低过冷度可以极大提高平均换热系数，70℃条件下平均换热系数在沸腾充分发展阶段可以提高65%；背压对于换热性能的影响主要在沸腾充分发展阶段，背压越低平均换热系数越大。

关键词：微通道；乙二醇水溶液；负压；气液两相流；流动沸腾；传热中图分类号：TK124 文献标志码：A 文章编号：1000-6613（2023）S1-0148-10Heat transfer characteristics of ethylene glycol aqueous solution in slitchannel under negative pressureZHAO Chen 1，MIAO Tianze 2，ZHANG Chaoyang 3，HONG Fangjun 1，WANG Dahai 1(1 School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; 2 Advanced High PowerMicrowave Key Laboratory, Tsinghua University, Beijing 100084, China; 3 Ecole d'ingenieurs Paris, Shanghai Jiao TongUniversity, Shanghai 200240, China)Abstract: The increasing demand for efficient and compact methods of heat transfer has generated interest in the utilization of a narrow channel with a significant velocity gradient along its height, thus presenting substantial potential. This research study focused on investigating the heat transfer phenomena in a flow boiling system that employs a narrow slot channel made of titanium under negative pressure conditions. The experimental analysis employed a designated working fluid, namely an ethylene glycol aqueous solution with a mass concentration of 55%. The experimentation was conducted under specific operational parameters, encompassing a mass flow rate spanning from 750kg/(m²·s) to 2000kg/(m²·s), a saturation temperature within the range of 80℃ to 90℃, and an inlet temperature ranging from 60℃ to 70℃. The findings of the study revealed that the activation of a substantial quantity of nucleation sites in titanium necessitated an elevated heat flux. Consequently, this phenomenon maintained the average heat transfer coefficient (h ) in a state of relative constancy both prior to and subsequent to the onset of nucleate boiling (ONB). The heat flux required to start of ONB and the mean heat transfer coefficient during the研究开发DOI ：10.16085/j.issn.1000-6613.2023-1153收稿日期：2023-07-09；修改稿日期：2023-08-28。

47, 041401 (2010) ©2010 中国激光杂志社 doi: 10.3788/lop47.041401具有金属纳米颗粒结构的微小孔面发射激光器高建霞1 王岭娥1 宋国峰2()12063009; 100083河北理工大学信息学院，河北 唐山中国科学院半导体研究所纳米光电子实验室，北京 摘要 在普通850 nm 垂直腔面发射激光器基础上制备出带有金属纳米颗粒结构的微小孔径垂直腔面发射激光器。

当小孔和金属颗粒的直径分别为400 nm 和100 nm 时，其最大输出光功率达到0.5 mW 。

介绍了该器件的制备工艺，从实验和理论两方面验证了金属纳米颗粒结构激发局域表面等离子体，从而使输出光功率得到提高。

关键词 激光器；局域表面等离子体；金属纳米颗粒；输出光功率；时域有限差分法中图分类号 TN248.4 OCIS 140.39480 160.4236 文献标识码 ANanoaperture Vertical-Cavity Surface-Emitting Laser withMetal Nano-ParticleGao Jianxia 1 Wang Ling ′e 1 Song Guofeng 212 , , , 063009, , , , 100083, ⎛⎞⎜⎜−⎝School of Information Hebei Polytechnic University Tangshan Hebei China Nano Optoelectronics Laboratory Institute of Semiconductors Chinese Academy of Sciences Beijing China ⎟⎟⎠Abstract Nano-aperture vertical-cavity surface-emitting lasers (VCSELs) with metal nano-particle are fabricated based on common 850 nm VCSELs. When the diameters of the aperture and the metal nano-particle are 400 nm and 100 nm respectively, the maximum far-field output power reaches 0.5 mW. The fabrication process is introduced and the output power enhancement due to localized surface plasmon is also analyzed by experiment and theory.Key words lasers; localized surface plasmon; metal nano-particle; output power; finite-different time-domin1 引 言由于受到光学衍射的限制，传统的光存储技术能达到的存储密度有限。

加张烧成改善连续SiC纤维的束丝拉伸性能Improved Tensile Behavior of the Continuous SiC YarnsPyrolyZed from Polycarbosilane under Tension楚增勇,冯春祥,宋永才,王应德,王军,肖加余(国防科技大学新型陶瓷纤维及其复合材料重点实验室,长沙410073DC U Zeng-yong,FENG Chun-iang,SONG Yong-cai,WANG Ying-de,WANG Jun,XIAO Jia-yu(Key Lab of New Ceramic Fibers S Composites,National University of Defense Technology,Changsha410073,China D摘要先驱体法制备连续SiC纤维在烧成过程中有明显的失重和收缩行为,导致纤维在弯曲处应力集中,从而影响其单丝强度和束丝拉伸性能本工作通过施加一定的张力研究加张烧成方式对连续SiC纤维束丝拉伸性能的影响结果表明,通过适当的加张,烧成后的纤维平直,丝间平行程度明显改善,束丝断裂负荷显著增加,可编织性明显加强关键词连续SiC纤维拉伸性能烧成中图分类号T 343.6文献标识码A文章编号1001-4381(2003D06-0036-02Abstract Preparation of polymer-derived SiC fibers involves a pyrolysis process,in which great weight loss and shrinkage are usually recorded.As a result,stress concentrates on the bend portion of the fibers and then lower their tensile strength.To avoid the bend portion and stress concentra-tion,a pyrolysis under tension,as well as their effect on the tensile behavior of SiC yarns was stud-ied.Results revealed that so-obtained SiC fibers are straight and parallel to each other.The crack load of SiC yarns is much increased,or in another word,their weave capability is much improved. Key words continuous SiC fibers tensile behavior pyrolysis先驱体法连续SiC纤维是由聚碳硅烷(Polycar-bosilane,PCS D先驱体经熔纺不熔化烧成而得与C D SiC纤维相比,先驱体法SiC纤维具有直径细,柔顺性好,可编性强的优点,因而其商品已以各种编织体的形式用作耐热材料和复合材料的增强体[1]但先驱丝在无机化的烧成过程中有明显的失重和收缩行为,会导致纤维在弯曲处应力集中,从而影响其单丝强度和束丝拉伸性能,进而影响其可编织性为防止纤维产生小弯,就必须施加一定的张力然而在烧成过程中,单丝强度和束丝承载能力是在显著变化的,具体加张制度文献报道较少,为此,通过理论推导与实验模索,研究了一套行之有效的加张体系[2,3]本研究则着重探讨上述加张烧成过程对连续SiC纤维的束丝拉伸性能的影响实验方法.