Fiber Temperature Sensor Research Articles

Design and data processing for high-accuracy fluorescence lifetime of optical fiber temperature sensor using extended Kalman filter algorithm

Design and data processing for high-accuracy fluorescence lifetime of optical fiber temperature sensor using extended Kalman filter algorithm

Analysis of the Heat Transfer Performance of a Buried Pipe in the Heating Season Based on Field Testing

Ground source heat pump (GSHP) systems have been widely used in the field of shallow geothermal heating and cooling because of their high thermal efficiency and environmental friendliness. A borehole heat exchanger (BHE) is the key part of a ground source heat pump system, and its performance and investment cost have a direct and significant impact on the performance and cost of the whole system. The ground temperature gradient, air temperature, seepage flow rate, and injection flow rate affect the heat exchange performance of BHEs, but most of the research on BHEs lacks field test verification. Therefore, this study relied on the results of a field thermal response test (TRT) based on a distributed optical fiber temperature sensor (DOFTS) and site hydrological, geological, and geothermal data to establish a corrected numerical model of buried pipe heat transfer and carry out the heat transfer performance analysis of a buried pipe in the heating season. The results showed that the ground temperature gradient of the test site was about 3.0 °C/100 m, and the temperature of the constant-temperature layer was about 9.17 °C. Increasing the air temperature could improve the heat transfer performance. The temperature of the surrounding rock and soil mass of the single pipe spread uniformly, and the closer it was to the buried pipe, the lower the temperature. When there is groundwater seepage, the seepage carries the cold energy generated by a buried pipe’s heat transfer through heat convection to form a plume zone, which can effectively alleviate the phenomenon of cold accumulation. With an increase in seepage velocity, the heat transfer of the buried pipe increases nonlinearly. The heat transfer performance can be improved by appropriately reducing the temperature and velocity of the injected fluid. Selecting a backfill material with higher thermal conductivity than the ground body can improve the heat transfer performance. These research results can provide support for the optimization of the heat transfer performance of a buried tube heat exchanger.

High-sensitivity fiber temperature sensor based on composite film structure and lossy mode resonance

In this work, we proposed and demonstrated a high-sensitivity optical fiber temperature sensor based on lossy mode resonance (LMR). The sensor is composed of a D-shaped fiber and a thin composite film. The composite film consists of tin dioxide (SnO2) and polydimethylsiloxane (PDMS). PDMS is inserted as an intermediate layer between D-shaped fiber and SnO2 layer, realizing the separation of TM and TE polarization to reduce polarization crosstalk, while also serving as a temperature sensitive layer. The polarization state of the excited LMR can be freely controlled by adjusting the thickness of the composite film. The proposed sensor exhibits a high temperature sensitivity of −1.1883 nm/°C with a measurement range of 10–90 °C. Meanwhile, a fast response time of ∼ 109 ms was observed due to the ultra-thin PDMS interlayer.

GSM Based of Unclad Fibre Temperature Sensor for Electrical Transmission Cable Monitoring System

This paper presents a temperature monitoring system for an electrical transmission cable utilizing a global mobile service (GSM)-based unclad fibre sensor. The developed system consists of GSM module, Arduino controller, unclad plastic optical fibre (POF) sensor, light emitting diode (LED) and photodetector. The unclad POF sensor was chosen due to its immunity towards electromagnetic interference as well as its high sensitivity performance. In this work, the transmission cable hazardous temperature is set at 70oC, which is the maximum operating temperature value provided by the National Electrical Code (NEC) NFPA 70. For system characterization, temperature of the cable was varied from 30oC to 70oC. Photodetector output voltage for this temperature variation were recorded at 660 nm and 770 nm operating wavelength. The recorded data shows that the sensor sensitivity performances at 660 nm wavelength are found superior than 770 nm wavelength, which are 0.9710mV/oC and 0.9699mV/oC respectively. As for the GSM communication system, the system was characterized based on accuracy of the information send via GSM text message and its delay. The developed system offers economical and practical monitoring system to be adopted for transmission cable temperature monitoring in remote area.

