Yaowen Li is a Senior Researcher in the Optical Networking and Sensing Department at NEC Laboratories America. He obtained both B.S. and M.S. degrees in mechanical engineering in China. After spending seven years working on mechanical structural testing and analysis and precision optical measurement techniques, he went on to obtain his Ph.D. degree in mechanical engineering from the University of Maryland, College Park.
His thesis focused on fiber optic sensors and their demodulation schemes for dynamic strain measurements. Since his graduation, his work has been mainly on fiber Bragg gratings for telecom and industrial applications, fiber optic colorless tunable dispersion compensation devices for telecom, high-power fiber lasers, and fiber optic LiDAR systems.
His work in NEC Labs has focused on developing distributed fiber optic sensing systems for real-world applications. These systems include distributed acoustic sensors (DAS), distributed vibration sensors (DVS), distributed temperature sensors (DTS), Brillouin Optical Time Domain Reflectometry (BOTDR) based sensors, and other Rayleigh scattering-based distributed strain and temperature sensors. His current research also involves developing fiber optic microphones and hydrophone sensors for outdoor and underwater applications.
We demonstrate, for the first time, that cyclic linear pulse coding can be bipolar for BOTDA sensors, breaking the unipolar limitation of linear coding techniques and elevating the coding gain for a given code length.
Distributed fiber optical systems (DFOS) allow deployed optical cables to monitor the ambient environment over wide geographic area. We review recent field trial results, and show how DFOS can be made compatible with passive optical networks (PONs).
We demonstrate fiber optic sensing systems in a distributed fiber sensor network built on existing telecom infrastructure to detect temperature, acoustic effects, vehicle traffic, etc. Measurements are also demonstrated with different network topologies and simultaneously sensing four fiber routes with one system.
We propose a novel multi-parameter sensing technique based on a Brillouin optical time domain reflectometry in the elliptical-core few-mode fiber, using higher-order optical and acoustic modes. Multiple Brillouin peaks are observed for the backscattering of both the LP01 mode and LP11 mode. We characterize the temperature and strain coefficients for various opticalacoustic mode pairs. By selecting the proper combination of modes pairs, the performance of multi-parameter sensing can be optimized. Distributed sensing of temperature and strain is demonstrated over a 0.5-km elliptical-core few-mode fiber, with the discriminative uncertainty of 0.28°C and 5.81 ?? for temperature and strain, respectively.
We propose a single-ended Brillouin-based sensor in elliptical-core few-mode optical fiber for multi-parameter measurement using spontaneous Brillouin scattering. Distributed sensing of temperature and strain is demonstrated over 0.5 km elliptical-core few-mode fiber.