原料先驱体PCS由本室提供,软化点200 210C,数均分子量1800,为脆性有机硅高聚物[4].2PCS不熔化纤维的制备将PCS置于多孔熔融纺丝机中,在高纯N2保护下,加热至纺丝温度,脱泡处理,于一定压力下经多孔喷丝组件挤出,牵伸成型为连续PCS原纤维[5]将上述原纤维移入预氧化炉中,边鼓风边加热,缓慢升至200C并保温2h,即得Si-反应程度80%,凝胶含量为100%的PCS不熔化纤维.3PCS纤维的加张烧成采用文献[2]中加张装置,通过外置的砝码调节张力大小,在高纯N2的保护下,于石英管式炉中由室温加热至1250C并保温30min,于炉中冷却至室温,便得到具有金属色泽的SiC陶瓷纤维.4SiC纤维拉伸性能测试SiC纤维的单丝强度在YG型强力仪上测得,跨距为25mm取30个数据的平均值作为最终结果SiC纤维束的拉伸曲线在CSC-1101型电子万能试样机上测得测试前纤维束没有上胶,只是用环氧树脂将纤维固定在跨距为25mm的纸框上由仪器配备的电脑采集数据绘制拉伸曲线2结果与讨论63材料工程!2003年6期2.l加张对SiC纤维单丝强度的影响根据PCS纤维热分解过程的研究[6]600C以前纤维还是有机的强度极低而600C到1000C是剧烈的热分解阶段强度变化较大可承载负荷也在大辐度提升;1000C时纤维已基本无机化纤维强度也达到较高值可承载较大负荷O所以本研究选择两段加张体系一段在1000C前一段在1000~1250C O 加张制度与加张对SiC纤维单丝强度的影响见表1O表l加张对SiC纤维抗拉强度的影响Table1Effect of firing tension on thetensile strength of SiC fibersTension/(c -yarn-1D200~1000C1000~1250CTensile strength/GPa55 1.70105 1.77155 1.822051.61(Wholly broken at200C D1510 1.80 1520 1.78 1530 1.85 1540 1.84 1550 1.8815601.84(Partially broken at1100C D由表1可见加张可以将纤维从无张力的1.70GPa提升到1.88GPa增加约10%O但前期加张和后期加张的效果大不一样强度的提高基本上是前期加张所贡献的O实际上PCS有机纤维在热效应的作用下有热膨胀行为塑性也增强在一定的张力作用下有所伸长(1%~2%D[2]O这些伸长虽不能显著地降低纤维的直径但对于去除小弯拉直纤维使纤维之间平行程度增加还是有较大贡献的O而纤维强度的增加也就是由于小弯去除以后局部应力集中现象得到了较好控制O但是有机纤维的强度太低不宜采用过高的张力( 20c /束D O1000C烧成后纤维强度可达到1.50GPa纤维承载能力明显加强但纤维强度是呈统计分布的张力大到一定程度纤维束内部较差的纤维开始断裂O为避免产生过高的断头率第二段的张力不应超过60c /束O第二段的加张对强度的提高仍有一定的贡献这是因为1000C的纤维还含有少量的在1250C烧成之前缓慢释放伴有少量失重与收缩[6]O如没有张力局部应力集中仍难以完全避免O研究表明高温下SiC纤维可以依靠粘流过程促使表面开口气孔封闭[7]加张显然可以更有效地促进这一过程封闭开口气孔减少表面缺陷提高强度O2.2加张对SiC纤维宏观形貌的影响加张烧成的SiC纤维束的宏观形貌示于图1 并与无张力烧成的纤维束进行了对比O图1无张力(a D与有张力(b D烧成的SiC纤维束宏观形貌Fig.1Macroscopic morphology of SiC fiber bundles preparedWithout tension(a D With tension(b D and a scale ruler(c D无张力条件下烧成的SiC纤维束较蓬松局部有小弯纤维与纤维之间相互交错毛丝现象比较严重O 反之加张后烧成的纤维束结合紧密纤维平直纤维与纤维之间平行程度明显加强纤维宏观规整性与光泽度也明显改善O如上所述这种宏观形貌的改善主要得益于第一段低温加张时纤维伸长而相互趋于靠近平行O同时第二段张力作用下表面开口气孔的减少对光泽度的提高也是有利的O2.3加张对SiC纤维束丝拉伸性能的影响有张力与无张力烧成的SiC纤维束的拉伸曲线如图2所示O由图2可知无张力烧成的单根纤维之间是部分交叉的松紧程度不一致这样在拉伸时较紧的纤维首先承载较松的纤维后承载且其拉应力肯定低于较紧的纤维O所以当拉伸到一定程度后部分较紧的纤维发生断裂而使载荷出现一个小的峰值随后承载的纤维数目减少最终的断裂负荷也就明显降低O 而对于加张条件下烧成的纤维束显微镜下呈相互平行状态所以当拉伸时所有的纤维就可能同时承载O虽然由于强度统计分布的原因拉伸过程中也会有纤维不断断裂但发生这种断裂的纤维是单个进行的而不可能有多根纤维同时断裂所以其拉伸曲线近似一条直线且其最大值也与理论推导值接近[3]O 比较两种条件下的拉伸过程显然可以发现加张烧成的纤维束丝拉伸性能大大改善其断裂负荷增加(下转第40页D73加张烧成改善连续SiC纤维的束丝拉伸性能的高温场合要求硅橡胶的最高使用温度达到300C以上该胶粘剂也满足了这一高度的要求表4粘接件经高温老化后的扯离强度Table4Adhesion strength of cohesivebody after high temperature agedCohesive body 6144silicone rubber 30CrMnSiA steel PS360silicone 30CrMnSiA steel~eat-agedconditiontem-peratureCTime/h20010020000100020002 00010001 00300100200003 0~~~UTest temperature20C200C2.17 1.391.82 1.041.74 1.061.8 0.981.880.832.77 1.172.70 1.322.22 1.302.2 1.102.30 1.401.10-0.66-3结论f e23和稀土氧化物共混物作耐热添加剂使胶粘剂的耐热性能显著提高可达3 0C乙烯基三特丁基过氧化硅烷与硅橡胶混合配成胶粘剂攻克了难粘材料硅橡胶的粘接技术难点显著提高胶粘剂的粘接强度乙烯基三特丁基过氧化硅烷金属氧化物与硅橡胶混合配成胶粘剂使粘接件在室温下的粘接扯离强度达2.MPa以上在300C下的粘接扯离强度达0.83*1.4 MPa参考文献[1]林尚安.高分子化学[M] 北京:科学出版社1982.773.[2]Shied J.Adhesives~andbook3rd Ed Stoneham MassachusettsButterworth1974.[3]E L wannick et al.Rubber Chem Technol1978 2:438-63.[4]苏正涛.天津大学博士学位论文1997.31- 0.收稿日期:2003-03-16作者简介:郑诗建(1969-)男工程师在职攻读硕士从事橡胶密封材料的研究联系地址:北京81信箱7分箱(10009 ).(上接第37页)了近一倍(从7.8N升到14N)同时毛丝现象减少柔顺性增强所以可编织性也明显加强图2无张力(a)与有张力(b)烧成的SiC纤维束的拉伸曲线f ig.2Load-elongation curves of SiC fiber bundleswithout tension(a)and with tension(b)3结论(1)PCS不熔化纤维烧成过程中适当加张可以给纤维有效赋形避免小弯减少局部应力集中提高所得SiC纤维的单丝强度(2)加张烧成可以明显改善纤维之间的平行程度从而使得其断裂负荷大大增加同时加张烧成后的束丝宏观规整性加强毛丝现象减少柔顺性增强可编织性也大大加强参考文献[1]楚增勇冯春祥宋永才等.先驱体转化法连续SiC纤维国内外研究与开发现状[J].无机材料学报2002 17:193-202.[2]Z Y Chu C X f eng Y C Song et al.Influence of firing tensionon the mechanical properties of polymer-derived SiC fibers[A].proceedings of ICCM-13[C].Beijing2001.[3]Z Y Chu C X f eng Y C Song et al.Tensile strength evalua-tion of a polymer-derived multifilament continuous SiC fiber[A].proceedings of ISM2E-YS[C].Changsha2001.[4]Z Y Chu et al.Enhanced irradiation cross-linking of polycarbosi-lane[J].J Mater Sci Lett1999 18:1793-179 .[ ]Z Y Chu Y D wang C X f eng et al.Effect of spinning tech-nigues on the mechanical properties of polymer-derived SiC fiber [J].Key Eng Mater2002 224-226: 6 1-6 6.[6]Y~asegawa M Limura S Yajima.Synthesis of continuous sili-con carbide fiber with high tensile strength and high Young/s modulus[J].J Mater Sci1980 1 :720-728.[7]J LipowitZ J A Rabe L K f revel R L Miller.J Mater Sci1990 2 :2118-2124.