A compact, highly sensitive optical fiber temperature sensor based on a cholesteric liquid crystal polymer film

A compact, highly sensitive optical fiber temperature sensor based on a cholesteric liquid crystal polymer film

Ultracompact Transverse Load and Temperature Fiber Sensor Probe Based on Cascaded Polymer Microspheres With Vernier Effect

Ultracompact Transverse Load and Temperature Fiber Sensor Probe Based on Cascaded Polymer Microspheres With Vernier Effect

Fiber temperature sensor based on dual-wavelength emitting Mg0.388Al2.408O4: Mn2+/Mn4+ phosphors for real-time temperature monitoring

Single doped Mg0.388Al2O3.408O4 phosphor was prepared and multivalent Mn ion (Mn2+ and Mn4+) emission was achieved in a single host. The structure, morphology, and luminescence characteristics of Mn ions in Mg0.388Al2O3.408O4 were discussed in detail, especially the temperature dependent emission characteristics of Mn ions. Based on the fluorescence intensity ratio (FIR) of Mn2+versus Mn4+ and the decay lifetime of Mn4+ emission as the temperature readout, a dual-mode optical temperature-sensing mechanism was proposed and studied in the temperature range of 293–473 K. The maximum relative sensitivities (Sr) are derived as 2.83 % K−1 (at 373 K based on FIR) and 3.40 % K−1 (at 473 K based on decay lifetime), respectively. The temperature sensing characteristics of Mg0.388Al2.408O4: Mn2+/Mn4+ powders in a full fiber system were studied, which can provide thermal-sensitive emissions at dual-wavelengths for stable ratiometric temperature sensing with good precision and repeatability. The constructed all fiber temperature sensing system has been applied in the on-line monitoring of CPU temperature.

Design of a Fiber Temperature and Strain Sensor Model Using a Fiber Bragg Grating to Monitor Road Surface Conditions

In this paper, the types and principles of operation of fiber sensors based on fiber Bragg gratings (FBGs) are investigated. The influence of strain and temperature on the characteristics of FBGs is considered, and a method for the simultaneous measurement of these parameters is presented. Laboratory studies were carried out in the temperature range from +18 °C to +135 °C with an incremental step of 5 °C, with the actual temperature not deviating by more than ±0.5 °C. From the data obtained, the Bragg wavelength–temperature relationships were plotted, which showed a linear increase in wavelength with increasing temperature. This study shows that the use of two FBGs with a different sensitivity to temperature and strain allowed for the simultaneous measurement of both parameters. Numerical models created in the MATLAB R2022b environment confirmed the high accuracy and precision of the measurements. The FBG-based sensors demonstrated a robust performance in harsh environments, withstanding temperatures of up to 160 °C and high humidity, making them applicable in various industries and sciences. This work confirms that FBGs are a promising tool for accurate temperature and strain measurements, providing reliable results in harsh environments.

Development of a high-sensitivity and fast-response fiber temperature sensor utilizing Ti3C2TX MXene/PDMS composites and Vernier effect

Precisely measuring temperature holds great significance for human daily life and industrial production. A high-sensitivity and fast-response optical fiber temperature sensor based on the vernier effect is proposed. A Fabry-Perot interferometer (FPI) filled with Ti3C2TX MXene and polydimethylsiloxane (PDMS) composites is employed as a sensing probe for the first time, and a cascaded Mach-Zender interferometer (MZI) as a reference unit due to its insensitivity to temperature. The temperature sensitivity of the FPI filled with Ti3C2TX MXene/PDMS composites is 1.63 nm/°C owing to the excellent thermal expansion characteristics of PDMS, and the response time is shortened from 3.021 s to 719 ms compared to that of the FPI filled with pure PDMS attributed to the high thermal conductivity of MXene. The cascading of FPI and MZI with similar free spectral ranges generates the vernier effect. The sensitivity is magnified by 19.44 times, reaching up to 31.62 nm/°C in the range of 36.5 - 37.2 °C, and the response time is 721 ms. Furthermore, experimental results demonstrate the sensor’s good stability, implying its potential applications of the sensor in medical diagnosis, environmental monitoring and biosensing.

