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1

An interferometric structure with a dual-resonance long period grating for strain sensing

Zawisza R., Jaroszewicz L. R., Mikulic P., Bock W. J.

Opto-Electronics Review

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2018

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Vol. 26, No. 4

325--328

EN

Spectral characteristics and amplitude tunability of a long period grating with a dual- resonance inside fiber loop mirror are studied in terms of applied stress caused by elongation. Inserting the polariza-tion controller between grating and part of polarization maintaining fiber in the loop structure enables tuning of resonance and interferometric peaks. The maximum sensitivity of demonstrated sensor is of 1.943 dB/mε for the range of 1.1–4.4 mε. Combination of these two optical components allows to measure strain in a wider range comparing with sensors based on standard long period grating.

2

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

Mamidi V R, Kamineni S, Ravinuthala L N S P, Madhuvarasu S S, Thumu V R, Pachava V R, Putha K

Optica Applicata

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2014

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Vol. 44, nr 2

299--308

EN

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.

3

A novel method for high temperature measurements using fiber Bragg grating sensor

Reddy P. S., Sai Prasad R. L. N., Srimannarayana K., Sai Shankar M., Sen Gupta D.

Optica Applicata

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2010

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Vol. 40, nr 3

685--692

EN

This paper reports the simulation, design and experimental analysis of a fiber Bragg grating (FBG) temperature sensor, making use of chemical composition grating (CCG), which ranges from room temperature to over 900 °C. The interrogation system of the sensor proposed is simple, effective and of low cost. The sensor head comprises FBG attached to a metal plate that will be strained due to change in the length of the plate with increase in temperature. The temperature is measured on the basis of the reflected Bragg wavelength shifts from the FBG. The dynamic range of the sensor is about 30 °C to 900 °C. The proposed sensor can be employed for monitoring the health of structural members at elevated temperatures. The dynamic range of the sensor can be increased to beyond 1500 °C by making use of FBG made up of sapphire instead of silicon fiber.

4

Fiber Bragg grating and long period grating sensor for simultaneous measurement and discrimination of strain and temperature effects

Srimannarayana K., Sai Shankar M., Sai Prasad R. L. N., Krishna Mohan T. K., Ramakrishna S., Srikanth G., Ravi Prasad Rao S.

Optica Applicata

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2008

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Vol. 38, nr 3

601-608

EN

Fiber Bragg grating sensors are novel in the determination of various physical parameters. In the case of fiber Bragg grating, on a single measurement of wavelength shift, it is impossible to differentiate between the effects of changes in strain and temperature. The simulation of fiber Bragg grating, long period grating characteristics and use of the different strain-temperature response of combined sensor for the simultaneous measurement and discrimination of strain and temperature in C band are demonstrated.