Coherence of a Laser Beam Passing through an Optical Fibre
作者:
Hikaru Takahara,
期刊:
Optica Acta: International Journal of Optics
(Taylor Available online 1982)
卷期:
Volume 29,
issue 4
页码: 441-453
ISSN:0030-3909
年代: 1982
DOI:10.1080/713820880
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The coherence of a laser beam passing through multimode fibres shows considerable variation. Experiments have been carried out in order to investigate this variation. The visibility of interference fringes is taken to be a measure of coherence. A He-Ne laser (632·8 nm wavelength) was used, with a multimode step-index fibre, a multimode graded fibre (Selfoc fibre) and a single-mode step-index fibre. The azimuthal angle of polarization and the degree of polarization of a beam passing through a single mode fibre show little variation compared to a multimode fibre. The visibility of interference fringes produced by two beams passing through either one or two single-mode fibres have an extremely small variation compared to the multimode fibre. The variation of the coherence of a beam passing through a multimode fibre is due to the superposition of different modes produced by the beams being transmitted. The value of visibility obtained by inserting a polarizer to get equal azimuthal angles of polarization is on the whole larger than that obtained without a polarizer. Another cause of the variation of the coherence of a beam passing through the multimode fibre is the different azimuthal angles of polarization produced by beams passing through one fibre.
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