OEM Laser Diode Driver
Chapter 5: Operating the LD2000R
Rev I, May 21, 2018
Page 13
1. If the PWR Limit control is set below the maximum output power, the laser
output will plateau (clip) at the PWR Limit level for modulations below the
PWR limit.
2. If the total feedback gain, RF, is not optimized for the operating laser, the
laser turn off point of the output will be different than 2.5V (usually
somewhere below 2.5V since the default feedback gain is usually too high
for most lasers).
3. If the feedback gain is too low for a laser (i.e. the maximum laser power
can be reached at a point somewhere below the maximum setting of
PWR Limit, than use care to set the PWR Limit control to the maximum
desired operating power before applying the modulating voltage.
The turn-off
voltage is
dependent on
matching R
fext
to
the laser. If the
feedback gain is
too high, the laser
will turn off at a
lower voltage
(V
off
= R
F
(I
Mon
),
where
RF=R
F EXT
in parallel with
20 k
Ω).
Clipping due to
Current Limit
being set too
low.
