The influence of feedback intensity on longitudinal mode properties and optical noise in index-guided semiconductor lasers

Abstract

Theory and experiments on optical feedback effects in index-guided single-mode semiconductor lasers are presented. Evidence is found for the existence of a characteristic parameter <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</tex> which indicates the relative strength of the optical feedback. Near the transition ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C \approx 1.0</tex> ) from low to high feedback, the feedback-induced low-frequency intensity noise shows a maximum. At higher feedback hysteresis and instabilities are dominant, whereas the feedback-induced noise is low again.