Improving the sensitivity of a plasmonic photonic crystal fiber temperature sensor by introducing an array of nanoscale gold rods

Improving the sensitivity of a plasmonic photonic crystal fiber temperature sensor by introducing an array of nanoscale gold rods

A miniature temperature sensor based on upconversion luminescence for real-time GPU temperature monitoring

This paper introduces a miniaturized optical fiber temperature sensor based on Fluorescence Intensity Ratio (FIR) technology for real-time monitoring of graphics processing unit (GPU) temperature. Utilizing a femtosecond micromachining system, miniature rectangular holes are etched on a standard multimode fiber. These holes are then filled with a mixture of Er3+/Yb3+ co-doped TeO2-Na2CO3-ZnO powder and polydimethylsiloxane (PDMS) through capillary action, forming a sandwich structure. When illuminated by a 980 nm light source, upconversion (UC) fluorescence is generated, and a mathematical model correlating the fluorescence intensity ratio of two adjacent energy levels with temperature is established. The fundamental temperature sensing characteristics of the sensor are tested in a temperature-controlled chamber, with a maximum error of ± 1 K. The sensor is also applied to a GPU with real-time temperature variations, demonstrating a maximum error of 0.9 K and a response time of 1.96 s. The sensor not only possesses the advantages of a simple structure, micro size, and convenient fabrication but also exhibits immunity to electromagnetic interference, rapid response, good stability, and excellent repeatability in real-time monitoring of GPU temperature, showing potential for large-scale application.

Dual-core fiber temperature sensor based on bending assist and spot pattern demodulation

A high sensitivity temperature sensor based on spot pattern demodulation of rare doped dual-core fiber (RDCF) is proposed. By utilizing the interference and scattering in RDCF, the related temperature variations can be captured by optical field. Furthermore, In order to improve the sensitivity, the RDCF is given a certain amount of bending. Due to the change of the spot mode caused by bending, the temperature changes more to the refractive index of the fiber core, so that the spot of the fiber changes more to facilitate the subsequent spot identification. In addition, considering the global and subtle nature of spot changes, a deep learning algorithm based on AlexNet transfer model is used to process image recognition at multiple temperatures. The experimental results show that the sensor can perceive different temperature in range of 30–199 °C, and the resolution is higher than 0.05 °C. These outstanding results indicate that the bending assisted temperature sensor based on spot pattern decoding of RDCF has potential applications in temperature quantitative sensing and artificial intelligence perception.

Dual-core Photonic Crystal Fiber Temperature and Humidity Sensor Based on PDMS and PVA

Dual-core Photonic Crystal Fiber Temperature and Humidity Sensor Based on PDMS and PVA

A four core fiber temperature and strain dual parameter sensor based on T-shaped taper

A four core fiber temperature and strain dual parameter sensor based on T-shaped taper is proposed and prepared. The sensor is composed of single-mode fiber (SMF), multi-mode fiber (MMF), and four core fiber (FCF). Among them, MMF plays a role in beam expansion, and FCF is tapered and fused with SMF to form a T-shaped taper structure, thereby preparing a sensor based on Mach Zehnder interference principle. When the external environmental temperature and strain change, due to thermal effect and elastic optical effect, the refractive index of the FCF cladding and fiber core changes differently, resulting in shift in the interference spectrum. Based on the temperature and strain sensitivity at different interference valleys, the temperature and strain dual parameter matrix equation of the sensor can be obtained. The experimental results indicate that when the temperature rises within the range of 30 ℃ to 90 ℃, the sensor spectrum shows a red shift phenomenon, and the maximum temperature sensitivity can reach 55 pm/ ℃. When the strain increases within the range of 0 με∼ 2000 με, the transmission spectrum of the sensor exhibits a blue shift phenomenon, and the maximum strain sensitivity can reach −2.6 pm/ με. Finally, based on the experimental results, the matrix equation for dual parameter sensing can be obtained. This sensor is easy to manufacture and has high sensitivity. It can measure sensing parameters normally in micro magnetic and micro electric field environments.

Microwave photonics demodulation based on a fiber loop and a virtual Fabry-Perot interferometer for sapphire fiber temperature sensors

Microwave photonics demodulation based on a fiber loop and a virtual Fabry-Perot interferometer for sapphire fiber temperature sensors

Fiber optic relative humidity and temperature sensor with the cascaded Vernier effect based on the C-shaped cavity structure

