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I was wondering if there was a difference between modulation frequency and rise and fall times of a laser diode or LED? If a laser had a modulation frequency of 100MHz would that be the same as a rise time of 5ns and a fall time of 5ns as 100MHz is equal to 10ns?

Thanks

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  • \$\begingroup\$ Do you ask for math facts what is the relation between frequency and rise and fall times or are you interested in how the light flow varies along the time when the input voltage or current waveform is known? \$\endgroup\$ – user287001 May 27 '19 at 11:13
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If a laser had a modulation frequency of 100MHz would that be the same as a rise time of 5ns and a fall time of 5ns as 100MHz is equal to 10ns?

No because if that was true the modulation signal would have the shape of a triangle wave.

If the modulation was a square wave then the rise and fall times would need to be much shorter.

If the modulation was a sine wave there would be no real rise/fall times.

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  • 1
    \$\begingroup\$ Ha ha ha, let me tell you about the latest IEEE Ethernet optical networking standards. With equalization and error correction becoming "cheap" we no longer need even 50 MHz to transmit a 100 Mbps signal (or rather, we no longer need even 25 GHz bandwidth to transmit a 50 Gbaud signal) \$\endgroup\$ – The Photon May 27 '19 at 14:32

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