Hybrid Raman/fiber Bragg grating sensor for distributed temperature and discrete dynamic strain measurements

Area of Science:

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

Background:

• Traditional fiber optic sensing often requires separate systems for static and dynamic measurements.
• Fiber Bragg gratings (FBGs) are widely used for strain and temperature sensing but dynamic interrogation can be complex.
• Integrating distributed and discrete sensing modalities presents a significant challenge in optical fiber systems.

Purpose of the Study:

• To propose and demonstrate a novel hybrid fiber optic sensing technique.
• To achieve simultaneous distributed static temperature and discrete dynamic strain measurements.
• To develop a highly integrated sensing scheme using fiber Bragg gratings.

Main Methods:

• Combining Raman optical time domain reflectometry (ROTDR) with in-line time-division-multiplexing (TDM).
• Utilizing broadband apodized low reflectivity FBGs.
• Employing a single narrowband optical source and a shared receiver block.

Main Results:

• Successful experimental demonstration of the proposed hybrid sensing technique.
• Simultaneous measurement of distributed static temperature and discrete dynamic strain achieved.
• High integration of sensing components realized over the same sensing fiber.

Conclusions:

• The hybrid ROTDR-TDM FBG interrogation technique offers a versatile solution for simultaneous static and dynamic strain/temperature monitoring.
• This approach simplifies sensor system design by using a single fiber and shared hardware.
• The demonstrated technique has potential applications in structural health monitoring and distributed sensing.