Low-Cost Interrogation System for Long-Period Fiber Gratings Applied to Remote Sensing

• Type: Article in International Scientific Journal
• Date: 2019

Authors

dos Santos, PSS (Author) Other; Jorge, PAS (Author) FCUP; de Almeida, JMMM (Author) FCUP; Coelho, L (Author) FCUP

Journal

Title: Sensors

Vol. 19

Final page: 1500

ISSN: 1424-3210

Publisher: MDPI

Indexing

ISI Web of Knowledge - 19 Citations

Scopus - 22 Citations

Other information

Authenticus ID: P-00Q-CE2

DOI: 10.3390/s19071500

Abstract (EN): We present a portable and low-cost system for interrogation of long-period fiber gratings (LPFGs) costing around a 30th of the price of a typical setup using an optical spectrum analyzer and a broadband light source. The unit is capable of performing real-time monitoring or as a stand-alone data-logger. The proposed technique uses three thermally modulated fiber-coupled laser diodes, sweeping a few nanometers around their central wavelength. The light signal is then modulated by the LPFG and its intensity is acquired by a single photo-detector. Through curve-fitting algorithms the sensor transmission spectrum is reconstructed. Testing and validation were accomplished by inducing variations in the spectral features of an LPFG through changes either in external air temperature from 22 to 425 degrees C or in refractive index (RI) of the surrounding medium from 1.3000 to 1.4240. A dynamic resolution between 3.5 and 1.9 degrees C was achieved, in temperatures from 125 to 325 degrees C. In RI measurements, maximum wavelength and optical power deviations of 2.75 nm and 2.86 dB, respectively, were obtained in the range from 1530 to 1570 nm. The worse RI resolution obtained was 3.47x10(-3). The interrogation platform was then applied in the detection of iron corrosion, expressing wavelength peak values within 1.12 nm from the real value in the region between 1530 and 1570 nm.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14