Nano-scale sensing transducer using entangled photon walk-off compensation

We propose a new concept of a nano-sensing transducer system using a nano-waveguide. The small change in physical quantity affects to the change in device parameters such as refractive index or length which is relatively absorbed and observed by the resonant signals. In principle, the stored light pulse at the specified wavelength is generated by using a soliton propagating within the ring resonators, whereas a resonant signals can be stored within the nano-waveguide, i.e. a sensing transducer, which is formed by the sensing ring device. The induced change in the resonant signals by the surrounded environment is occurred, and can be detected by using the optical/quantum processor. Such a proposed device is namely suitable to perform the measurements in the nano-scale regime such as force, stress and temperature.     

Self-calibration in a fiber optic sensing system using the walk-off compensation

We firstly present a concept of a self-calibration of the classical and quantum parameters’ measurement using a fiber optic system. The measurement of the change in phase of the optimum entangled states’ visibility is performed in terms of a walk-off length, i.e. birefringence. The applied physical parameters on the sensing fiber can be simultaneously measured and the self-calibration respecting the birefringence performed. The scheme of the entangled photons generation in fiber optic is reviewed and the walk-off on the polarization entangled states presented. The potential of self-calibration and simultaneous measurement using an interferometric sensing technique and fiber grating sensor are proposed and discussed. The walk-off on the entangled states in the thermal-controlled environment is presented and discussed.     

Fiber optic flow and cure sensing for liquid composite molding

The Polymer Composites group at the National Institute of Standards and Technology has efforts in both on-line flow and cure sensing for liquid composite molding. For our flow program, a novel fiber optic real-time sensor system has been developed that can sense resin at various locations on a single fiber using long-period gratings and a polychromatic source. The sensor operation and characterization will be discussed along with sensor performance during mold filling with various types of reinforcement. The cure sensing program focuses on the interface-sensitive fluorescence response of a dye molecule grafted to a high-index glass fiber. The fluorescence emission of the fluorophore undergoes a blue shift as the resin cures. The fluorescence sensor is made by grafting a silane functional fluorophore onto the surface of the glass with close attention to layer thickness. Fluorescence emission of the grafted fluorophore film is shown to be sensitive to epoxy resin cure, co-silane, and layer thickness. The response of the grafted fluorophore to cure on a high-index fiber is demonstrated.     

Optimal sensing of current based on an extrinsic Sagnac interferometer configuration

The theory and experimental verification of an optical current sensor based on an extrinsic Sagnac interferometer configuration is presented. Superior performance with regard to current sensitivity and input/output linearity, and simple installability of the sensor makes it very suitable for remote current sensing in power distribution applications.     

Fiber Optic Spectroelectrochemical Sensing for in situ Determination of Metal Ions

In situ chemical sensing techniques are increasingly used for a variety of applications, including industrial process control, on‐site environmental assessment, and detection of explosives and chemical and biological weapons. A common category of sensors for such purposes entails the use of optical fibers for making spectral measurements of target compounds or species derived from these compounds via physical, chemical, enzymatic, or immunologic reactions. A less common but potentially advantageous approach involves the electrochemical conversion of the analyte subsequent to its spectroscopic detection. These spectroelectrochemical schemes represent versatile, essentially reagent‐free analyses that could provide superior alternatives to existing methods. Reported here is a summary of progress made by the authors' group toward the development of fiber optic spectroelectrochemical sensors for in situ measurements. The aqueous copper (II)/copper (0) couple was chosen as a model system to investigate the merit of an analytical scheme involving (i) cathodic preconcentration of Cu²⁺ as Cu⁰ followed by (ii) anodic stripping of Cu⁰ to Cu²⁺, (iii) complexation of Cu²⁺ by an appropriate ligand, and finally (iv) absorbance determination of the copper–ligand complex or fluorescence determination of the unbound ligand. Results are encouraging and indicate the need for further refinement of the sensor's design and the experimental protocol in order to improve the method's sensitivity.     

Power line monitoring system using fiber optic power supply

We propose a novel power-line-monitoring system using optical fibers for transmitting power as well as signal. The principle is experimentally confirmed with a system composed of a monitoring side with a 1.5-μm laser diode, transmission line of a single mode fiber, and a sensing side having an efficient photovoltaic (PV) cell, electrical junction sensor, and low power liquid crystal optical modulator (LCOM). The PV cell generates the electrical power in the sensing side with a conversion efficiency of 20%. The LCOM is driven with low power of less than 50 μW, modulates the laser light with a signal indicating the power line condition, and transmits the optical signal. The developed sensing unit produces an optical signal having an extinction ratio of 15 dB with low optical power of 1.8 mW. Five systems were in operation for two years, faithfully monitoring the oil pressure in electrical cables every 20 min without incident.     

