Performance of two-level PAM and analogue PWM hybrid optical fiber transmission systems

We analyze the performance of optical fiber transmission systems using a 2-level pulse amplitude modulation (PAM) and analogue pulse width modulation (PWM) hybrid technique. The system performance is evaluated by considering the signal-to-noise ratio (SNR) of 50 dB for video communications and the bit error rate (BER) of 10/sup -9/ for digital communications as a lower bound. Optical receivers using both avalanche photodiode (APD) and PIN photodiode are considered. The minimum average optical power, which is required by an analogue-PWM signal to guarantee the 50-dB SNR at an optical receiver, is calculated, while the receiver sensitivity is analyzed for a 2-level PAM digital optical fiber system. The results show that the proposed system can perform better than the required lower bound.