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If I want to DC bias the following laser diode it seems I need to use pin 3 with a current source (drawn in red by me) as follows:

enter image description here

Description of the pies are shown below:

enter image description here

There is no anode pin nor a ground pin.

The thing is, RF is the modulation input. But there are no dedicated pins for biasing. Let's say I connected the RF connector for modulation input. How will I then connect the bias current source?

enter image description here

edit:

enter image description here

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  • \$\begingroup\$ Your diagram shows pin 3 as connected to an internal inductor. The specs show pin 3 going to the diode cathode. Which is correct? \$\endgroup\$ Commented Jun 20, 2023 at 23:24
  • \$\begingroup\$ They just call it cathode. The diagram is correct. \$\endgroup\$
    – ty_1917
    Commented Jun 20, 2023 at 23:48
  • \$\begingroup\$ Then there is a separate RF modulation connector, and pin 3, with internal inductor for DC bias? What is your question? \$\endgroup\$ Commented Jun 21, 2023 at 0:36
  • \$\begingroup\$ Pin 3 is a "dedicated pin for biasing". \$\endgroup\$
    – The Photon
    Commented Jun 21, 2023 at 2:30

1 Answer 1

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But there are no dedicated pins for biasing.

Pin 3 is a dedicated pin for biasing.

How will I then connect the bias current source?

That depends on the design of the bias current source.

It's somewhat likely that the current source would be connected to some negative power supply circuit, and that power supply circuit would need to be referenced to the RF ground.

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  • \$\begingroup\$ Hello thank you for the answer. I made some drawings to be sure here: i.sstatic.net/cx2zV.png I understand what you mean in the case of a voltage resistor current source as in Figure 1. But if I use a current source module as in Figure 2 how will be the connections? Positive terminal of the power input will be connected again to the RF ground? Where will the LD- terminal be connected? \$\endgroup\$
    – ty_1917
    Commented Jun 21, 2023 at 16:51
  • \$\begingroup\$ @ty_1917, can you share the datasheet for the current source? \$\endgroup\$
    – The Photon
    Commented Jun 23, 2023 at 5:15
  • \$\begingroup\$ The one I have is here 5A version: teamwavelength.com/download/Datasheets/pld10k-ch.pdf \$\endgroup\$
    – ty_1917
    Commented Jun 23, 2023 at 8:18
  • \$\begingroup\$ @ty_1917, follow figure 8 in that datasheet. For the laser diode's anode use the case of your laser module, for the cathode use pin 3. Don't connect the ground of your power supply (shown as "5 VDC" in figure 8) to the laser case/rf ground. \$\endgroup\$
    – The Photon
    Commented Jun 24, 2023 at 5:30
  • \$\begingroup\$ Do you mean this way: i.sstatic.net/JKx0V.png ? \$\endgroup\$
    – ty_1917
    Commented Jun 24, 2023 at 14:13

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