Study of the integrated-optical concentration sensor for gaseous substances

The possibility of creating an integrated-optical chemical sensor that makes it possible to control the content of ammonia and other pollutants in air is demonstrated. A sensor of this type is experimentally studied. The limiting sensitivity of the integrated-optical ammonium sensor is estimated. The possibility of applying integrated-optical sensors in ecological monitoring is discussed.     

A fast integrated optical sensor of gaseous substances

We consider the design and operation of an absorption integrated optical chemical sensor, which provides control of the content of ammonia and other hazardous gaseous and liquid substances in the air. An integrated optical sensor based on a diffusion waveguide is studied. The advantage of measurement schemes in which an analog signal from the integrated-optical sensor is converted into a digital form to be processed is shown. The limiting sensitivity of such a waveguide-sensor cell istheoretically evaluated. Prospects of using such a type of integrated-optical sensors are discussed.     

一种新的白光光纤传感系统波长解调方法

提出了一种新的白光非本征法布里-珀罗干涉（EFPI）光纤传感系统的干涉谱处理方法,在白光法布里-珀罗干涉光纤传感系统中,一个中心波长为850nm的发光二极管（LED）作为宽谱光源,HR2000高分辨力微型光谱仪用来测量返回的干涉光谱。通过跟踪干涉光谱中的特定谱峰点,法布里-珀罗干涉传感器的腔长值可以被解调出来。应用反向传播神经网络,解决了单峰测量方式的级次模糊问题。反向传播神经网络能够分辨出干涉谱中不同谱峰的干涉级次,因而可以进行多个谱峰的连续跟踪。从而实现了高精密度、大动态范围的测量。进行了基于这种干涉谱处理方法的白光法布里-珀罗干涉传感系统的应变测量实验。利用该传感系统实现了精密度达0．1με,500με范围的应变测量。     

Effect of Brillouin slow light on distributed Brillouin fiber sensors

The effect of Brillouin slow light on distributed Brillouin fiber sensors (DBFSs) is studied. We demonstrate Brillouin slow light for a 1.2 ns pulse with peak powers (PS) from 3.3 to 56.2 mW on depletion of the pump power (PP) ranging from 1.3 to 83.2 mW in conventional optical fibers (SMF-28). Experiments show that, when pump power depletion is not negligible, for a given PP the Brillouin gain and delay time of a pulse decrease when PS increases in a long (> or =10 km) sensing fiber. The optimum pump beam depletion resulting from strong interaction of the pump and the probe in the fiber provides accurate temperature and strain information at a high spatial resolution. Our study reveals that at low PP the spatial resolution error caused by the pulse delay for a DBFS with centimeter spatial resolution is less than 5% of the pulse length.     

All-fused-silica miniature optical fiber tip pressure sensor

An all-fused-silica pressure sensor fabricated directly onto a fiber tip of 125 microm diameter is described. Simple fabrication steps include only cleaving and fusion splicing. Because no chemical processes are involved, the fabrication is easy, safe, and cost effective. Issues in sensor design and loss analysis are discussed. The sensor has been tested for static pressure response, showing a sensitivity of 2.2 nm/psi, a resolution of 0.01 psi (68.9 Pa), a hysteresis of 0.025%, and capability of operation at temperatures up to 600 deegrees C. This miniature sensor may be suitable for medical diagnostics, environmental monitoring, and other industrial applications.     

Miniature all-silica fiber optic pressure and acoustic sensors

We present a miniature diaphragm-based Fabry-Perot (F-P) interferometric fiber optic sensor fabricated by novel techniques for pressure or acoustic wave measurement that is only approximately 0.32 mm in diameter. By choosing different diaphragm thicknesses and effective diameters, we obtain a sensor measurement range from 5 to 10,000 psi (1 psi = 51.72 Torr) and a frequency response up to 2 MHz. In addition, the sensor's F-P cavity can be set from micrometers to millimeters with a precision of several nanometers. With the all-silica structure, the sensor is reliable, biocompatible, and immune to electromagnetic interference and has high-temperature sensing capability.     

飞秒激光制作微型光纤干涉传感器的研究进展

飞秒激光脉冲持续时间短、峰值功率高,在对物质进行处理过程中热作用区域小、加工精度高,已成为一种制作高性能、新结构光子器件的重要方法。简单介绍了飞秒脉冲激光微加工的方法和特性,归纳了飞秒激光直写技术在光纤干涉型传感器制作方面的研究进展,包括微型光纤Fabry-Perot干涉传感器和微型光纤Mach-Zehnder干涉传感器,重点介绍了这些光纤传感器的结构、特性和潜在应用。对用该技术制作的微型光纤干涉传感器进行了总结和展望。     

