Absolute Polar Duty Cycle Division Multiplexing: A Spectrally Efficient Multiplexing Method

Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) is a new multiplexing technique, which is based on absolute Polar Return-to-Zero (RZ) duty cycles, that increases the channel count from the conventional multiplexing techniques. Absolute Polar Duty Cycle Division Multiplexing over Wavelength Division Multiplexing (WDM) is a multiplexing technique which promises better spectral efficiency. It faces nonlinearities such as Self Phase Modulation, Cross Phase Modulation and FourWave Mixing, which affects the spectral efficiency. FWM is the prominent nonlinearity faced by AP-DCDM system. RZ and NRZ modulation schemes are used to evaluate the performance parameters of AP-DCDM system. The RZ format would be beneficial for systems with few channels but would require NRZ as the number of channels increase. The RZ format has better baseline receiver sensitivity when the average power into the fiber is kept constant. Since an RZ pulse has a wider optical bandwidth than an NRZ pulse, it is more affected by dispersion. In AP-DCDM system, with the change in duty cycles and polarity of each RZ pulses, error detection and correction is possible at the receiver side. AP-DCDM system has high spectral efficiency and tolerance towards dispersion due to its reduced spectral bandwidth. The performance analysis of the system is done by using Optisystem 12.0 software.