Tunable Lasers What is a Tunable Laser ?
128 Agilent 8163A/B, 8164A/B & 8166A/B Mainframes, Sixth Edition
The Analog Output
If there is an output BNC connector on the front panel of your Tunable 
Laser module, you can output a DC voltage level that is proportional to the 
laser output power. The relationship between this voltage level and the 
output power is not calibrated.
Figure 67 Output Power and the Analog Output in <Manual ATT.> Mode
Attenuator
If your Tunable Laser module has an attenuator installed, the Analog 
Output signal depends on the power mode you have chosen. The voltage 
level is proportional to the optical power produced by the laser diode (not 
the optical output power).
In <Manual Att.> Mode, the relationship between the power value, [P], 
and the voltage level is only proportional to the output power if the 
attenuation remains constant. The attenuator adds a constant offset to the 
voltage level.
In <Automatic> Attenuation Mode,  the laser output power, and therefore 
the Analog Output signal, is not linearly proportional to the output power. 
This is because the actual output optical power is derived by the optimum 
combination of the laser output power and the attenuation. 
To set the power to −10 dBm:
1 Move to power parameter, [P], and press [Pwr unit]. You should see the power 
unit menu.
2 Move to <dBm> and press Enter.
3 Press Enter to edit the power value.
4 Enter −10.000 and press Enter.
Voltage, V
[P], mW
5 V
20 mW
2 mW
[A
TTEN.] = 0 dB[ATTEN.] = 10 dB