布里渊散射光纤传感器的交叉敏感问题

基于布里渊散射的全分布式光纤传感器的布里渊频移同时受应变和温度的影响,无法由单一的布里渊频移解析应变或温度的信息,这种交叉敏感问题制约了传感器的实用化。介绍了目前解决交叉敏感问题的主要方法及工作原理。研究了大有效面积非零色散位移光纤(LEAF)的布里渊散射谱与应变和温度的关系,实验发现布里渊谱具有三个布里渊峰,三个峰的布里渊频移与应变和温度成线性关系,第一个峰和第三个峰的布里渊峰峰值功率的差值与温度无关,但与应变成线性关系。最后基于实验结果提出了一种解决交叉敏感问题的方案,获得了大约130με的应变测量精度和8℃的温度测量精度。     

Pulse advancement and delay in an integrated-optical two-port ring-resonator circuit: direct experimental observations

We report experimental observations of the negative-group-velocity (v(g)) phenomenon in an integrated-optical two-port ring-resonator circuit. We demonstrate that when the v(g) is negative, the (main) peak of output pulse appears earlier than the peak of a reference pulse, while for a positive v(g), the situation is the other way around. We observed that a pulse splitting phenomenon occurs in the neighborhood of the critical-coupling point. This pulse splitting limits the maximum achievable delay and advancement of a single device as well as facilitating a smooth transition from highly advanced to highly delayed pulse, and vice versa, across the critical-coupling point.     

激光加工微型光纤折射率传感器的工艺与特性

提出一种由157 nm激光制造的新型微型光纤法布里-珀罗折射率传感器的制作方法,传感头由靠近单模光纤端的具有光纤顶端微通道的法布里-珀罗空气腔组成,将单模光纤顶端的微通道作为检测介质的入口.分别在珐珀腔的反射界面镀以薄膜作为反射镜面来确保高的光对比度.试验中获得了1 130.887 nm/refractive-index的分辨率.和其他的光纤传感器相比,这种传感器具有体积小,结构坚固,高分辨率,线性良好,测量范围宽等优点,能够满足实际应用的要求,特别是对需要小型传感器的场合.     

CPT Magnetometer with Atomic Energy Level Modulation

We propose and experimentally investigate a coherent population trapping state based magnetometer prototype with ^87Rb atoms. Through modulating Zeeman sublevels with an ac magnetic field, not only a phase sensitive detection scheme suitable for miniature magnetometer is realized, but also the detection resolution of magnetic field intensity could be improved by a factor of two. Our study result indicates that it is a promising low power consumption miniature sensitive low magnetic field sensor offering spatially resolved measurement at the sub-millimetre level.     

激光尘埃粒子计数器微型光学传感器的研究

研制成功便携式激光尘埃粒子计数器的核心部件———微型光学传感器。该传感器采用直角散射光收集形式,以高功率半导体激光器作为光源,同时采用高性能的PIN型光电二极管作为光电探测器。散射光收集系统为单一大数值孔径的球面反射镜,其对粒子散射光的收集角范围从20°到160°。粒子散射光信号是脉冲信号,其频谱成份主要在高频段,所以在PIN型光电二极管后用一个带通式前置放大器来消除外界的低频噪声,根据米氏散射理论计算了该光学传感器的光散射响应特性,并用聚苯乙烯标准粒子实测了该光学传感器的性能。结果表明,该系统具有高的信噪比、计数效率和尺寸分辨本领。     

基于2S2G棱镜的新型反向表面等离子共振生物传感器

提出了一种基于反向表面等离子体共振原理,由Ge_(20)Ga_5Sb_(10)S_(65)-钯-石墨烯分子-生物分子四层结构构成的新型生物传感器。当生物分子之间发生相互作用时,引起生物分子层折射率的变化,从而导致反向表面等离子体共振角的偏移。在此基础上,根据传输矩阵法推导了传感器的输出光谱,重点讨论了本文提出的传感器与传统传感器相比,在灵敏度、分辨率、动态检测范围以及检测信号信噪比方面取得的进展。另外,通过对比研究,深入分析了辅助介质层石墨烯厚度对传感器性能的影响。最后,利用近红外光作为提出的传感器的入射光,分析了在近红外区域传感器性能的改善。研究结果表明:单层石墨烯分子使传感器性能达到最佳;反向表面等离子共振峰强度约为入射光强的80%~90%,使传感器的输出信号具有较大的信噪比;在可见光区域,当入射光波长为632.8nm时,提出的反向表面等离子共振生物传感器的分辨率是基于SiO_2棱镜耦合反向表面等离子共振生物传感器的1.9倍,是传统表面等离子共振生物传感器的3.5倍,提出的传感器的动态检测范围约是现有传感器的2倍;利用Ge_(20)Ga_5Sb_(10)S_(65)棱镜可使反向表面等离子共振生物传感器检测光波长由可见光区域扩展到近红外区域,当入射光为1 000nm时,传感器的分辨率是可见光区域的3~4倍。该研究对基于反向表面等离子体共振原理生物传感器的实现与发展具有重要意义。     

Mechano-optical waveguide on-off intensity modulator

High-extinction on-off modulators are essential for channel selection in integrated-optical sensor arrays. We report a standard SiON-technology-based electrostatically driven integrated mechano-optical waveguide on-off intensity modulator. On-off modulation is achieved by movement of an absorbing element into and out of the evanescent field of the guided mode. An extinction ratio of >37 dB at an actuation voltage of <30 V was achieved in a 6 mmx4 mm device for a wavelength of 632.8 nm. Full wafer-scale fabrication is made possible by use of chemical mechanical polishing and aligned wafer bonding.     

