A cost-effective edge-filter based FBG interrogator using catastrophic fuse effect micro-cavity interferometers

A graphene diaphragm integrated silica fiber Bragg grating (FBG) based sensor head was developed for simultaneous determination of water level and temperature. This new design used two FBG sensors with uniform grating made of SMF-28 fiber with 1550 nm of central wavelength, bandwidth of 0.5 nm, 4 mm length and 90% reflectivity. The response of the sensor to water level was monitored in terms of Bragg wavelength shift, which is proportional to the strain. Upon immersing inside the water column, the diaphragm gets deformed due to a strain originated from the water level imposed hydrostatic pressure. A linear response of the sensor head was achieved for water level in the range of 0–100 cm. The FBG based sensor head revealed high detection sensitivity ∼24.84 pm/cm. The temperature measurement sensitivity of the sensor was 13.31 pm/°C in the range of 27–77 °C. The water level detection sensitivity was found to reduce with increasing thickness of the graphene diaphragm.

Graphene diaphragm integrated FBG sensors for simultaneous measurement of water level and temperature

This paper reviews fiber Bragg grating sensing technology with respect to its use in mainstream industrial process applications. A review of the various types of sensors that have been developed for industries such as power generation, water treatment and services, mining, and the oil and gas sector has been performed. A market overview is reported as well as a discussion of some of the factors limiting their penetration into these markets. Furthermore, the author’s make recommendations for future work that would potentially provide significant opportunity for the advancement of fiber Bragg grating sensor networks in these mainstream industries.

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Fiber Bragg Grating Sensors for Mainstream Industrial Processes

A fiber Bragg grating (FBG) pressure sensor with high sensitivity and resolution has been designed and demonstrated The sensor is configured by firmly fixing the FBG with a metal bellows structure The sensor works by means of measuring the Bragg wavelength shift of the FBG with respect to pressure change From the experimental results, the pressure sensitivity of the sensor is found to be 906 pm/psi, which is approximately 4000 times as that of a bare fiber Bragg grating A very good linearity of 9986% is observed between the Bragg wavelength of the FBG and applied pressure The designed sensor shows good repeatability with a negligible hysteresis error of ± 029 psi A low-cost interrogation system that includes a long period grating (LPG) and a photodiode (PD) accompanied with simple electronic circuitry is demonstrated for the FBG sensor, which enables the sensor to attain high resolution of up to 0025 psi Thermal-strain cross sensitivity of the FBG pressure sensor is compensated using a reference FBG temperature sensor The designed sensor can be used for liquid level, specific gravity, and static/dynamic low pressure measurement applications

/pdf/fbg-based-high-sensitive-pressure-sensor-and-its-low-cost-19t614qhse.pdf

FBG based high sensitive pressure sensor and its low-cost interrogation system with enhanced resolution

A novel fiber optic temperature sensor based on a liquid-core multimode interference device is demonstrated. The advantage of such structure is that the thermo-optic coefficient (TOC) of the liquid is at least one order of magnitude larger than that of silica and this, combined with the fact that the TOC of silica and the liquid have opposite signs, provides a liquid-core multimode fiber (MMF) highly sensitive to temperature. Since the refractive index of the liquid can be easily modified, this allows us to control the modal properties of the liquid-core MMF at will and the sensor sensitivity can be easily tuned by selecting the refractive index of the liquid in the core of the device. The maximum sensitivity measured in our experiments is 20 nm/°C in the low-temperature regime up to 60 °C. To the best of our knowledge, to date, this is the largest sensitivity reported for fiber-based MMI temperature sensors.

https://www.mdpi.com/1424-8220/15/10/26929/pdf

Highly Sensitive Liquid Core Temperature Sensor Based on Multimode Interference Effects.

A fiber Brag grating-based high temperature sensor together with a low cost, high speed and compact size interrogation system using a long period grating was designed, developed and tested. The designed sensor measures the temperature from room temperature to 550 °C. The sensor head was configured by encapsulating an fiber Brag grating (type-I) of Bragg resonance wavelength at 1552.88 nm in a capillary tube made of copper. Long period grating with peak transmission loss at 1550 nm was employed to convert the wavelength information from fiber Brag grating into an intensity modulated signal. Temperature related optical intensity information was again converted into its equivalent electrical signal by using a photodiode. The achieved resolution of the sensor was found to be 0.5 °C.

/pdf/fiber-bragg-grating-based-high-temperature-sensor-and-its-53sv83cfo6.pdf

L. N. S. P. Ravinuthala

Papers

Fiber Bragg grating-based high temperature sensor and its low cost interrogation system with enhanced resolution