题目：Temporal Dammann grating:  Complex superstructed Fiber Bragg Grating (FBG) for  dispersion compensation in Dense Wavelength Division Multiplexing (DWDM) fiber communication network

报告人：Yunlong Sheng

主持人：周常河研究员

时间：2019年11月1日（周五）上午10:00-11:30

地点：学院楼B4栋2003会议室

Temporal Dammann grating:  

Complex superstructed Fiber Bragg Grating (FBG) for

dispersion compensation in Dense Wavelength Division Multiplexing (DWDM) fiber communication network

Abstract

Dispersion in optical fiber will deform the signal pulse shape, increasing the Bit Rate Error (BER). Chirped FBG is used to compensate the dispersion. Phase shifts in the FBG allows complex-valued coupling coefficients, resulting in more functionalities and better performance of the FBG. Periodic phase-shifts in the FBG consist of a temporal Dammann grating, which results in spectra of FBG evenly distributed in multiple channels. However, the current method to fabricate the phase-shifted FBG introduces errors, leading to asymmetry in the channel spectra of the phase-shifted FBG. Our study on the near field diffraction by the phase mask in the fabrication of the phase-sampled FBG reveals that a phase-shift on the phase mask will split into two half phase shifts with the propagation from phase mask to fiber core. Based on this fundamental understanding, new phase mask has been redesigned and the Dense Wavelength Division Multiplexing (DWDM)  FBG was fabricated for multi-channel sampled FBGs of high channel count with equal channel amplitudes, and no asymmetry. This technique could be used for other complex fiber sensors.

Resume

Prof. Yunlong Sheng received Baccalaureate degree from University of Science and Technology of China, Beijing in 1964. He received Doctorate degree in Optics in 1982, and “Docteur d’État deFrance” degree in Physics in 1986, from P. M. Duffieux Optics Laboratory, University de Franche-Comte, Besancon, France. He joints the Center for Optics, Photonics and Lasers (COPL), University Laval, Quebec Canada in 1985 and is a full professor there.

Dr. Y. Sheng’s research interest involves holography, diffractive optics and nano-optics, optical trapping; Micro-rheology and Cell mechanics; Information optics, Pattern Recognition, image processing, image fusion, artificial neural networks (as a part of Artificial Intelligence), optical wavelet transform and compressive sensing.

Prof. Sheng has published more than 250 technical papers in the peer-reviewed journals, book chapters and international conferences, including IEEE transactions, Optics Letters, Optics Express and Nano Letters. He holds 2 international patents. His publications have been cited by international research communities by more than 5500 times with the h-index of 41. (google/scholars/Yunlong sheng).