HP 8167A, User Manual, Page: 50 / 262

2
The Modulation Output
The Modulation Output on the front panel outputs a version of the modulating
signal that has the same frequency and phase as the modulating signal, but has
a xed, TTL-level amplitude . Y ou can use this to synchronize your external
measuring equipment to the tunable laser source .
T o allow for your possible sychronization requirements , there are two ways
in which the signal can be output. Either the signal is combined with the
laser-ready signal, so that the output is kept low when there is no optical
signal being output (for example , while the laser is settling after a change of
wavelength). Or the modulation signal is output all the time . This is set by the
4
System
5
NNNNNNNNNNNNNNNNNNNN
MODOUT parameter (see \Setting the Modulation Output" in Chapter 3).
Example Set the frequency of the modulated output to 300Hz.
1. Press 4 OUTPUT POWER 5 .
2.
Press
N NNNNNNNNNNNNNNNNNNN
Mod/CW , and
N NNNNNNNNNN
Int if necessary , so that the display
looks as shown in Figure 2-9.
3.
Press
NNNNNNNNNNNNNN
Freq .
4. Type 300 on the numeric keypad.
5.
Press
NNNNNNNNNNNNNNNNNNNN
Hz/kHz , if necessary , to set the units to Hz, and press
4 ENTER 5 .
Using External Modulation
The external modulating source can be any signal of up to 5V
pp
. A 5V
pp
signal
causes 15% modulation of the power of the optical output signal.
Figure 2-10. External Modulation and Output P ower
2-12 Setting Wavelength and P ower