Question

A thermal-noise-limited PCM system must operate with an error probability better than 10^-9. The load resistance is 50 Ω and the temperature is 300 K. The data rate is 500 Mb/s (NRZ), the wavelength is 1.3 µm, and the photodetector’s quantum efficiency is 0.9. Please show your work to how you come up with the resutls.

1. What is the required minimum SNR?
2. How much optic power must reach the receiver?
3. Compute the number of incident photons per bit (that is, the number of photons when a binary 1 is received) at this power level.

Answer 1