Ultra-long chaotic FBG sensing with high-order random fiber lasing amplification

Area of Science:

• Optoelectronics and Photonics
• Fiber Optic Sensing Technology
• Distributed Sensing Systems

Background:

• Traditional correlation optical time-domain reflectometry (COTDR) systems face limitations in sensing distance.
• Achieving ultra-long-distance sensing requires robust amplification techniques that preserve signal integrity.
• Fiber Bragg Gratings (FBGs) are crucial for distributed sensing but require extended reach for large-scale applications.

Purpose of the Study:

• To develop and demonstrate an ultra-long chaotic fiber Bragg grating (FBG) sensing system.
• To significantly extend the sensing distance of COTDR by overcoming signal attenuation.
• To enable simultaneous FBG sensing and precise location determination over unprecedented lengths.

Main Methods:

• Implementation of a wavelength-scanning COTDR technique.
• Integration of sixth-order random fiber lasing amplification (RFLA) for signal enhancement.
• Utilizing cascaded random Raman fiber lasing for distributed amplification of chaotic probe light and echo signals.

Main Results:

• Experimental demonstration of a 152-km-long wavelength-scanning COTDR system.
• Achieved a spatial resolution of 6 cm for FBG sensing and location.
• Demonstrated temperature sensing with a sensitivity of 0.25 dB/°C and good linearity.

Conclusions:

• The proposed chaotic FBG sensing system with high-order RFLA offers a novel platform for ultra-long, large-capacity FBG sensing.
• This technology has significant potential for applications in overhead transmission powerline monitoring and structural health monitoring.
• The system represents a breakthrough in extending the reach of distributed fiber optic sensing.