<title>Feedback noise in single-mode semiconductor lasers</title>

Abstract

In nearly every application of semiconductor lasers some externally reflected light is coupled back into the laser with a certain time delay. The noise and coherence properties are very sensitive to optical feedback. Coupling to external cavity modes induces frequency shifts, line-narrowing and broadening, competition among different external cavity modes, or dynamical instabilities. Strongly dispersive gain makes instabilities efficiently generate phase noise, leading to coherence collapse. We present an overview of these phenomena and their theoretical descriptions.

<title>Nonlocking behavior of an optically injected diode laser</title>

“…Using (3,4) in (1,2) yields (with n(t) = N(t) -N0 which we will call the inversion from now on, and with E(t) = E(t)exp [iwot]): (5) ñ(t) = -( + 0) n(t) -( + n(t)) (P(t) -P0) (6) In (6), P(t) = E(t)12 represents the actual photon number in the active medium. To gain more insight in th' dynamical properties described by these equations, it is instructive to consider the time-derivative of (6), wich can be written as:…”

“…This effect together with the phase-amplitude coupling, must be held responsible for the rich structure of dynamical instabilities which have been found in various applications of semiconductor lasers involving external perturbations such as current modulation, optical feedback, and optical injection [1], [5].…”