Quantum Instruments Cascade Laser Starter Kit - Manual (Page 59)

Starter Kit Instruction Manual Appendix 58
• As a rule of thumb, the overall dissipated power
(sum of DC Bias current dissipation and pulse
current dissipation) must never be higher than
the average dissipated power given by the high-
est current / voltage / temperature combina-
tion specified in the datasheet.
Take into account that the average dissipated
power for a given pulse current I, pulse voltage
U, and duty cycle d is given by d x I x U,
whereas the dissipated power due to a Bias
current IB is given by IB x U. (U is the voltage
on the laser, but it is safe for this calculation
of Bias current dissipation to use the voltage
on the LDD pulser input.)
Current and voltage ranges of the Bias-T cir-
cuit
Since the input stage of the Bias-T is a bipo-
lar transistor, applied voltage must be higher
than about 0.6V to start Bias current. The in-
put stage has maximum voltage limit of 2.6V,
but the laser itself may be destroyed at lower
Bias-T control voltage already, therefore the
maximum rating has to be checked with the
abovementioned rules and together with Alpes
Lasers SA.
The monitor output (if available) allows mea-
surement of applied DC Bias current: Its volt-
age divided by 10OΩ gives Bias current. In
general, Bias current can be in the range of
0.1A, but this must be checked with Alpes
Lasers SA before.
CAUTION !
Avoid reverse polarity on the input!