Pigtailed Laser Mount
Chapter 5: Operation
Rev C, September 5, 2018
Page 15
Operation
5.1. General
Once the laser is mounted in the LDM9LP and a Laser Diode Current Controller
and TEC Controller are connected, the device is ready to operate. Please refer to
the operating instructions for the laser and temperature controller for specific
operating instructions.
When operating at low temperatures in high humidity climates, the laser mount
may develop internal condensation. If this occurs, turn the laser off, open the
case, and allow the mount to dry off completely before reusing.
5.2. RF
Modulation
The LDM9LP has an RF input for modulating the laser with an external RF
source from 200 kHz to beyond 1 GHz. This is a 50
Ω
input that is AC-coupled
directly to the laser through the Bias-T network. To calculate the desired RF
power to modulate the laser, determine the amount of modulating current needed
from the laser manufacturer’s data sheets and use the following calculations:
50 Ω
It is strongly recommended that you start off conservatively by a factor of 10
below the calculated modulating voltage and slowly bring the RF power up until
the desired depth of modulation is reached.
Use the laser controller to establish the DC operating point of the laser.
WARNING
The RF input is directly coupled to the laser. Any excessive transients or noise will
be coupled into the laser and may cause the laser to be overdriven. Also, the laser
can be easily overdriven if excessive RF power is applied to this input. Use the RF
modulation input with care to avoid damaging your laser.
