reducing the impr oving efficiency and heat extra ction from t he active
region (asymmetric wave guide, see also Section 5.2) and by improved heat
sinking. In pursuit for highe r powers, some of these parameter s have b een
improved over the last few years and so have the s low-axis NA. Thermal wave-
guiding is still the major cause for NA degradation, and the remedy, an athermal
waveguide (i.e., m odal index does not depend on temperature), is still waiting to
be developed.
As with narrow stripe laser diodes, techniq ues have been investigated to
improve the slow-axis BPP by mode filters, most notably by taper lasers. The
bothersome destabilization of the slow-axis focal plane with resulting sensitivities
to drive current, reflections, and, possibly, ...