Tektronix OM4006D, User Manual

Page: 39 / 205

Getting started
so that while the modulating frequency, f
n
is still the same, the frequency deviation,
f
D
, has been reduced by 2 π f
n
∆ t where ∆ t is the time difference for the two paths.
Some lasers can have frequency deviations in the 200 MHz range over 1 ms. To
minimize the FM bandwidth after detection, reduce the frequency deviation to ~
1 kHz. This is accomplished with
∆ t = 0.8 ns or a path difference of 16 cm or less.
Generally speaking the ET performance will be best with a path difference less
than 10 cm when possible. For lower noise lasers, path lengths differences up to
2 m can be tolerated.
Connections Make connections in the following order:
1. Ethernet connections and other computer connections
2. Power cord from the OM4000 instrument to the mains AC connector or to
the instrument rack (if used)
3. Power cord from rack (if used) to mains (keeping main front panel switch off)
4. RF connections (the four coaxial cables from OM4000 instrument to the
oscilloscope)
5. Fiber optic PM patch cable connection from Laser 2 to Reference (if needed)
6. Fiber optic Signal input connection
NOTE.
Turn off laser optical outputs before attaching cables.
Store all dust covers and coaxial connector caps for future use. Keep dust and
coaxial connectors installed on all unused instrument connections.
Power on the equipment and start applications:
1. Controlling PC
2. Oscilloscope
3. Scope Service Utility (SSU) application after the oscilloscope completes its
power-on cycle
4. OM4000 instrument
When powered on, the OM4000 front-panel power button will light brie fl y after
main power is applied, indicating it is searching for a DHCP server, and then tun
off. Press the power button one time to enable the unit. The steady power button
light indicates the instrument is ready for use and that lasers can be activated
using the appropriate controller software.
OM4000D Series Coherent Lightwave Signal Analyzer 15