Multi-dimensional multi-level mode modulation with ultra-high spectral efficiency using higher order degenerate modes in optical fiber

2017 Fiscal Year Final Research Report

• Project/Area Number: 16K14264
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Communication/Network engineering
• Research Institution: Yokohama National University
• Principal Investigator: Kokubun Yasuo 横浜国立大学, 大学院工学研究院, 教授 (60134839)
• Research Collaborator: WATANABE Tatsuhiko ; KAWATA Ryo ; MIURA Seiya ; YAMAGUCHI Takuto ; TANAKA Makoto
• Project Period (FY): 2016-04-01 – 2018-03-31
• Keywords: 多次元変調 / モード変調 / 多値変調 / 固有モード / 光ファイバ / モード分析 / モード受信機

Outline of Final Research Achievements

To realize the multi-dimensional/multi-level modulation using orthogonal degenerate modes in few-mode fibers (FMFs), we proposed a novel high-speed mode detection method, which can obtain a full set of amplitudes, phases, and polarization states of guided modes including degenerate modes in few-mode fibers within the speed limit imposed by the response time of the electronics. The mode discrimination system using this method was developed in the first year.
In the second year, we observed the near-field patterns of light output from FMFs in which an LP (linearly polarized) mode was selectively excited. It was confirmed from the variation of the intensity profile with the wavelength that the true eigenmodes of a circular core fiber are guided in single-core step-index and graded-index FMFs. On the other hand, we discovered a new phenomenon that LP modes propagate as eigenmodes oriented along a specific axis in 4-LP mode 12-core FMF.

Free Research Field

工学，光エレクトロニクス