This is a past event.

Dolendra Karki from National Energy Technological Laboratory (NETL) will present at this week's Physics Colloquium. Dr. Karki's presentation is titled "OPTICAL FIBER SENSORS FOR MONITORING ENERGY INFRASTRUCTURES".

The seminar will be presented  at 4:00 p.m. on Thursday (Sep.11) in Fisher 139. The coffee hour will be held at 3:30 in the Fisher Hall Lobby.

Abstract  The optical silica-fibers primarily used in high-speed data transmission and telecommunication are also fundamental to the rapidly emerging fiber-optic sensor technology. The low transmission loss and intrinsic optical scattering effects (Rayleigh, Brillouin, and Raman scattering) upon external perturbation of acoustic vibration, strain, temperature, pressure etc., make these fibers inherent sensors for remote and distributed sensing over a long distance. Higher sensitivity, immunity to electromagnetic interference (EMI), thanks to dielectric silica material, flexibility, compactness, low size and weight are other clear advantages of optical fiber-sensors over their electronic counterparts. Moreover, as a single point or multi-point sensors, the optical fiber platform offers a combination of various sensing architectures (e.g. gratings, interferometers & other specialty fibers), integration with functional sensing materials sensitive to a particular physical parameter/analyte of interest, interrogation and multiplexing methods for tailoring bandwidth, sensitivity, and range. Therefore, the wide application of fiber optic sensors spans from real-time structural health monitoring of critical civil infrastructures such as buildings, bridges, oil & gas pipelines via static and dynamic strain sensing, monitoring of energy infrastructures such as electrical grids and transformers via detection of current, temperature and gas to biomedical applications in monitoring blood components, PH, and glucose levels. With hardened silica fibers through metallic coating and fluorine-doping, the application of sensors extends to harsh environments (corrosive, high temperature, high energy-radiation) of energy power plants including nuclear reactors. However, the degraded optical and mechanical properties above 1000 C set the limit for these amorphous silica fibers and comes short when intended to measure temperature beyond. The single crystalline fibers of sapphire and yttrium aluminum garnet (YAG), which are not available commercially yet in single-mode fiber form and still the subject of R&D efforts, are the alternate optical fibers sought for applications beyond silica fibers reach. In this presentation, I will discuss some of my fiber-optic sensor development work, primarily focused on the magnetic nanoparticles-functionalized fiber optic sensors for current and current-induced magnetic field monitoring of electrical power grids. I will also report on the progress made towards growth and development of single-mode single-crystal fibers of refractory oxides via the laser heated pedestal growth (LHPG) method.

Bio Dr. Dolendra Karki is a senior research scientist working at the U.S. Department of Energy’s National Energy Technological Laboratory (NETL) branch in Morgantown, West Virginia. He is a scientific member of Leidos research support team (LRST) contributing to NETL’s research efforts in developing advanced sensors and control systems for energy-related applications. Dr. Karki received his PhD degree in physics from Michigan Technological University (MTU) in 2018 and continued his research as a postdoctoral researcher, both under supervision of Prof. Miguel Levy. He joined MEMS department, University of Pittsburgh as a senior research associate in 2021 and as an assistant research professor in 2023 prior to joining NETL in 2024. His research background and interests include magneto-optics, on-chip photonics, single crystal sapphire and silica fiber-based advanced sensors and their applications. He holds three US patents, authored/co-authored several scientific publications and is a co-winner of R&D 100 award 2024, awarded to ‘UltraSonic Photonics’ sensor technology.