Applies To These Products

WLD3343
WTC3243

Question

We would like to use the WLD3343 and WTC3243 to control a fiber-coupled laser diode which has laser diode anode ground. This ground is connected via the case to the thermistor ground. We are not using the photodiode, we scan through a range of currents to wavelength-tune the laser. When I look at your specification for the WLD3343, the picture on page 13 shows the laser diode anode connected to pin 14 i.e. 5 V. None of the other circuits show a grounded laser anode. Is the WLD3343 in fact compatible with an anode ground system? I’m worried because I can’t see how it can be, if its supply is 0 and 5 V, yet I need to connect the cathode to something less than 0 V.

Answer

The laser diode anode connected to Pin 14 on the WLD3343 will be connected to negative 5 V. Follow this link to a diagram that shows how to connect your particular laser to the WLD3343.
On the WTC3243, you will connect:

  • Pin 2 to the voltage setpoint
  • Pin 14 to the + side of your voltage supply (+5-30 V)
  • Pin 13 to the – side of your voltage supply (+5-30 V) and one side of your laser’s thermistor
  • Pin 12 to the + side of the thermoelectric in your laser
  • Pin 9 to the other side of your laser’s thermistor.

On the WLD3343, you will connect:

  • Pin 2 to the -voltage setpoint
  • Pin 7 to the – side of your voltage supply (-5-12 V)
  • Pin 11 to the cathode of your laser diode
  • Pin 14 to the anode of your laser diode and the + side of your voltage supply (-5-12 V).

If you do choose to use the photodiode, you will want to connect it as shown in the diagram.

  • The anode of the photodiode in your laser should be connected to RPD, with the other side of RPD connected to GND
  • The cathode of the photodiode in your laser should be connected to either the laser diode anode or the laser diode cathode.