Performance of preamplified direct detection systems under influence of receiver noise

Abstract
We present new results for optically preamplified direct detection systems where the receiver thermal noise is significant. The results obtained with this model is in good agreement with measured results from a system experiment at 10 Gbit/s. It is found that an optical gain of 30 dB is sufficient to keep the penalty due to thermal noise below 0.1 dB for a simple receiver consisting of a photodiode loaded with a broadband amplifier with 50-/spl Omega/ input impedance.