laser spot) [85], and a value (averaged over a 1.5 mm spot size) of 120–140 K
above room temperature was measured.
This CMD most often happens at the facets, as they are not well cooled, have
the highest current density, highest optical field [86, 87], and usually some
parasitic additional heat source (defects, mirror coating) which triggers the thermal
runaway. Traditionally, the whole mirror was blown off, stopping the laser to
work because of the damaged optical cavity, therefore called catastrophic optic
mirror damage (COMD). Because of an improved thermal design, the junction can
often melt only microscopically, without any visible defect under the optical
microscope [88]. Nevertheless, the diode laser stops working since the molten
and re-crystallized ...