Thermal noise in optical fibers and its influence on long-distance coherent communication systems

The theory of phase noise caused by thermal fluctuations in an optical fiber is revised, accounting for both longitudinal and transverse phonons, and for the anisotropy of the elastooptic effect. A realistic optical mode field is accounted for. The theory is applied to calculations of bit error rates in DPSK coherent fiber-optic communication systems. Numerical results show that the thermal phase fluctuations are unimportant for transmission distances below 10000 km.<
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