收稿日期:2002-01-17作者简介:楚增勇(1974-)男博士研究生主要从事陶瓷先驱体与高性能陶瓷纤维的研究联系地址:湖南长沙国防科技大学一院Cf C 重点实验室(410073).04材料工程/2003年6期加张烧成改善连续SiC纤维的束丝拉伸性能作者：楚增勇， 冯春祥， 宋永才， 王应德， 王军， 肖加余作者单位：国防科技大学新型陶瓷纤维及其复合材料重点实验室,长沙,410073刊名：材料工程英文刊名：JOURNAL OF MATERIALS ENGINEERING年，卷(期)：2003(6)被引用次数：2次1.楚增勇;冯春祥;宋永才先驱体转化法连续SiC纤维国内外研究与开发现状[期刊论文]-无机材料学报 2002(02)2.Z Y Chu;C X Feng;Y C Song Influence of firing tension on the mechanical properties of polymer-derived SiC fibers 20013.Zeng-Yong Chu;Chun-Xiang Feng;Yong-Cai Song;Ying-De Wang;Jun Wang Tensile strength evaluation of a polymer-derived multifilament continuous SiC fiber[会议论文] 20014.Z Y Chu Enhanced irradiation cross-linking of polycarbosilane[外文期刊] 19995.Z Y Chu;Y D Wang;C X Feng Effect of spinning techniques on the mechanical properties of polymer-derived SiC fiber[外文期刊] 2002(224/226)6.Y HASEGAWA;M Limura;S Yajima Synthesis of continuous silicon carbide fiber with high tensile strength and high Young′s modulus[外文期刊] 19807.J Lipowitz;J A Rabe;L K Frevel;R L Miller查看详情 19901.郑春满.李效东.楚增勇.冯春祥聚碳硅烷纤维无机化过程中弯曲的形成及对SiC纤维性能的影响[期刊论文]-国防科技大学学报 2005(1)2.兰琳.夏文丽.陈剑铭.刘玲.丁绍楠.刘安华聚碳硅烷氮化热解法制备Si3 N4纤维[期刊论文]-功能材料 2013(20)引用本文格式：楚增勇.冯春祥.宋永才.王应德.王军.肖加余加张烧成改善连续SiC纤维的束丝拉伸性能[期刊论文] -材料工程 2003(6)。

Microstructured-core optical fibre forevanescent sensing applicationsCristiano M. B. Cordeiro1, Marcos A. R. Franco2, Giancarlo Chesini1,Elaine C. S. Barretto2, Richard Lwin3, C. H. Brito Cruz1, and Maryanne C. J. Large31Instituto de Fisica, UNICAMP, Campinas – SP – Brazil2Instituto de Estudos Avançados, IEAv, S. J. Campos – SP – Brazil2also with Instituto Tecnologico de Aeronáutica (ITA) – SP – Brazil3Optical Fibre Technology Centre, University of Sydney - Sydney – Australiacmbc@ifi.unicamp.brAbstract: The development of microstructured fibres offers the prospect ofimproved fibre sensing for low refractive index materials such as liquidsand gases. A number of approaches are possible. Here we present a newapproach to evanescent field sensing, in which both core and cladding aremicrostructured. The fibre was fabricated and tested, and simulations andexperimental results are shown in the visible region to demonstrate theutility of this approach for sensing.©2006 Optical Society of AmericaOCIS codes: (060.2280) Fiber design and fabrication; (060.2370) Fiber optics sensors;(999.9999) Evanescent field sensorReferences and links1.P. Russell, “Photonic crystal fibers,” Science 299, 358-362 (2003).2.J. Jensen, P. Hoiby, G. Emiliyanov, O. Bang, L. H. Pedersen, and A. Bjarklev, “Selective detection ofantibodies in microstructured polymer optical fibers,” Opt. Express 13, 5883-5889 (2005).3.P. Suresh Kumar, C. P. G. Vallabhan, V. P. N. Nampoori, V. N. Sivasankara Pillai and P. Radhakrishnan,“A fibre optic evanescent wave sensor used for the detection of trace nitrites in water,” J. Opt. A: Pure Appl. Opt. 4, 247-250 (2002).4.P. J. Wiejata, P. M. Shankar, and R. Mutharasan, “Fluorescent sensing using biconical tapers,” Sens.Actuators B 96, 315-320 (2003).5. C. M. B. Cordeiro, E. 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Opt. 42, 3509-3515 (2003).#75479 - $15.00 USD Received 27 September 2006; revised 7 November 2006; accepted 10 November 2006 (C) 2006 OSA25 December 2006 / Vol. 14, No. 26 / OPTICS EXPRESS 1305616.H. C. Nguyen, B. T. Kuhlmey, E. C. Mägi, M. J. Steel, P. Domachuk, C. L. Smith and B. J. Eggleton,“Tapered photonic crystal fibres: properties, characterization and applications,” Appl. Phys. B 81, 377-387 (2005).17.K. G. Hougaard, A. Bjarklev, E. Knudsen, S. B. Libori and J. Riishede, “Coupling Photonic CrystalFibers,” Optical Fiber Communication Conference and Exhibit, 627- 628, OFC 2002.18.M. N. Petrovich, A. van Brakel, F. Poletti, K. Mukasa, E. Austin, V. Finazzi, P. Petropoulos, E. O’Driscoll,M. Watson, T. DelMonte, T. M. Monro, J. P. Dakin and D. J. Richardson, “Microstructured fibres for sensing applications,” in Photonic Crystals and Photonic Crystal Fibers for Sensing Applications, H. H.Du, ed.,Proc. SPIE 6005, 78-92 (2005).19.Y. Huang, Y. Xu, and A. Yariv, “Fabrication of functional microstructured optical fibers through aselective-filling technique,” Appl. Phys. Lett. 85, 5182-5184 (2004).20. C. Kerbage, P. Steinvurzel, P. Reyes, P. S. Westbrook, R. S. Windeler, A. Hale, and B. J. Eggleton,“Highly tunable birefringent microstructured optical fiber,” Opt. Lett. 27, 842-844 (2002).21. C. Martelli, J. Canning, K. Lyytikainen, and N. Groothoff, “Water-core Fresnel Fibre,” Opt. Express 13,3890-3895 (2005).22.K. Patil, R. Pawar and P. Talap, “Self-aggregation of methylene blue in aqueous medium and aqueoussolutions of Bu4NBr and urea,” Phys. Chem. Chem. Phys. 2,4313-4317 (2003).23.W. J. Wadsworth, A. Ortigosa-Blanch, J. C. Knight, T. A. Birks, T. P. M. Man & P. S. Russell,“Supercontinuum generation in photonic crystal fibers and optical fiber tapers: a novel light source,” J. Opt.Soc. Am. B-Opt. Phys. 19, 2148-2155 (2002).24.P.G. Lye, M. Boerkamp, A. Ernest and D.W. Lamb, “Investigating the sensitivity of PMMA optical fibresfor use as an evanescent field absorption sensor in aqueous solutions,” J. Phys: Conference Series, 15, 262-269 (2005).25.V. Ruddy, B. D. MacCraith, and J. A. Murphy, “Evanescent wave absorption spectroscopy usingmultimode fibers,” J. Appl. Phys. 67, 6070-6074 (1990).26. B. D. Gupta, S. K Khijwania, “Experimental studies on the response of the fiber optic evanescent fieldabsorption sensor,” Fiber Integrated Opt.17, 63-73 (1998).1. IntroductionMicrostructured Optical Fibre (MOF) (also known as photonic crystal fibre (PCF) when the fibre holes are periodically arranged) is a special kind of fibre with (in general) air holes running parallel to its axis and for all its length [1]. Two types of guidance are possible in these fibres: hollow core fibres guiding by photonic band gap (PBG) or solid core fibres guiding by total internal reflection (TIR).Both approaches offer routes to improved chemical and/or biological sensing of low index materials [2] and there is an increasing body of work exploring these, both for the sensing of bulk materials and surface sensing.In conventional optical fibres, the only possible approach for sensing low refractive index materials is to use the evanescent field, which is generally very small. To increase the amount of power in the fluid of interest (the light-fluid overlap) several approaches can be applied, including plastic clad fibres (PCS) with the cladding removed [3] in the sensing region, D-shape fibres and tapers [4]. These approaches, in general, add complexity and make the structure more fragile. A simpler approach is to use the fibre merely to guide the light to a chamber that contains the gas/liquid to be measured where it is then monitored in free space. In this case the measurement is limited to short path lengths, due to practical limitations and the beam divergence.Microstructured optical fibres have vastly extended the possibilities for fluid sensing, not only because fluids can enter the microstructure directly, but also because the optical properties can be exploited to maximize the measured signal. Filled MOFs can combine the sensitivity of few microns tapered fibre with the mechanical strength of standard fibres, simultaneously offering unprecedented sensitivity and improved handling. A possible drawback could be the added complexity involved in filling and interrogating the fibre from the same point, the fibre tip. Some techniques are, however, being developed to overcome this limitation allowing the material to be inserted through a lateral hole in the fibre [5, 6].MOFs with fluids can be used in three main configurations regarding the guiding mechanism and the location of the material to be probed:#75479 - $15.00 USD Received 27 September 2006; revised 7 November 2006; accepted 10 November 2006 (C) 2006 OSA25 December 2006 / Vol. 14, No. 26 / OPTICS EXPRESS 13057a)Hollow core PBG fibres. These can be completely filled with gas or low refractiveindex liquid [7] keeping the same guiding mechanism. Potentially they can presentnear total light-fluid overlap. The fact its transmittance occurs in specific bands that are sensitive to the holes refractive index and the complex manufacturing process reducesits applications in sensing experiments;b)Liquid core TIR fibres. This approach requires a high air filling fraction cladding and a(selectively filled) liquid core [8]. Again, light-liquid overlap is very strong;c)Solid core MOFs can have their (cladding) holes filled with the material of interest.The transmittance window is broad, being limited, in practical terms, just by material loss. In the other hand, usually just a small fraction of power (the evanescent field)travels in the material to be sensed. The usual way to enhance this figure is by using fibres with a core diameter around the size of the wavelength [9].Sensing in microstructured fibres is a new area, and it is not completely clear yet all implications involved with each of the possible configurations. Due to the low spatial overlapof the light and the fluid there has been little exploration of solid core fibres for fluid sensing. There is, however, considerable room to enhance the evanescent