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视频信息

标题:Optical fibers for OAM mode transmissions
主讲人:Sophie LaRochelle Professor 主办单位: 讲座时间:2014-11-07 00:00:00
简 介:
						

In today’s information world, people and devices worldwide are constantly exchanging data through the cloud. This increased connectivity has spurred a quest for high capacity communication systems that must now overcome the fundamental capacity limit set by noise and nonlinear effects in single mode fibers. In this context, spatial division multiplexing (SDM) is currently emerging as the next wave of optical communication systems, allowing capacity scaling by orders of magnitude. SDM relies on transmissions of orthogonal modes in few mode fibers (FMF), sometimes in combination with a multi-core approach. A family of modes that could be used to decrease cross-talk in SDM links, and reduce digital signal processing requirements, is the family of modes carrying orbital angular momentum (OAM modes). Contrary to traditional LP modes that are degenerate combination of vector modes, OAM modes correspond to true fiber eigenmodes.

In this talk, we will review the properties of OAM carrying modes in optical fibers. An important performance indicator in these fibers is the effective index difference between vector modes of a given mode group. We will describe three designs of OAM fibers to maximize the effective index difference and the number of OAM modes. The first one is an inverse parabolic graded index fiber (IPGIF) that supports six OAM states in addition to the fundamental mode. We will describe characterization results using FBG writing to measure index change. We will discuss efficient OAM mode excitation, present loss measurement results and discuss transmission in a 1 km fiber length. The second fiber has a ring index profile with a hollow central section that supports up to 36 OAM states. Finally, the third fiber design has a similar ring index profile but it is an all silica fiber (without holes). We discuss trade-offs in the number of modes, effective index separation and propagation loss in these ring designs.  

 

Lastly, we will briefly present the Center for Optics, Photonics and Lasers (COPL). We will describe its fiber fabrication facility and the testbeds of the optical communication laboratory. We will discuss opportunities for collaboration, student exchange and graduate studies.