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I'm using a photodiode module, model: coaxial InGaAs, Gtel.

I set it in reverse bias with 5V and tested it with a laser but it doesn't give any output voltage. Unfortunately I don't know the laser wavelength. The resistor in this circuit is 5k.

I have 3 of these modules but none of them worked.

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  • \$\begingroup\$ Can you see the laser? If you can see the laser then it is below 700nm and your photodiode can only see 900-1650nm. \$\endgroup\$
    – DKNguyen
    Commented Dec 26, 2019 at 18:51
  • \$\begingroup\$ Try it with 2LED's. One as an LED emitter and 1 used as a Photo diode. See if you can get that to work. Allow 1~10uA leakage. \$\endgroup\$
    – D.A.S.
    Commented Dec 26, 2019 at 20:57
  • \$\begingroup\$ Find a laser with emission above 900nm and test again. \$\endgroup\$
    – user1850479
    Commented Dec 27, 2019 at 6:02
  • \$\begingroup\$ @DKNguyen No, I'm sending laser through optical fiber. I will check it. \$\endgroup\$
    – sepehr
    Commented Dec 27, 2019 at 13:46
  • \$\begingroup\$ @Tony Stewart Sunnyskyguy EE75 sorry I have not got your idea. Could tell me more simple? \$\endgroup\$
    – sepehr
    Commented Dec 27, 2019 at 13:48

2 Answers 2

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In reverse biasing the current will be very small (single uA to hundrets of uA level, it means tenth of mV on 5k), additionally - if you are out of optimal wave length, the sensitivity can be much less than shown in datasheet. Probably this is the reason that you can't see any output. So: try to increase RL to 50...100k or more (500k).

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  • \$\begingroup\$ I will check it and give you feedback. \$\endgroup\$
    – sepehr
    Commented Dec 27, 2019 at 13:50
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I set it in reverse bias with 5V and tested it with a laser but it doesn't give any output voltage.

Photodiodes are current devices, they are to be used with transimpedance amplifiers (https://en.wikipedia.org/wiki/Transimpedance_amplifier), which translate current into voltage, which could be measured with eg. oscilloscope.

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    \$\begingroup\$ With a transimpedance amp they are faster and more linear, but they work ok with a resistive load. \$\endgroup\$
    – John Doty
    Commented Mar 23 at 14:51

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