field by tuning themicrostructure appropriately. In this work we developed a new approach where, both the core and cladding are microstructured (Fig. 1(a), white and grey are polymer, black is air). Thisdesign helps to increase the amount of energy that travels in the holes where the material can be inserted. In a different context, a MOF with hole(s) in the core was previously proposed byKoshiba [10] and Zheltikov [11] in order to control the waveguide dispersion.In this work the fibre was fabricated in polymer (PMMA-Polymethyl Methacrylate) using standard techniques [12] and has a 160 μm outside diameter and a 6.4 μm thick core. Inside the core, the seven holes are 1.75 μm wide with a 2.4 μm pitch (Λcore) [Fig. 1(a)].2. Fibre an analysisThe structure was modeled with a vectorial finite element software (COMSOL) [13]. For thenumerical analysis just a quarter of the MOF geometric model was considered to avoid extra computational time. Usually, finite element meshes with ∼ 55,000 second order triangular vectorial elements were used, corresponding to matrix systems with ∼ 380,000 degrees offreedom. Figure 1(b) shows the calculated fundamental mode at the microstructured core.The plot shows the intensity profile (power flow, time-average, z-direction) along the core cross-section while the arrows indicate the electric optical field direction. The guided optical field, shown in Fig. 1(b), resemble to the linearly polarized HE11 fundamental mode ofconventional optical fibers. Two linear orthogonal polarizations, corresponding to the degenerated fundamental modes, were found and present birefringence around 10−5. At λ= 633 nm the structure supports about eleven optical modes. The effective index of the fundamental mode was found to be 1.457828 for 633 nm, assuming air filled holes. Higherorder modes lead, in general, to an increased overlap with the low index material increasing the sensitivity [7], while potentially making the results sensitive to launch conditions andmode-mixing. Here, however, all modes have approximately the same fraction of energy traveling in the core holes, keeping the analysis simple.For some applications, including the cases when interferometric detection is used, or when the sample property to be sensed is phase encoded, a single-mode or few-mode regime is mandatory. In these cases the fibre geometry can be tailored in order to reduce the number of propagating modes by reducing the core size or by having a cladding with small air filling fraction [14]. Careful design and analysis is required to balance the competing requirements: a small number of modes (or a single mode), a high fraction of energy in the air holes and a sufficiently large core to make coupling straightforward.To quantify the fibre efficiency as a gas or liquid sensor, one important parameter is the sensitivity coefficient()fr e=, being n r the refractive index of the sensed materialnnrwithin the fibre holes and n e the modal effective index. The percentage of energy in the holes( f ) can be calculated [15]:#75479 - $15.00 USD Received 27 September 2006; revised 7 November 2006; accepted 10 November 2006 (C) 2006 OSA25 December 2006 / Vol. 14, No. 26 / OPTICS EXPRESS 13058Fig.1. Polymer (PMMA) microstructured fiber. (a) Fabricated microstructured fiber. White barindicates 20 μm. (b) Near core power flow, time-average, profile and electric optical fielddirections (arrows).()()100Re Re ****×−−=∫∫total x y y x Samplex y y x dy dx H E H E dy dx H E H E f . (1)where E x/y is the electric field in the x or y direction and H x/y is the magnetic field in the x or y direction (beam propagating in the z direction).The sensitivity coefficient r (%) is shown in Fig. 2 for the transparency region of the material used to manufacture the fibre (PMMA) and for three different filling configurations:(A) all holes are filled with air/gas (n =1), (B) all holes are filled with water (n =1.33) and (C) the cladding holes are filled with air and core holes with water. As expected, the evanescent field overlap with the sample (gas or liquid) is enhanced at longer wavelengths and when the index contrast is reduced .The value of r observed is due the mode spreading within the core holes, while the cladding holes have little influence. At 633 nm the r coefficient assumes values of 4.22% and 4.18% for the fibre completely filled with water (B) and for the fibre with core holes filled with water and cladding holes filled with air (C), respectively. If all holes are filled with air, r = 