Tsunami Mode-Locked Ti:sapphire Laser
7-10
5. Verify the beam is in the center of M
10
, and adjust M
5
if necessary.
6. Again, refer to “Optimizing Laser Output” earlier in this chapter to
“walk the beam” and optimize laser output.
7. Adjust the bi-fi for the desired wavelength.
Purge the system with clean, dry nitrogen gas when you are operating
within water and oxygen absorption regions (Figure 7-1).
8. Push the STATUS mode locker enable button (the ENABLE LED should
be on).
9. Set up an autocorrelator such as the Model 409-08 according to its
user's manual, then maximize the signal by adjusting the angle of the
nonlinear crystal for the optimum phase-matching condition.
10. Maximize the intensity of the autocorrelated waveform by adjusting
the coarse and fine PHASE controls.
Refer to Chapter 6, “Alignment: Coarse Phase Adjustment...,” for
information on setting the coarse and fine PHASE controls.
11. Adjust the GTI POSITION control to obtain a pulse.
12. Optimize system performance by iterating between the following
adjustments:
a. Adjust the fine PHASE control.
b. Adjust the pump laser output power to obtain a stable pulse.
c. Adjust the GTI POSITION control for the desired pulse width.
Operating with the Ultrashort Pulse Option (USP)
The USP option allows operation of the Tsunami laser in the standard
wavelength region (720–850 nm) with < 50 fs output pulses. The basic
operation of the USP option with regard to pump power, Pr
2
/Pr
3
adjustment,
slit width adjustment, etc., is identical to laser operation in the standard fs
regime. However, the USP option uses prisms with a lower refractive index
which requires less glass to be inserted into the beam in order to produce
short output pulses.
Operating in the Sub-35 fs Regime
The following alignment procedure is provided for those persons interested
in operating their Millennia/Tsunami system in the sub-35 fs region. While
performing these steps, remember that it is a combination of pump power,
slit width, fold mirror position, and prism position that produces the maxi-
mum amount of bandwidth.
If you encounter problems while performing this alignment, refer to the
“Troubleshooting in the Sub-35 fs Regime” section that starts on page 7-
13.
1. Set the Millennia up for pumping a standard Tsunami. Make sure that
the Millennia is secure to the table and that its output beam is level to
the table.
To Next Page
Loading...