Spontaneous Generation of Spiral Modes due to Evanescent Coupling between Two Optical Fiber Ring Arrays

Hiroyuki YOSHIDA   Noriaki TSUKADA   

Publication
C - Abstracts of IEICE TRANSACTIONS on Electronics (Japanese Edition)   Vol.J92-C   No.6   pp.204-209
Publication Date: 2009/06/01
Online ISSN: 1881-0217
Print ISSN: 1345-2827
Type of Manuscript: PAPER
Category: 
Keyword: 
optical fiber ,  evanescent coupling ,  circular fiber arrays ,  discrete coupled wave equation ,  spiral modes ,  

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Summary: 
We investigate coupling dynamics between two circular optical fiber arrays by use of the discrete coupled wave equations. The calculations are performed with the periodic boundary phase conditions (one round accumulation phase of the arrays is to be 2π integers). The numerical results show that when the relative phase difference between two arrays is given by 0, 2π, and 2πm, a stationary mode, a single spiral mode, and a m-fold spiral mode are induced, respectively. Furthermore, it is shown that the rotational direction of the spiral modes depends on the coupling strength between two fiber arrays, the rotational velocity of the spiral modes depends on the nonlinear coefficient, and the conversion from the stationary mode to the spiral mode occurs due to the nonlinearity. The phenomena shown in this report give an optical beam steering technique and must be useful to fabricate optical divider and optical combiner.