Datasheet

Chapter 4
Operating QCLs in continuous wave
mode
For electrical properties, see ”Chapter 2, p 8, Electrical properties”.
4.1 Thermal properties
The dissipated heat of a QC laser operated in CW mode is in the range of some Watts
(operating voltage in the 8V...12V range, current in the 0.5A...1.5A range). Keep in
mind that in general, the impedance of a QCL is decreasing with temperature!
4.2 Modulation of a CW mode operated QCL
To modulate a CW operated QCL (e.g, to sweep its emission), there are two possibili-
ties.
4.2.1 Direct modulation of the DC source
If your DC supply allows for this, you should directly use its control input to change the
output current (in the specifications given by the datasheet of course). Please make
sure that its bandwith is sufficiently high for your application.
4.2.2 Additional modulated supply
If your DC supply cannot be modulated (or not fast enough), you will have to add an
additional modulated source, e.g, a waveform (ramp) generator. Alpes Lasers SA does
not supply such generators nor the needed interfacing, but in the following, a scheme
for setting up the interfacing is explained which has proven to work. Please refer to the
drawings shown.
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