Measurements of modal noise in single- mode lightwave systems

Abstract

Modal noise can be introduced in single-mode fibers with depressed-index cladding by the time varying interference between the LP01 and LP11 modes.1 The purpose of this study was to measure the modal noise in actual lightwave systems and to provide a model for properly choosing the fiber cutoff wavelength λc that reduces the noise to an acceptable level. Noise measurements were made using regenerators at 90, 420, and 1700 Mbit/sec.