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OPT3101: questions regarding using a laser diode as light source for OPT3101

Stani Bell Ngoufack Tchoufack89
Intellectual 2020 points
Part Number: OPT3101

Hello,

i'm currently planning to use the OPT3101 in a project and i have a few questions i would appreciate you can answer.

  1. What are the key care abouts if i decide to use the D650-5I laser diode (datasheet: https://media.digikey.com/pdf/Data%20Sheets/US%20Lasers%20PDFs/D6505I.pdf) as a light source for the OPT3101?
  2. Chapter 7.3.6 of the OPT3101 datasheet states that there is a "DC-bias current option" available. Is it possible to use this option to setup the "Threshold current" of the laser diode? or must i use a seperate laser driver on the output of OPT3101?
  3.  To make sure the laser is emitting with a power corresponding to a laser class 1, then i think a laser driver on the output of OPT3101 that monitors the laser diode might be needed. What requirements (Bandwith, linearity, impedance...) does the OPT3101 impose on a such laser driver? 

Your help will be mostly appreciated and will enable me to use the OPT3101 in my design.

Best regards,

Stani

  • 0
    TI__Mastermind 25845 points
    Hi Stani,

    1. Eye safety will be important for laser diode. Everything else will be dependent on your application and similar to the LED care-abouts covered in the system design doc and the simulator tool resources.
    2. Yes you can used the DC option
    3. The only requirement from the OPT3101 is that the laser or laser+driver is able to give a 10MHz square wave output optically

    Best,

    Alex
  • 0 in reply to Alex Bhandari-Young
    TI__Intellectual 2020 points

    Hi Alex,

    thanks for you reply. I have some further questions i hope you can answer:

    1. You confirmed that we can use the "DC-bias current option" to set up the threshold current of the laser diode. Chap 7.3.6 of the OPT3101 datasheet states DC-bias (max) = 7.5mA whereas D650-5I needs a threshold current of 15mA. I researched for a 650nm laser diode with a threshold current of 7.5mA or lower and couldn't find any. Is there any 650nm laser diode you could recommend that has a threshold current of 7.5mA or lower? 

    2. Could you please share details of a laser diode driver IC/circuit that could be used to drive the D650-5I so that it can work with the OPT3101? 

    Best regards,

    Stani  

  • 0 in reply to Stani Bell Ngoufack Tchoufack89
    TI__Mastermind 25845 points

    Hi Stani,

    Unfortunately I cannot provide much guidance in terms of choosing a laser diode and driver. Since OPT3101 is an AFE (analog front end) any laser diode that can be driven at the 10MHz required by the OPT3101 at the needed threshold current should work. If they need to choose a driver they will have to verify that it can properly drive the diode at 10MHz.

    Best,

    Alex