Average Intensity Distribution of Far-Field Radiation Patterns in a Multimode Optical Fiber

Masaaki IMAI  

IEICE TRANSACTIONS (1976-1990)   Vol.E63   No.1   pp.16-23
Publication Date: 1980/01/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Optical and Quantum Electronics

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Average intensity of far-field radiation patterns of laser light emitting from an end face of the multimode optical fiber is theoretically analyzed by assuming a Gaussian autocorrelation function for the refractive-index inhomogeneities in an optical fiber. The average intensity distribution of far-field patterns is characterized by both the statistical scale of index fluctuations and the fiber parameters of core radius and refractive-index profile. It is shown that the on-axis maximum intensity decreases as the correlation length of refractive-index inhomogeneities becomes small compared with the wavelength of light, whereas the off-axis average intensity decays gradually with the increase of the distance from the axis. The average intensity distributions obtained here are found to be nearly Gaussian for both types of the optical fiber with step-index and graded-index profiles of the refractive index.