0.883% (A)Fig. 2. Sensitivity coefficient ‘r (%)’ as a function of wavelength. The marks represent: (▲)fibre with air filled holes (A), (■) fibre with water filled holes (B), and (○) fibre with core holesfilled with water and cladding holes filled with air. On the right: white is air, rose is the fibrematerial (PMMA) and blue is the fluidS e n s i t i v i t y C o e f f i c i e n t , r (%)Wavelength (μm)#75479 - $15.00 USD Received 27 September 2006; revised 7 November 2006; accepted 10 November 2006(C) 2006 OSA 25 December 2006 / Vol. 14, No. 26 / OPTICS EXPRESS 13059To highlight the impact of the core holes we also analyzed a fibre with exactly the same geometry but with a solid core (fibre presented in Fig. 1(a) with missing core holes). In this case, and again for 633 nm, the r coefficient is 0.006 % (air filled fibre) and 0.041% (water filled fibre). This means that the microstructured core increases the fraction of energy in the holes by ∼145 times when the fibre is used with gases and ∼100 times when used with liquids (n =1.33).To put these values in perspective, we compared the results of the microstructured-core MOF [Fig. 3(a)] with those of an equivalent fibre with a solid (non-microstructured core)[Fig. 3(b)] with d/Λ=0.9. The fraction of the energy was simulated as a function of the fibre core diameter (D ) and the results are presented in Fig. 4 for the cases A and B presented in Fig. 2.Fig. 3. Core diameter D of (a) microstructured core MOF and (b) regular MOFClearly, the microstructured core is very significant in increasing the sensitivity of the fibre as a sensor. As expected, the sensitivity can also be increased by reducing the size of the structure or by increasing the (d/Λ)core ratio. Scaling down the manufactured fibre by a factor of, e. g., two – D from 6.4 to 3.2 μm – enhances the ‘r’ coefficient from 4.22 % to > 17%. Increasing the (d/Λ)core from 0.72 (fabricated fibre) to 0.80 increases the ‘r’ coefficient to1.6% and to 7.3% for the air and water filled fibres, respectively.An important point, however, is that, although a solid core MOF could allow a sensitivity coefficient ‘r ’ as high as a microstructured core MOF one, the core diameter would be much smaller (Fig. 4). Having such tiny core can increase alignment precision requirements apart decreasing the field overlap between the mode of the MOF and the mode of a standard fibre.S e n s i t i v i t y C o e f f i c i e n t , r (%)Core Diameter (μm)Fig. 4. Sensitivity coefficient ‘r (%)’ @633nm for a microstructured core MOF [Fig. 3(a)](●, ■) and for a regular solid core MOF [Fig. 3(b)] (●, ■) versus fibre core diameter.D (b) D (a) #75479 - $15.00 USD Received 27 September 2006; revised 7 November 2006; accepted 10 November 2006(C) 2006 OSA 25 December 2006 / Vol. 14, No. 26 / OPTICS EXPRESS 13060To evaluate this question we modeled the coupling efficiency from a Gaussian optical beam coupling to the fundamental mode of the fibre. The maximum coupling efficiency was studied as a function of the Gaussian modal radius (a ) using the overlap factor ψ [16]. This radius (a ) represents the half-width at 1/e of the maximum intensity, being the electric field profile defined as: ())2(exp 22a r E E x −≈ . The results are shown in Fig. 5. For λ=633nm, the overlap factor of the manufactured fibre and a Gaussian optical beam occurs for a =1.5μm, and is 52% and 63% when holes are filled with air or water, respectively. For a regular MOF structure [Fig. 3(b)], as the guided mode resembles a Gaussian profile, the overlap can be > 90% [17]. It is important to recognize, however, that designing a structure such that the guided mode has a more Gaussian shape can minimize this difference.However, more important than the absolute value of the coupling efficiency is the Gaussian radius where it occurs. For a water filled fibre, and for 633nm, to reach r ~5% the core should be around 1 μm thick when using a solid core MOF or ~ 6μm when dealing with microstructured core MOFs (Fig. 4). In these cases, to obtain the maximum coupling, ‘a ’ should be 0.5 μm and 1.5 μm respectively (some results at Fig. 5). For the solid core fibre (Λ=1 μm), by using a Gaussian with 1.5 μm the coupling efficiency drops to less than 20%. This means that the microstructured core design offers an alternative means of obtaining a high light-fluid overlap while keeping a large core area.20406080100O v e r l a p (%)Gaussian Radius (μm)Fig. 5. Coupling Efficiency @ 633nm between a polarized Gaussian optical mode and a fundamental