Performance of Birefringent Launching Fibers for Reducing Polarization Noise in Optical Time Domain Reflectometry


IEICE TRANSACTIONS (1976-1990)   Vol.E71   No.3   pp.218-223
Publication Date: 1988/03/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Communication Cable and Wave Guides

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A short birefringent launching fiber is proposed to reduce the fluctuation of backscattering from single-mode fibers. The fluctuation is due to polarization-sensitive measurements. It is analyzed that the polarization direction of linearly polarized inputted light is required to make an angle of 27.4 with respect to the principal axes of the birefringent launching fiber. It is also clarified that degree of coherence should vanish at the group delay of τ and 2 τ where τ is the group delay difference of the orthogonal polarization modes in the birefringent launching fiber. Experiments reveal that the birefringent launching fiber of only 3-m length makes it possible to reduce the backscattered power fluctuation to less than 0.05 dB. Required properties of laser diodes are discussed by considering the coherency of the laser diodes with multi-longitudinal modes.