Tsunami Mode-Locked Ti:sapphire Laser
7-12
seen through M
8
. Once unit lases, optimize the output as you would
normally.
16. Install the slit assembly.
a. Close the shutter.
b. Place the tuning slit assembly into the laser head and onto the
micrometer shaft. Refer to Figure 6-8.
c. Rotate the slit width adjustment screw until the dowel pin on the
mating shaft can slide into the slot.
d. Seat the slit assembly against the micrometer stop.
e. Tighten the setscrew.
17. Open the shutter and verify the beam is still centered on M
4
, M
5
and the
OC.
18. Adjust the pump focus as you would normally for maximum output
power.
With 5.0 W of pump power, the Tsunami should output between 650
and 900 mW.
19. Adjust P
1
and P
4
so that the beam passes through the very tips of these
prisms.
Since the system design requires very little positive GVD compensa-
tion, it is critical that the smallest amount of glass possible is inserted
into the beam. Ideally, the prisms should be adjusted so that about
20 mW per prism is lost over the tops of the prisms.
20. Turn down the pump power so that Tsunami output power is between
300 and 350 mW.
21. Install a spectrum analyzer or other bandwidth diagnostic tool to mea-
sure the laser output.
22. Turn on the mode locker and adjust
P
2
and P
3
counterclockwise until
the system modelocks.
23. Adjust P
2
and P
3
and vary the pump power to achieve at least 40 nm of
bandwidth at > 300 mW. When no more bandwidth can be gained by
adjusting the prisms, turn the slit micrometer counterclockwise for
maximum bandwidth.
24. Adjust the fine phase control to obtain mode locker-initiated pulsing.
The phase is much more sensitive in the sub-fs regime than in a stan-
dard system so the fine phase control must be used.
25. Verify the Tsunami tunes from 750 to 850 nm.
26. Gently tap on various mechanics and press on
M
6
through M
9
to verify
laser does not detune.
To avoid damaging nearby optics when installing the slit, carefully
move it into place and use your hand to support it while you tighten the
mounting setscrew.
Warning!
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