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C AUTI O N
Tunable Laser Sources
How to Modulate a Signal
Figure 5-14 shows how a TTL-level input signal modulates the
optical output. Digital modulation sets the frequency of the output
signal.
To set the amplitude of the output signal, set the power parameter.
This is the maximum output power of the output signal; at the
minimum output power, no power is output.
To enable external digital modulation:
1 Move to the Tunable Laser channel and press [Details].
2 Move to [M
3 Move to <E
press E
NTER
channel.
External Analog Modulation
External analog modulation uses a signal of up to 5 V
signal causes 15% modulation of the power of the optical signal.
Apply this signal to the input BNC connector on the front panel of
your Tunable Laser module.
There are two BNC connectors on the front panel of the HP 81680A,
HP 81682A, and HP 81640A - a BNC input connector and a BNC output
connector.
There is one BNC connector on the front panel of the HP 81689A - a BNC
input connector.
An absolute maximum of ±6 V can be applied as an external voltage to any
BNC connector.
119
S
] and press E
OD
RC
NTER
D
>. by using the cursor key, and
XTERNAL
IGITAL
. The text ExtD appears in the Tunable Laser
.
. A 5 V
pp
pp
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