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Since the invention of diode lasers in the early 1960's there had
been continuous investigations in laser diode pumped solid state
lasers as has been reviewed in detail by a number of papers
( see e.g. [1] ). There are two main advantages of using diode
lasers instead of flashlaraps as a pump source for solid state
lasers: First the emission of the diode lasers matches well with
the absorption bands of several Rare Earth ions that are doped in
laser crystals ( mainly Nd3+, but also Er3, Tm3, Dy3', and
others ) . This summary will report only about diode lasers at a
wavelength of around BlOnm, which fits to an absorptionband of
Nd3t Second diode lasers provide the possibility of
longitudinally pumped configurations and therefore an excellent
mode matching with the solid state laser mode. For both reasons
the efficiency of a diode laser puniped solid state laser is nuch
higher than of a flashlamp pumped one.
Since the early 1980's a much wider interest in diode laser
pumped solid state lasers arose. It was stimulated by the
improved performance of the new generation of diode lasers in
terms of reliability , operational lifetime and output power [21.
Two important steps in direction to the diode lasers at present
time were the developments of double hetero (DH) structure- and
graded index separate confinement hetero (GrInSCH) structurediode
lasers. In the same way the development of new production
techniques were necessary to ensure the reliability of the diode
lasers. Starting with the liquid phase epitaxy (LPE) the (GaAl)As
structures are now grown by the molecular beam epitaxy (MBE),
mainly used for very high precision laboratory investigations,
and metal organic chemical vapour deposition (MOCVD), mainly used
for commercial production.
As a first commercial product SDL introduced a 100mW array in
1984. Since then the output power of the commercially available
diode lasers increased by two orders of magnitude to lOW. These
diode lasers are multi stripe bar arrays like the 5W diode laser
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