| 摘要 |
PHN 12.836 15.12.1989 Optical coherent receiver. An optical coherent receiver comprises means preventing radiation from the local oscillator (40) from being reflected in the transmission fibre (10). As a result this radiation, after reflection on imperfect couplings (11, 12, 13) in the transmission fibre, is prevented from reaching the receiver again and from detrimentally influencing the received signal. Reflection of local oscillator radiation is prevented by obliquely polishing entrance and exit faces of fibres (51, 52, 61, 62), by providing anti-reflection coatings (50', 60', 53', 54', 63', 64') on the appropriate faces and by arranging an optical isolator behind the input (20) of the coherent receiver. (Figure).
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