Application of Dual-Frequency Self-Injection Locked DFB Laser for Brillouin Optical Time Domain Analysis

Abstract

Self-injection locking to an external fiber cavity is an efficient technique enabling drastic linewidth narrowing of semiconductor lasers. Recently, we constructed a simple dual-frequency laser source that employs self-injection locking of a DFB laser in the external ring fiber cavity and Brillouin lasing in the same cavity. The laser performance characteristics are on the level of the laser modules commonly used with BOTDA. The use of a laser source operating two frequencies strongly locked through the Brillouin resonance simplifies the BOTDA system, avoiding the use of a broadband electrooptical modulator (EOM) and high-frequency electronics. Here, in a direct comparison with the commercial BOTDA, we explore the capacity of our low-cost solution for BOTDA sensing, demonstrating distributed measurements of the Brillouin frequency shift in a 10 km sensing fiber with a 1.5 m spatial resolution.

Core versus Surface Sensors for Reinforced Concrete Structures: A Comparison of Fiber-Optic Strain Sensing to Conventional Instrumentation

“…Given that multi-channel strain sensing was used in the research program herein, coupled with the reverse-cyclic loading protocols, the method to “rekey” was deemed to be too difficult. The authors acknowledge that it is possible that other sensor systems may be more applicable in potentially measuring larger strain values, such as that based on Brillouin scattering [ 35 , 36 ], rather than the Rayleigh-based distributed sensors used here. However, to the knowledge of the authors, Brillouin sensors, which are often used in structural health monitoring [ 37 , 38 ], generally provide lower resolutions (e.g., 10–15 cm [ 36 ] or 1.5 m [ 35 ]), which would present another limiting factor in the strain measurements for the experimental tests on the scaled wall units presented herein.…”

“…The authors acknowledge that it is possible that other sensor systems may be more applicable in potentially measuring larger strain values, such as that based on Brillouin scattering [ 35 , 36 ], rather than the Rayleigh-based distributed sensors used here. However, to the knowledge of the authors, Brillouin sensors, which are often used in structural health monitoring [ 37 , 38 ], generally provide lower resolutions (e.g., 10–15 cm [ 36 ] or 1.5 m [ 35 ]), which would present another limiting factor in the strain measurements for the experimental tests on the scaled wall units presented herein. Addressing the aforementioned practical difficulties would be a welcome future development for the application of this Rayleigh-based sensing technology to RC structural experimental testing.…”

Scientific Applications of Distributed Acoustic Sensing: State-of-the-Art Review and Perspective

“…A single fiber optic cable can potentially replace thousands of them, greatly simplifying both the measurement setup itself and the interrogation process [ 4 , 5 , 6 ]. There are three main types of scattering in an optical fiber, which are utilized in distributed sensing—Rayleigh, Brillouin, and Raman [ 1 , 4 , 7 ]. The characteristics (such as amplitude, frequency, polarization) of the scattered radiation can depend on the physical action to be monitored.…”

Improving Prediction Accuracy and Extraction Precision of Frequency Shift from Low-SNR Brillouin Gain Spectra in Distributed Structural Health Monitoring

“…At the same time, to solve a scientific or industrial problem, sensors still need to give as correct values as possible. In the case of the aforementioned sensor systems based on Rayleigh scattering, these issues are not so acute since this type of scattering is relatively strong in comparison to Brillouin scattering which is widely used in DOFS [ 15 , 16 ]. Meanwhile, systems based on these principles are applied in SHM quite often [ 17 , 18 ].…”