Maximum intensity noise induced by multiple-path interference from fiber-connector reflections

Abstract

A concept of Post-fiber-transmission Intensity Noise or Interference Intensity Noise (IIN) is proposed and a formula estimate of maximum Relative Intensity Noise (RIN) for a CATV system induced by laser phase noise and multiple-path- interference (MPI) from fibre-connector reflections has been given out through theoretical analysis and experiment measurement. It is turned out that maximum RIN increases with total number of unqualified connectors and their light reflection coefficients, but decreases with RF frequency increase. For a fixed-length fibre jumper ended with two unqualified connectors, there exists a worst RIN dependent on laser linewidth and RF frequency, also exists another worst RIN dependent on RF frequency and fibre length for a given laser linewidth. It is concluded, only from the point view of depressing RIN induced by connector reflections, that lasers having linewidth within 30-300 MHz had better not be used. Furthermore if no connectors with slant connective end-surface can be got at hand, very limited total number, less than about 4 for example, of fibre connectors with flat connective end-surface can be unquestionably used.