The influence of mode-coupling on the degree of coherence in an optical fiber

Abstract

The modulus of the complex degree of coherence across the exit face of a coherently excited optical fiber is investigated by taking account of coupling effects between propagating modes. We also discuss the results of numerical calculations for a quasi-single mode fiber. The modulus exhibits an oscillatory behaviour along the fiber length if coupling or beating is present. The oscillatory modulus is found to be large compared with the value it would assume if the cross-terms were neglected.