Patent ID: 7668216

Claim:
A method of coherence reduction for a laser diode having a laser wavelength λ which varies in dependence upon a drive current J of the laser diode, the method comprising: periodically modulating the drive current J of the laser diode within a current modulation interval (J min , J max ) between a minimum drive current J min and a maximum drive current J max using a modulation function J(t), wherein t represents time, wherein said modulation function J(t) is characterized by a greater slope at the edges of the current modulation interval (J min , J max ) than in the middle thereof, so as to provide laser radiation with an optical spectrum having a Gaussian-like shape when averaged over at least one modulation time span that is defined as a time interval wherein the modulation function J(t) varies between J min and J max , wherein an average value of the slope of the modulation function J(t) at the edges of the current modulation interval (J min , J max ) computed by averaging over the first 5% and last 5% of the modulation time span is more than two times greater than an average value of the slope of the modulation function J(t) in the middle of the current modulation interval (J min , J max ) computed by averaging over a center third of the modulation time span.