Using of Split Step Fourier Transform Algorithm for Computing Error Probability Induced by Self Phase Modulation in Optical Signal

Increasing data rate in optical communication systems leads to nonlinear electromagnet phenomenon in optical signal along fiber, and causes distortion in it.Thefiber dispersion is a linear phenomenon that causes difficulties toachieve high bit rate and distance product.The limiting of nonlinear effects requireslow input power level, but this induces lowsignal to noise ratio. So, we search another solutions. This paper studies Split Step Fourier Transform Algorithm (SSFTM) used to solve partial differential nonlinear Schrödinger equation (NLSE).Then, we use it for simulating optical signal propagating in fiber by using MATLAB program, and designing fiber optic block could add it to MATLAB Simulink Library. Finally ,in this paper, we achieved results for selecting important parameters in single mode fiber for high bit rate, for improving bit error rate and Qcoefficient.

Study and analysis of the impact of noise on the receiver sensitivity in the digital optical communication system

The effect of thermal noise and shot noise on the receiver sensitivity in a digital optical communication system will be studied and analyzed. Also, the positive and negative effects of Parameters on the receiver sensitivity will be highlighted. The programming tools (MATLAB) is used to study the relationship between the receiver sensitivity and bit rate. It showed that the shot-noise-limited receiver sensitivity is much better than the thermal -noise-limited receiver sensitivity with best 30dB. The study also provided an explanation for the preference of optical detector (APD) compared to that in (PIN) optical detector from sensitivity side due to its internal gain, this can be achieved when the thermal noise is dominant. However, the preference of optical detector(PIN) will be better in case of shot noise is dominant. Analyzed results show that there is a significant improvement in the shot-noiselimited receiver sensitivity for high quantum efficiency and high wavelength. However, the sensitivity is deteriorated to get a lower error rate. The thermal -noise-limited receiver sensitivity showed an improving by increasing the responsivity and the load resistance. However, it decreases by increasing the number of noise and the error rate.