HE 11x mode propagating in the microstructured fibers. The regular MOF lattice parameters are: (d /Λ)cladding = 0.9 and Λcladding = 1 or 6 μm. The microstructured core MOF dimensions are: D =6.4 μm, core hole’s diameter d core =1.75 μm and core pitch Λcore =2.4 μm.The fibre structure was based in the triangular-lattice design where the core presents a circular-like shape. Optimization of the structure may further increase the size of the evanescent field, including the possibility of using suspended core fibres [18]. These fibres offer high sensitivity while using large holes which allows for both faster filling and the incorporation of particles (such as cells). The trade-off however is that the cores required are very small.3. Experimental resultsThe fibres were firstly tested using a He-Ne laser, which was launched into the fibre using a 20x objective lens (NA=0.40). Figure 6(a) shows an image of the fibre end-face made using a #75479 - $15.00 USD Received 27 September 2006; revised 7 November 2006; accepted 10 November 2006(C) 2006 OSA 25 December 2006 / Vol. 14, No. 26 / OPTICS EXPRESS 1306140x objective in a CCD camera. This image passed then through a polarizing beam splitter and the decomposed imaged for both vertical and horizontal polarizations are shown in Figs. 6(b) and 6(c). By comparing all three images at Fig. 6 it can be seen that it is possible to launch the light around the central hole of the core. The fibre is in the multimode regime but it is possible to couple the light mainly in a linearly polarized mode [Fig. 6(b)].Fig. 6. (a). CCD image of the guided mode. (b). and (c). pictures for both polarizations.For inserting liquids in the microstructured fibre we use a selective-filling [19-21] technique that allows filling all holes or just the external (big) ones or just the tiny core ones. Here the process involves pressurizing an UV-curable polymer inside the fibre through one of its tips [19]. The distance filled by liquid polymer will be longer for larger holes than for smaller ones and, after drying it, the fiber can be cleaved in a position where the smaller holes are open but the larger ones are blocked. The process can be repeated if one wants the opposite situation, smaller holes blocked and larger ones free to be accessed. Figure 7 shows the fibre end face in the situation where all holes are blocked [Fig. 7(a)] and where the big (external) holes are blocked and the core ones are open [Fig. 7(b)]. Figure 7(c) shows a lateral picture of the fibre so that it is possible to see the polymer inside the fibre.After doing the process described above, the fibre can then be liquid filled. In this work we filled just the core holes of the fibre with Methylene Blue (MeB) dye diluted in water. The aim was to show possible applications in liquid sensing through absorbance measurement. For real applications in sensing setups (including a light source, fibre and detector) the filling of the holes is an important issue to be addressed, a common problem that arises in any microstructured optical fibre. Some of the solutions that have been proposed include: a) using a cell in one (or both) fibre tip(s) to access the holes while keeping the core free to be illuminated and b) access the longitudinal holes thought a lateral hole in the fibre cladding [5, 6].Fig. 7. Optical micrographs of fibre cross section (A – all holes blocked and B – just claddingholes blocked with polymer) and fibre side view (C).The bulk absorption coefficient ‘α’ of MeB for several concentrations (C) is shown in Fig.8. These values were obtained by measuring, with a spectrophotometer, the different solutions in a 1 mm cuvette. The spectra show two peaks, one at 664 nm corresponding to the monomer form of the molecule and one at 612 nm due to dimer (P-type) formation. The inset shows the#75479 - $15.00 USD Received 27 September 2006; revised 7 November 2006; accepted 10 November 2006 (C) 2006 OSA25 December 2006 / Vol. 14, No. 26 / OPTICS EXPRESS 13062evolution of the peaks values (664 and 612 nm) in function of the dye concentration. As expected the bulk absorption coefficients of both the monomer and dimer forms are linearly dependent to the concentration ‘C ’. The absorption of the solution is characterized by an absorbance C molar .