Direct analog modulation of LED by Sinusoidal RF signal

[muhammad jawad]

Dear All
Hope you all will be fine
The direct analog modulation of a CW laser by Sinusoidal RF signal generates multiple coherent optical carriers/wavelengths. I would like to get know if we apply RF sinusoidal signal to a LED for its direct modulation, multiple coherent carriers generates or not???? I check but no carriers were generated. Please let me know if there is any way out
regards

[Ahmad Atieh]

Dear Muhammad,
if you directly modulate the LED with a sinusoidal signal, you get multiple tone at multiple of modulating frequency as shown in the attachment. However, the modulated light is not coherent.
Regards,
Ahmad

Attachments:

1. 

   directly-modulating-LED-and-LD_Jun-12-2019.png
   

[muhammad jawad]

can we use each of these equally spaced tones as separate carriers for data modulation like we previously used coherent carriers generated after direct modulation of LD by RF sine signal?

[Ahmad Atieh]

The signal is not coherent and too noisy. It will not go too far. You may filter it and try.
Regards,
Ahmad

[muhammad jawad]

thanks sir, i understood it fully

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