Quantum Instruments Cascade Laser Starter Kit - Manual (Page 58)

Starter Kit Instruction Manual Appendix 57
Dangers and disadvantages of using a Bias-T
circuit
• Since a Bias-T only allows to heat the laser,
the emission wavelength can only be increased
(or emission wavenumber decreased), and out-
put power will decrease with increased Bias
current, due to the additional heating.
This means that the laser should be operated
initially at lowest possible temperature
• Heating of the active zone will increase ther-
mal stress of the laser, therefore the expected
lifetime will decrease more rapidly compared
to increasing the temperature of the laser sub-
mount and base in total.
If operation at only a fixed wavelength is needed,
this should be adjusted with the overall tem-
perature control.
• Too high a DC Bias current can immediately
destroy the laser due to catastrophic thermal
roll-over. Therefore set-up of the Bias current
has to be done only by instructed personnel,
and after checking with Alpes Lasers SA for
allowed parameter ranges; otherwise warranty
will be lost.
What has to be kept in mind before use?
• All use of a Bias-T on a specific QC laser has
to be accepted by Alpes Lasers SA before;
otherwise all warranty will be lost.
• The Bias-T should never be used at the high-
est specified current or output power, other-
wise the risk of thermal roll-over failure is im-
minent.
• If optical output power can be monitored, this
should be used during set-up of the Bias-T to
make sure that thermal roll-over is not reached:
Temporary increasing of the pulse current must
always result in increased optical power out-
put, otherwise the DC Bias current is already
too high.