- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Reusable fiber taper sensor based on the metastability of gold nanoparticles
摘要： This work presents the design and implementation of a reusable-tapered optical fiber sensor (RFS). We used the RFS together with a white light source to analyze the metastability of gold nanoparticles. With the RFS we observed that reaction limited aggregation occurred when modifying the concentration of metastable gold nanoparticles (MAuNPs). This was detected by a red-shift and a broadening of the absorption band. The transition from a metastable to a stable state, regardless of the concentration of the MAuNPs, was achieved by the addition of glucose. The changes in the refractive index of the solution due to the presence of glucose and the stability of the MAuNPs were successfully detected by the RFS. Diffusion limited aggregation of the MAuNPs was rapidly triggered after the addition of insulin. Finally, to gain a better understanding of our results we used Raman spectroscopy together with a hollow core photonic crystal optical fiber (HC-PCF) and studied the chemical interactions between the MAuNPs and glucose and between the MAuNPs and insulin.
关键词： glucose,Raman spectroscopy,metastable gold nanoparticles,reusable-tapered optical fiber sensor,insulin
更新于2025-09-10 09:29:36
-
Performance comparison of combining algorithms for polarization-diversity receiving in phase-sensitive OTDR
摘要： We investigate three different combining algorithms for polarization-diversity receiving in phase-sensitive optical time-domain reflectometry (φ-OTDR) system. The algorithms are equal gain combining(EGC), selective combining(SC) and max-ratio combining(MRC). We compare the performance of the three combining algorithms in three aspects, which are the SNR of the locating signal, the SNR of the recovered vibration signal and the computation cost of the algorithms. The results show that the SC algorithm has a poor locating performance and is unsuitable for locating of the system. The EGC algorithm has the lowest complexity and general locating performance, which can be applied in real-time locating of external vibration. The performance of MRC algorithm is optimal, which is a promising tool in the high SNR intrusion location system. The proper combining algorithms we chosen will contribute to achieving optimal performance and optimal resource allocation of the φ-OTDR system.
关键词： Distributed optical fiber sensor,polarization-diversity combining algorithms,φ-OTDR
更新于2025-09-10 09:29:36
-
High-Sensitivity Temperature Sensor Based on Polarization Maintaining Fiber Sagnac Loop
摘要： A high-sensitivity all-fiber temperature sensor based on a Sagnac interferometer is demonstrated by splicing a section of polarization maintaining fiber (PMF) between two sections of standard single mode fibers (SMFs). In this sensor, the SMF-PMF-SMF structure in the Sagnac loop is bent into a circle to enhance the sensitivity. The length and curvature of the PMF in the loop are investigated and can be optimized to further increase the temperature sensitivity of the sensor. Results show that the radius of the circle has an important effect upon temperature sensitivity due to the bend-induced birefringence variation of the PMF. The SMF-PMF-SMF structure bent into a circle with a radius of 30 mm exhibits a high-sensitivity temperature of 1.73 nm/℃. The sensor is provided with the advantages of easy fabrication, low-insertion loss, and high sensitivity, which may find potential applications in the field of high precision temperature measurement.
关键词： polarization maintaining fiber,Sagnac loop,Optical fiber sensor,temperature sensor
更新于2025-09-09 09:28:46
-
An Empirical Study of In-Fiber Mach-Zehnder Interferometer’s Nonlinear Temperature Response
摘要： In this paper, we explore an empirical model capable to describe the nonlinear temperature response of in-fiber Mach–Zehnder interferometers (MZI). This model describes the nonlinear and linear response ranges with the same accuracy. It shows how the refractive index of the silica and the surroundings, including their thermo-optic coefficients, contribute to the temperature sensitivity (TS). It is also capable of predicting maxima and minima values for the TS, as well the conditions for the linear response to the temperature. Five different surroundings have been tested: air, water, ethanol, turpentine, and kerosene, in a temperature ranging from 20°C to 45°C. The resulting experimental TS values have ranged from 50 pm/°C to 1000 pm/°C. At 20°C, the calculated theoretical minimum and maximum TS were 45 pm/°C and 5377 pm/°C. We also show that this model can be applied to calculate temperature from wavelength measurements with arbitrary precision, as well as it can be used to identify substances through wavelength and temperature measurements.
关键词： Mach-Zehnder interferometer,cascaded long period grating,tunable temperature sensitivity,nonlinear response,Optical fiber sensor
更新于2025-09-09 09:28:46
-
Events detection and recognition by the fiber vibration system based on power spectrum estimation
摘要： One of the important successes of optical fiber sensor established for the security system is the detection and the recognition of any type of events. The performance parameters (event recognition, event detection position, and time of detection) are unavoidable and describe the validity of any perimeter detection system. An event recognition is any signal detected within the protected area, and it is related to a non-intrusion event and an intrusion event. To achieve the detection and the recognition events at the real time, an effective two-level vibration recognition method and a technique are proposed and presented in this article. The signal characteristics (short-term energy and short-time over-threshold) have been used and compared to the dynamic threshold to judge the type of event. Then the extraction of the power distribution features on the frequency domain through power spectral estimation on the suspected intrusion signal samples is carried out and finally combined with the time-domain characteristics as feature vector through Support Vector Machine to determine the efficiency and effectiveness of the proposed vibration recognition method. The experimental simulation results show that the proposed method is effective and reliable. With collected data, it can detect and recognize the type of event in real time.
关键词： Support Vector Machine,event detection and recognition,power spectral estimation,Optical fiber sensor,dynamic threshold,short-time over-threshold,short-term energy
更新于2025-09-09 09:28:46
-
Hybrid structure Mach–Zehnder interferometer based on silica and fluorinated polyimide microfibers for temperature or salinity sensing in seawater
摘要： An all-fiber hybrid structure Mach-Zehnder interferometer (MZI) based on silica fiber and fluorinated polyimide microfiber (FPMF) for temperature or salinity sensing in seawater is proposed. Theoretically, transmission characteristic and sensing sensitivity of the MZI are derived for this kind of hybrid structure, and typical interference spectrum is observed around optical communication band. Experimentally, by tracking the shift of interference peaks, temperature and salinity sensing are demonstrated with sensitivities of about 140pm/°C and 64pm/‰, respectively, which are much higher than those of existing fiber Bragg gratings and microfiber knot resonators. In addition, dependences of sensitivity on sensor parameters, such as fiber diameter and fiber lengths, are also investigated. Unlike the other microfiber based sensors that higher sensitivity usually comes from the thinner fiber, sensors demonstrated here show that sensitivities can be tuned by changing the path-length difference of the two arms, which greatly decreases the difficulty in component fabrications. Temperature or salinity sensor demonstrated here show advantages of simple fabrication, low cost, tunable sensitivity and dynamic range, relatively high sensitivity and compatible with standard fiber optics system, which may have potential applications in developing low cost and compact size optical sensors in ocean or other liquid surroundings.
关键词： salinity,temperature,hybrid structure,microfiber,Optical fiber sensor,Mach-Zehnder interferometer
更新于2025-09-09 09:28:46