Spectra-Physics Tsunami - Modelocking the Laser

Tsunami Mode-Locked Ti:sapphire Laser
7-4
5. Adjust M
10
vertically for maximum power.
Did power increase or decrease compared to the power level measured
in Step 3? If it increased, repeat Steps 4 and 5, turning the vertical
knob in the same direction until power begins to drop. If it decreased,
turn the vertical tilt control in the opposite direction so that it increases
again and repeat these steps until output power drops again.
6. When the laser is optimized in the vertical direction, repeat Steps 3
through 5 using the horizontal controls.
7. If necessary, recenter the beam on M
10
. Carefully adjust M
3
(and M
4
and
M
5
if necessary), then adjust M
10
to maximize output power.
8. To recenter the beam on M
1
, carefully adjust M
2
. Then again adjust M
1
to maximize output power.
9. Repeat this entire procedure, starting at Step 3, until no further
increase in power is noted.
This completes the procedure for “walking the beam” to optimize laser out-
put.
Modelocking the Laser
Proceed to modelock the laser once the pump laser and the Model 3955 are
warmed up.
1. Push the STATUS mode locker enable button (the ENABLE LED should
turn on).
The two TEMPERATURE indicators on the Tsunami laser control panel
turn from red to green when the AOM and GTI (ps configuration) heat-
ers stabilize. Proceed to Step 2 when the indicators are green.
A flashing red indicator means either: (a) the GTI is not installed
(which is normal for a fs configuration) or (b) there is an unplugged
cable.
2. To measure the Tsunami output pulse width, use an autocorrelator such
as a Spectra-Physics Model 409-08, and avoid saturating the autocorr-
elator (refer to the autocorrelator manual).
For a brief discussion on autocorrelation and measuring pulse widths,
refer to Appendix B, “Pulse Width Measurement.”
Skip to Step 4 if you just optimized output power in the previous sec-
tion.
3. Maximize Tsunami output power.
Place a power meter in the Tsunami beam path and adjust
M
10
and M
1
for maximum output power.
4. Adjust the autocorrelator for maximum signal.
5. Adjust the mode locker fine
PHASE control for most stable pulse.
If laser output pulses are not present, adjust the fine PHASE control on
the Model 3955 electronics module until either a short pulse appears
on the oscilloscope or the autocorrelator signal is maximized.