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The
nomenclature distinguishes between unmounted
and mounted laser diode bars. |
From
the functional point of view, the unmounted
laser diode bar (1) is a light-emitting
diode. |
With
one exception it meets all technical requirements
to be operated as a laser : In unmounted |
state,
no loss power can be dissipated. In this state,
operation of the laser diode bar is not |
possible. |
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The
ready-made diode laser module,
however, can be considered to be a radiation
source in
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the
sense of a ready-for-use component.
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In
different contexts, diode lasers of above
1W or above 10W
are termed as high-power diode
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In
this document, the term HDL is used for diode
lasers based on laser diode bars.
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Unlike
the single chips customarily used in the field
of telecommunications, so-called |
laser
diode bars are used exclusively. |
This
refers to all products and usually conicides
with the power limit above 10W.
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In
the following, the terms high-power diode laser
(HDL) and diode laser (DL) are used |
synonymously. |
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Operating
principle of a Laser Diode |
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On
a laser diode, the p-n junction
between two strongly doped n-
and p-materials represents
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the
active medium / PEUSCH/. When applying a forward
voltage approximately corresponding |
the
band gap at the p-n junction,
electrons and holes are being injected above
the p-n juction. |
The
narrow zone in which this inversion is generated
is called the active zone. If the forward |
voltage
is raised above the threshold voltage and appropriate
semiconductor materials are used, |
e.g.
GaAs, the probability for a
radiating recombination is high. If there is
a sufficiently high |
concentration
of injected charge carriers, this will result
in an optical amplification. |
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The
crystalline end faces of the semiconductor form
the mirrors of the resonator. |
Diode
lasers exhibit a very high electro-optical efficiency
of nel.-opt. = 50%. |
Typically,
commerecially available wavelengths are 808nm,
940nm and 980nm. |
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