At the receiver end, direct detection (DD) is used to recover the modulated signal. The modulated optical signal is detected by a photodetector (most commonly PIN or APD photodiode), which converts the optical power variations into corresponding electrical current or voltage variations. The output of the photodetector is then processed and decoded to retrieve the original information.
At the receiver end, direct detection (DD) is used to recover the modulated signal The modulated optical signal is detected by a photodetector (most commonly PIN or APD photodiode), which converts the optical power variations into corresponding electrical current or voltage variations. The output of the photodetector is then processed and decoded to retrieve the original informati.on.