αα=, where ‘αmolar ’, the molar absorption coefficient, can be written as[22]:D M M M molar f f ααα)1(−+=, (2)being M f the fraction of molecules in the monomer form and αM and αD the molar absorption coefficients of the monomer and dimer respectively. In a water solution αM /αD ~ 2.3 for the dimer in its most common configuration (sandwich P-type, peak seen at Fig. 8 around 612 nm) or ~ 23 for the more unusual end-to-end configuration (N-type) [22].As can be seen from Fig. 8, in such concentration range, the main contribution for the overall absorption comes from the monomer. In more concentrated solutions aggregation of the dye molecules can occur and the relative contribution of monomer and dimer will differ.A b s o r p t i o n C o e f f i c i e n t α (c m -1)Wavelength (nm)Fig. 8. Absorption coefficient (α) of MeB for several concentrations measured in a 1mmcuvette. Inset shows the linear behavior of ‘α’ versus the dye concentration for the 664 and612 nm peaks.A 18 cm long fibre like the one of Fig. 1 was filled with MeB with concentration of3.77.10−5 mol/l (~10 times more concentrated than the last point in Fig. 8). α is estimated, extrapolating the data (bulk) from Fig. 8, to be around 53 cm -1 and 35 cm -1 for the monomer and P-type dimer respectively. A supercontinuum source [23] was coupled in the fibre core by means of a 20x objective lens. The end face of the fibre was coupled to a large core standard fibre that directed the signal to an optical spectrum analyzer (OSA). An image of the output face was taken to ensure the light was traveling in the fibre core.Figure 9 shows the spectra transmitted through a water-filled fibre and through a MeB filled fibre. The inset shows the difference (in dB) between these two signals. To aid the comparison the bulk measurement shown in Fig. 8 (at the highest concentration) was also added. These results highlight several interesting features. Most striking is that the P-dimer peak is relatively far stronger in the fibre measurement. While increased dimerisation is expected at higher concentrations, in bulk material this peak becomes stronger than the monomer peak only for concentrations an order of magnitude higher than we used in the fibre case [22]. Less obviously, the monomer peak in the fibre case is slight shifted when #75479 - $15.00 USD Received 27 September 2006; revised 7 November 2006; accepted 10 November 2006(C) 2006 OSA 25 December 2006 / Vol. 14, No. 26 / OPTICS EXPRESS 13063comparing with the bulk measurement. The likely reason for these spectral differences is the role of surface interactions.There is a few dB of noise in the fibre measurement. This is due to different coupling conditions between the two fibres and can, potentially, be improved by using a source with flatter and more stable spectrum.Evanescent field sensors preferentially probe surface effects, as the intensity of the field diminishes rapidly away from the hole interface (Fig. 10). This fast decrease is a general trend of evanescent field waves. Inside a liquid-filled core-hole the optical intensity drops to 1/e of its maximum value in just ~100 nm from the surface of the hole.This is likely to be particularly significant in this case because of surface interactions between fibre and dye. It is known that the concentration around a waveguide/fibre can be very different from the bulk concentration [24, 25]. Our results are consistent with surface-induced aggregation of the dye what makes a quantitative comparison with the bulk measurements difficult. Not only are the physical systems different, but the absorption coefficients are themselves influenced by surface interactions.-80-60-40-20S i g n a l (d B )Wavelength (nm) Fig. 9. Transmittance signal thought water filled and MeB filled fibre. The inset shows thedifference between both plots and the bulk MeB measurement (concentration=3.59 . 10−6).Nonetheless, it is instructive to quantify the absorption behavior of the solution in the fibre. From the Lambert-Beer law:()d P P α−=exp 0, (3)where ‘P 0’ is the incident power and ‘d ’ is the interaction length. When the absorbing medium is probed by an evanescent field it is also necessary to take in account the effective fraction of power ‘r ’ that is located in the absorbing medium. In this case:()rd P P dB Loss α34.4log 10)(0==. (4)As the fraction of energy within the holes are around the same for all core modes we can simply use the average value (r (%) ~ 4.28 ± 0.15, Fig. 2). In the other hand α is actually unknown, as not all the terms in Eq. (2) can be determined. The experimental results can #75479 - $15.00 USD Received 27 September 2006; revised 7 November 2006; accepted 10 November 2006(C) 2006 OSA 25 December 2006 / Vol. 14, No. 26 / OPTICS EXPRESS 13064。