Direct Modulation of LASER

[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?

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

[Karan Ahuja]

Hi.
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

[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.

[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.

[Author]

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