The water-absorbent sensing film, coated on the surface of traditional optical fiber humidity sensors, often suffers from detachment issues. In this paper, we present what we believe to be a new fiber-optic cascaded Fabry-Perot interferometer sensor for detecting relative humidity (RH) and temperature, without the need for sophisticated instrumentation. The sensing structure comprises two sections of single-mode optical fibers and a C-shaped cavity between them. The C-shaped cavity is created by grinding the side of a hollow-core fiber with fiber optic abrasive paper. The Vernier effect arises from the cascaded interaction between the C-shaped cavity filled with ultraviolet optical glue (NOA61) and the subsequent single-mode fiber pigtail. The sensor exhibits a high RH sensitivity of 0.248 nm/%RH (35-95%RH) and an RH resolution of up to 0.08%RH. It also has high-temperature sensitivities of -1.091 nm/°C (25 - 65°C). Furthermore, simultaneous measurement of RH and temperature is achieved by establishing a dual parameter matrix, and the sensor's response time and recovery time for RH and temperature are within 300s. Therefore, this work provides a simple and cost-effective manufacturing process and the proposed RH and temperature sensor features a compact size, strong environmental adaptability, and significant potential for practical applications.

Cladding modes’ interference in MM-tapered SM-MM fiber devices: Experimental demonstration of a high-sensitivity temperature sensor

Here, we report our experimental demonstration of a high-performance temperature sensor fabricated by cascading dissimilar multimode fibers and tapered single mode fiber coated with an index-matching gel of high thermo-optic coefficient. The output power is recorded under varying temperature conditions of the coated material. Besides wavelength-shifting based multimode interferometer sensor, here a unique methodology is adopted where an intensity based fiber temperature sensor is realized. Our optimized design yields a temperature measurement sensitivity of 8.1253 µW/°C, accuracy of ± 0.9 0C, response time of 392 ms and resolution of 0.1 0C within the range of 29 °C to 64 °C. Analytical mode overlap and Ansys Lumerical simulation validate experimental results, affirming the method's effectiveness.

High sensitivity optical fiber temperature sensor based upon a polydimethylsiloxane filled Fabry-Perot interferometer

A high-sensitivity temperature sensor based upon an optical fiber Fabry-Perot interferometer (FPI) filled with polydimethylsiloxane (PDMS) is reported that employed a single mode fiber (SMF) and a hollow core fiber (HCF) to enhance the sensitivity. The sensing characteristics were investigated from 20 °C to 40 °C. The experimental results demonstrate that the sensor is sensitive to temperature due to the high thermal optical coefficient (TOC) and high thermal expansion coefficient (TEC) of PDMS, achieving a high sensitivity of 2.155 nm/°C. The designed sensor shows great potential for high-precision temperature sensing applications due to its high sensitivity, compact structure, and simple preparation.

Photonic crystal fiber temperature sensor based on self-phase modulation and solitons

In this paper, we investigated the temperature sensing properties of self-phase modulation (SPM) combined with solitons in photonic crystal fibers by experimental verification. Pumped in the normal dispersion region close to the zero-dispersion point, SPM allows the resulting spectrum to extend into the normal dispersion region, generating solitons. By detecting the wavelength shift of the soliton at 900 nm, 2.366 W, the maximum sensitivity is 0.98 nm/°C. To the best of our knowledge, this is the first study of temperature sensing using SPM in combination with solitons, which broadens the boundaries of nonlinear-based sensors and holds considerable promise for high-performance temperature detection in a variety of demanding scenarios, such as railway safety and national security.

Discharge splicing-free ultra-highly sensitive fiber-optic temperature sensor based on PDMS and the Vernier effect

A novel discharge splicing-free ultra-highly sensitive fiber-optic temperature sensor, based on polydimethylsiloxane (PMDS) and the Vernier effect, is constructed and experimentally validated. The sensor comprises single mode fiber (SMF), hollow core fiber (HCF), and PDMS. The Vernier effect is produced by the PDMS cavity and the mixed PDMS-air cavity during fabrication. By virtue of the Vernier effect and the temperature-sensitive material PDMS, this sensor shows an exceptionally high temperature sensitivity of −4.08658 nm/℃ while maintaining an outstanding linearity of 0.99972. The repeatability and stability have been demonstrated by subjecting the sensor to three cycles of heating and cooling, each with a 24-hour interval. Furthermore, experimental results indicate that the sensor exhibits excellent resistance to microvibrations and the interference occurs inside the structure, enabling its reliable operation in harsh environments without additional package. The miniature fiber temperature sensor is easily fabricated, highly sensitive, and demonstrates exceptional stability and repeatability, serving an ideal alternative for measuring temperature in challenging conditions.