Home Forums SYSTEM Direct Modulation of LASER

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    • #39222
      Abhilash Achanta

      I am trying to directly modulate a LASER using a 10 Gbps digital signal.
      The LASER component is of type ‘Directly Modulated LASER measured’ type.

      In the LASER’s properties I have set rise time as 0.35 ns. This means that the LASER can be modulated upto 1 Gbps.
      Beyond 1 Gbps, the output should get distorted.

      But, when I simulated using OptiSystem the LASER could be pass almost all frequencies without any sort of distortion.

      Does rise time parameter have any effect at all on the modulation speed?

      Please find attached screenshots of
      -Layout and
      -Electrical and optical signal graphs at 100 Gbps direct modulation

    • #39312
      Karan Ahuja

      Can you specify what are you exactly designing.
      I am not getting how setting time affects the data rate. Please explain a bit.
      Thank you

    • #39325
      Abhilash Achanta

      Hi Karan,

      The Laser’s rise time is the time required for laser output from 10% to 90% of total power.

      Rise time is a factor that decides the 3db Bandwidth of the Laser. ( risetime = 0.35/BW )

      So, for rise time = 35 ps. The BW = 1 Gbps.

      In the layout attached, I directly modulated the Laser above 1Gbps and the output of laser showed absolutely no distortion.

      I tried this with the analog signals also, but the result is the same.

    • #39356
      Damian Marek

      There does seem to be a problem with the Laser when operated in Analog configuration mode. I recommend switching it to Digital configuration in the main tab. It should function properly now. The difference being in digital configuration the input is normalized to a range of amplitude from 0 to 1.

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