Remote temperature sensing with low-threshold-power using erbium-doped fiber laser

Remote temperature sensing is of significant interest nowadays as it can continuously monitor structures located at tens or hundreds of kilometers away from a central location. With remote sensing, any damage of structures can be detected immediately, thus appropriate action can be taken quickly. Optical fiber laser temperature sensor is one of technologies that can be used for the implementation of remote temperature sensing. Few developments have been reported regarding the use of fiber laser for remote temperature sensing. However, in general they use Raman amplifiers which have relatively high threshold power of higher than 1 W to trigger the laser and this consequently increases the total cost for the implementation. Motivated to achieve a lower threshold power, this thesis presents a remote temperature sensor that utilizes erbium-doped fiber laser (EDFL). The configuration of the laser cavity is linear, comprising a fiber mirror reflector at one end, and the other end is formed by a fiber Bragg grating (FBG) with central wavelength of 1560 nm as the sensor head. A 30 km single mode fiber is placed before the FBG to serve as a transmission channel for remote sensing and erbium-doped fiber amplifier (EDFA) as the gain medium. The EDFA is used because it can operate using low pump power owing to the high gain efficiency of the doped-fibers. Based on this proposed design, experimental results indicate that it has a low threshold pump power of only 12 mW. In comparison to the previous study, the obtained threshold power presents an improvement of 98.8%. In addition, the laser has good stability with power fluctuations of less than 1.2 dB over a 30 minute duration, OSNR of 49 dB and power efficiency, up to 0.07%. With this fiber laser, a temperature sensor with a sensitivity of 10.6 pm/°C is realized for a temperature range from 30 °C to 90 °C which has potential to be applied in the oil and gas field. This sensitivity value is comparable with those obtained with Raman-based fiber lasers, albeit with the requirement of lower threshold pump power. The 98.8% reduction of the threshold power requirement presents opportunity for more cost effective operation in the implementation of remote temperature sensing.

Name dc:type.qualificationname

mphil

Level dc:type.qualificationlevel

masters

Grantor dc:publisher.institution

Universiti Tun Hussein Onn Malaysia

Year dc:date.issued

2021

Author dc:creator

• Jaharudin, Nurul Atika Nabila

• TA401-492 Materials of engineering and construction. Mechanics of materials

Language dc:language

en