Analysis the Speciality of Modulation Format in WDM-PON System

In the wavelength division multiplexing passive optical network (WDM-PON) system, the modulation format was important. While three different modulation formats including not-return-to-zero (NRZ), return-to-zero (RZ), carrier-suppressed return-to-zero (CS-RZ) and the optical differential quadrature reference phase shift keying (DQPSK) modulation format of each code are introduced in the article. A method of their modulated signal generation with computer is described, and a comparison of their spectra and waveforms is made. The 40 Gbps signal transmitted in 200 km G.652 fiber by way of single channel with erbium-dope-fiber-amplifier (EDFA) is simulated for these three formats. It is showed that the ability of antidispersion and anti-PMD (Polarization Mode Dispersion) is better in the CS-RZ-DQPSK modulation format, and this format has the smallest eye-opening penalty with a wider range of power into the optical fiber.