Guides: Dr. Balaji Srinivasan and Dr. Deepa Venkitesh
Year of Joining: 2017
Research Topic: Multi-point strain/temperature sensing using Stimulated Brillouin Scattering
- Pursued B.Tech in Electronics and Communication Engineering at National Institute of Technology Silchar,Assam in 2014.
- 2 years of professional working experience as Senior Executive Engineer at Vodafone India.
Structural Health Monitoring (SHM) holds prime importance for the efficient maintenance and sustenance of capital intensive structures in any modern civic society, such as bridges, dams, airplanes and even oil/gas pipelines. The practice is so important that timely vigilance can help save millions in money as well as life. Conventionally, electrical sensors have been used to achieve SHM but such sensors face numerous challenges such as Electromagnetic Interference (EMI), and being essentially point sensors, they are prone to missing critical events that occur at places where the sensor is not physically located. On the hand optical fiber sensors inherently act as distributed sensors when scattering is used as the sensing mechanism, and have numerous advantages over electrical counterparts, such as exhibiting negligible EMI and being extremely light-weight, among several others. Stimulated Brillouin Scattering (SBS) is a scattering phenomenon that has long been in use for realising optical sensors for SHM. Various techniques making use of this phenomenon have been in development over the past, like Brillouin Optical Time Domain Analysis (BOTDA), Brillouin Optical Frequency Domain Analysis(BOFDA), Coded-BOTDA (CBOTDA), and Brillouin Optical Correlation Domain Analysis (BOCDA). All these techniques find application in specific domains depending on the requirements such as sensing range and required spatial resolution. Of all these techniques, BOCDA is the most promising technique when it comes to dynamic sensing, since we can perform both point sensing as well as distributed sensing with this technique, as per the sensing requirement, at very high acquisition speeds.
In BOCDA, both the pump and the probe lightwaves are frequency modulated with the same Frequency Modulation (FM) parameters and are counter-propagated along the fiber such that the lightwaves are highly correlated at some points/regions in the fiber while others are highly uncorrelated, thus helping to localize the Brillouin interaction to extremely narrow regions in the optical fiber.
Traditionally, BOCDA has been used for generating and sensing from a single correlation peak in the entire fiber. We are working on extending the possibilities of the technique to simultaneously sensing from multiple correlation peaks in a dynamic fashion using external phase modulation and then locking in, to each of the FM frequencies individually to extract the Brillouin Gain Spectrum (BGS) information from each of the corresponding sensing locations.
- Abhinav Agarwal, T.L. Jagadeeswar, Srijith K., Mohit S., B. Srinivasan, “Acoustic Emission-Based Leakage Detection System using Coherent Optical Time Domain Reflectometry (COTDR)”, in International Conference on Optics and Electro-Optics, Dehradun, 2019