Fiber optic intensity sensor referenced with a virtual delay line

In this work a self-referencing fiber optic intensity sensor using virtual instrumentation is presented. To ensure higher flexibility and dynamic optimization, the use of an optical fiber delay line or an electrical delay line is avoided by implementing a delay line in the virtual domain, preserving the self-referencing and sensitivity characteristics of the proposed optical intensity sensing structure. Results are presented where displacement is measured with an 18 μm resolution demonstrating the concept feasibility.     

一种差分吸收式光纤瓦斯传感系统

基于差分吸收法,研究了一种光纤瓦斯传感系统.采用双波长参考测量法,选取输出波长为1551nm的分布式反馈半导体激光器作为参考光源,输出波长为1 653nm的激光器作为甲烷气体的吸收峰处光源,通过改变甲烷气体吸收峰处激光器的输出波长,使其扫描到甲烷气体的吸收峰,通过比较吸收峰处和没有吸收峰处的光功率,测得甲烷气体浓度的分辨率达到0.038%.实验结果表明该系统的分辨率高、稳定性好、抗干扰能力强,可用于对煤矿瓦斯气体的检测.     

基于红蓝宝石光纤传感头的多通道光纤温度传感器

为了实现从室温到1000℃范围内的多点温度实时测量,基于红蓝宝石光纤传感探头,研制了一种连续快速温度测量的多通道光纤温度传感器.该系统结合了荧光测温和辐射测温原理,可同时测量8个传感探头的温度随时间的变化信号.提出基于面积平衡计算的数字迭代算法用来计算荧光寿命.与快速傅里叶变换算法的仿真对比结果表明,该算法计算速度快、抗噪声能力强、结果稳定性好、测量精度高.对系统进行长期的温度和稳定性实验,结果表明该系统具有较高的稳定性和测量精度,测温范围从室温到1000℃,精度达±1℃.     

Thermal analysis of the effects of thermally induced nonreciprocity in fiber optic gyroscope sensing coils

The response of interferometric fiber optic gyroscope sensing coils to a time-varying, radial thermally induced nonreciprocity is investigated. Sensing coils wind with polarization-maintaining fibers in quadrupolar wind configurations developed in our study examining the effect of radial thermal gradients are used with experimental setup. Induced gyroscope bias drift, measured as a function of temperature and time, is compensated for quadrupolar winding configurations using our model. Our results show that thermally induced nonreciprocity can be calculated with the same coefficient in difference temperature changing conditions using our model.     

Lab on Fiber Technology for biological sensing applications

This review presents an overview of “Lab on Fiber” technologies and devices with special focus on the design and development of advanced fiber optic nanoprobes for biological applications. Depending on the specific location where functional materials at micro and nanoscale are integrated, “Lab on Fiber Technology” is classified into three main paradigms: Lab on Tip (where functional materials are integrated onto the optical fiber tip), Lab around Fiber (where functional materials are integrated on the outer surface of optical fibers), and Lab in Fiber (where functional materials are integrated within the holey structure of specialty optical fibers). This work reviews the strategies, the main achievements and related devices developed in the “Lab on Fiber” roadmap, discussing perspectives and challenges that lie ahead, with special focus on biological sensing applications.

     

Quantum teleportation using entangled 3-qubit states and the ‘magic bases’

We study quantum teleportation of single qubit information state using 3-qubit general entangled states. We propose a set of 8 GHZ-like states which gives (i) standard quantum teleportation (SQT) involving two parties and 3-qubit Bell state measurement (BSM) and (ii) controlled quantum teleportation (CQT) involving three parties, 2-qubit BSM and an independent measurement on one qubit. Both are obtained with perfect success and fidelity and with no restriction on destinations (receiver) of any of the three entangled qubits. For SQT, for each designated one qubit which is one of a pair going to Alice, we obtain a magic basis containing eight basis states. The eight basis states can be put in two groups of four, such that states of one group are identical with the corresponding GHZ-like states and states of the other differ from the corresponding GHZ-like states by the same phase factor. These basis states can be put in two different groups of four-states each, such that if any entangled state is a superposition of these with coefficients of each group having the same phase, perfect SQT results. Also, for perfect CQT, with each set of given destinations of entangled qubits, we find a different magic basis. If no restriction on destinations of any entangled qubit exists, three magic semi-bases, each with four basis states, are obtained, which lead to perfect SQT. For perfect CQT, with no restriction on entangled qubits, we find four magic quarter-bases, each having two basis states. This gives perfect SQT also. We also obtain expressions for co-concurrences and conditional concurrences.     