激光微加工制作的微光纤珐-珀加速度传感器

将157nm激光微加工制作的微光纤珐-珀腔贴于悬臂梁结构构成加速度传感器。通过设计特定的悬臂梁结构和FFT方法,该加速度传感器的分辨率约为1．13mg／HZ1/2。通过采用MUSIC算法处理信号,信噪比可提高45dB,系统分辨率约为3．56×10^-2μg／Hz1/2。该微光纤珐一珀传感器具有可批量制作、成本低、抗高温、量程灵活等优点,有望应用于石油勘探、地震测量等领域中。     

All-fiber high-sensitivity pressure sensor with SiO2 diaphragm

The design and fabrication of a miniature fiber Fabry-Perot pressure sensor with a diameter of 125 microm are presented. The essential element in the process is a thin SiO2 diaphragm that is fusion spliced at the hollow end of an optical fiber. Good repeatability and high sensitivity of the sensor are achieved by on-line tuning of the diaphragm thickness during the sensor fabrication process. Various sensor prototypes were fabricated, demonstrating pressure ranges of from 0 to 40 kPa to 0 to 1 MPa. The maximum achieved sensitivity was 1.1 rad/40 kPa at 1550 nm, and a pressure resolution of 300 Pa was demonstrated in practice. The presented design and fabrication technique offers a means of simple and low-cost disposable pressure sensor production.     

Reflective photoluminescence fiber temperature probe based on the CdSe/ZnS quantum dot thin film

A reflective fiber temperature sensor based on the optical temperature dependent characteristics of a quantum dots (QDs) thin film is developed by depositing the CdSe/ZnS core/shell quantum dots on the SiO₂ glass substrates. As the temperature is changed from 30 to 200°C, the peak wavelengths of PL spectra from the sensing head increase linearly with the temperature, while the peak intensity and the full width at half maximum (FWHM) of PL spectra vary exponentially according to the specific physical law. Using the obtained temperature-dependent peak-wavelength shift, the average resolution of the designed fiber temperature sensor can reach 0.12 nm/°C, while it reaches 0.056 nm/°C according to the FWHM of PL spectrum.     

Theory of absorption integrated optical sensor of gaseous materials

The eigen and noneigen (leaky) modes of a three-layer planar integrated optical waveguide are described. The dispersion relation of a three-layer planar waveguide and other dependences are derived, and the cutoff conditions are analyzed. The diagram of propagation constants of the guided and radiation modes of an irregular asymmetric three-layer waveguide and the dependence of the electric field amplitudes of radiation modes of substrate on vertical coordinate in a tantalum integrated optical waveguide are presented. The operating principles of an absorption integrated optical waveguide sensor are investigated. The dependences of sensitivity of an integrated optical waveguide sensor on the sensory cell length, the coupling efficiency of the laser radiation into the waveguide, the absorption cross-section of the studied material, and the level of additive statistical noise are investigated. Some of the prospective areas of application of integrated-optical waveguide sensors are outlined.     

利用红外光谱成像技术研究PP/PE共混物

利用红外光谱对不同比例条件下制备的PP PE共混物进行了研究 ,通过对PP ,PE的特征吸收峰的分析 ,发现聚丙烯 (PP)特征峰峰面积与聚乙烯 (PE)特征峰峰面积的比值与PP/PE共混物的质量比之间存在较好的对应关系。利用特征吸收峰面积之比 ,借助红外成像技术对PP纤维热压在PE薄膜上制备的样品的研究得到了复合共混物的分布信息 ,发现其成像结果与偏光显微镜的结果有很好的吻合。实验研究结果表明采用红外成像技术 ,利用特征吸收峰面积之比可以进行对聚合物共混物的分相行为的研究。     

Planar metamaterial analogue of electromagnetically induced transparency for a miniature refractive index sensor

A planar metamaterial of analogue of Electromagnetically Induced Transparency (EIT-like) is theoretically and experimentally investigated. The EIT-like metamaterial unit cell, whose electrical size is only $0.2{\lambda }_0$, consists of a split ring resonator (SRR) and a folded-line pair resonator (FLPR). For the TM wave incidence, a sharp transmitted peak with high quality factor can be observed. The EIT-like metamaterial is fabricated and measured. Good agreement is obtained between the simulation and measurement results. A miniature refractive index sensor based on the proposed metamaterial is simulated and exhibits high sensitivity and Figure of Merit (FOM).