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 wavenumberdecreased), and o ut-
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 Bia s current
has to be done only by instructed personnel,
and after checking with Alpes Lasers SA for
allowedparameter ranges; o therwise 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
makesure that thermal ro ll-overis no t reached:
Temporaryincreasing of the pulse current must
always result in increased optical power out-
put, otherwise the DC Bias current is already
too high.