Sensitivity-variable fiber optic pressure sensors using microbend fiber gratings

We report on sensitivity control of fiber optic sensors using microbend long-period fiber gratings. By tuning the phase difference between a pair of periodically aligned rod arrays that sandwiches a single-mode fiber, we can change the coupling strength of the core mode with radiating cladding modes, resulting in variable pressure sensitivity of the transmission power through the fiber. This technique enables control of the measurable range of pressure. When the phase difference is shifted from π toward 0, the measurable range is expanded from 1.7 to 3.3 N/cm and higher using a light-emitting diode as an input light source.     

Characterization of crosstalk of a TDM FBG sensor array using a laser source

The crosstalk characteristics of a time-division multiplexing fiber Bragg grating sensor array that uses a laser source are examined. The system performance is found to be limited by the extinction ratio of the input optical pulse modulation and can be improved significantly by properly modulating the laser wavelength.     

基于波长扫描的差分吸收光纤煤矿瓦斯传感系统设计

以1 330 nm波段的超辐射发光二极管为光源,利用可调谐光纤法珀滤波器为滤光元件,设计了一套光纤煤矿瓦斯传感系统.该系统采用了参考测量方法和差分吸收技术:一路参考光被引出用以消除光源波动的影响;扫描光纤法珀滤波器获得信号光波长和参考光波长,在实现差分吸收测量的同时,避免了不同滤光元件性能差异和中心波长漂移的影响.实验结果表明,所设计的光纤煤矿瓦斯传感系统的最低可探测甲烷浓度为0.15%.     

Fiber optic probes for linear and nonlinear Raman applications – Current trends and future development

This review focuses on fiber optic probes for linear and nonlinear Raman spectroscopy, especially for medical applications. It aims at providing an overview over contemporary technology, recent first clinical trials, and helps identifying future developments necessary to bring the emerging technology to clinical end users. After a short introduction to linear and nonlinear Raman spectroscopic modalities, general design considerations will be discussed and compared to common fiber probe setups. Subsequently, examples for medical applications of fiber optic Raman probes will be given concentrating on probes for linear Raman spectroscopy as these devices are technologically more mature compared to their counterparts based on nonlinear Raman spectroscopy. The review also includes a brief summary of first multimodal fiber optic probes and highlights their benefits for clinical applications. Finally, probes are introduced which employ either nonlinear Raman spectroscopy or surface enhanced spectroscopy.     

基于扫描激光器的边孔光纤光栅温度压力传感系统

研究了一种基于波长扫描激光器的光纤温度压力测量系统.光纤传感头为边孔光纤光栅,利用其特有的双折射特性产生双反射峰,以实现对温度和压力的同时测量.系统采用嵌入式开发技术,将激光波长扫描、光谱数据采集和以牛顿最小二乘法为核心的光栅解调算法高度整合于一体,极大降低了光纤传感系统的体积与成本.实验结果表明,在温度10~50℃、压力0~1.2 MPa时,双反射峰对应温度与压力的变化均呈现良好的线性响应特性;系统的波长解调准确度可达1pm,温度及压力的分辨率分别达到0.1℃和0.1 MPa.该系统可为温度、压力的参量测量提供低成本、小型化、性能可靠的解决方案.     

On the fiber-optic chlorine sensor with enhanced sensitivity based on the study of evanescent field absorption spectroscopy

The paper deals with a fiber optic evanescent field absorption sensor that can be used for the detection of chlorine content in drinking water. The technique is based on the absorption of evanescent fields through the development of color owing to the reaction of an organic compound diethyl phenylene diamine with chlorine, which is already present in water. In the experiment, a U-shaped optical sensor probe is used because the sensitivity of the system improves due to the higher penetration depth achieved in this case. The improvement in sensitivity (in the case of U-shaped probed) is also shown experimentally.     

Fiber optic Fabry-Perot pressure sensor with low sensitivity to temperature changes for downhole application

Pressure and temperature are two important parameters in reservoir engineering. The fiber optic sensors can be used for permanent downhole monitoring. In this paper, we propose an extrinsic fiber Fabry-Perot interferometer (EFPI) sensor for pressure measurement with low sensitivity variation. The pressure sensitivity of EFPI sensor and of the fiber Bragg grating (FBG) sensors have been measured. The experimental pressure sensitivity for EFPI and FBG sensors are measured to be 2.75 × 10⁻⁸ 1/kPa and 1.52 × 10⁻⁸ 1/kPa, respectively. The temperature cross-sensitivity problem of the EFPI sensor has been solved by a new technique. The temperature sensitivity of EFPI sensor has been decreased to 1.2 × 10⁻⁶/°C, while the temperature sensitivity of non-compensated EFPI sensor has been measured to be 16.4 × 10⁻⁶/°C. The results show that the EFPI sensor has a higher pressure sensitivity and good capability to decrease temperature sensitivity in comparison to FBG sensor.