Optical Multi-Wavelength Source for Single Feeder Fiber Using Suppressed Carrier in High Capacity LR-WDM-PON

In this paper, a novel cost-effective optical multi-wavelength generation scheme based on a pulsed laser and a single Mach-Zehnder modulator (MZM) is proposed. Over 50 wavelengths has been achieved with the proposed cost-effective scheme among which 37 wavelengths were selected for transmission because of their small amplitude excursions between the wavelengths and high tone-to-noise-ratio of over 40dB. Frequency spacing is kept at 12.5 GHz, where 10-Gb/s data-based differential phase shift keying (DPSK) modulation technique is utilized for downlink (DL) transmission across each wavelength in single feeder fiber (SFF) wavelength-division multiplexed-passive optical network (WDM-PON), and the results are examined for 25 and 50-km SFF. In SFF, uplink (UL) transmission can be impaired by Raleigh backscattering (RBS) noise. In this scheme, the RBS noise is alleviated at ONU side with the help of carrier suppression by utilizing non-return-to-zero (NRZ) dual port (DP) dual drive (DD) MZM modulation technique, where both the DL and UL transmissions are merged by using optical circulators without using a dispersion compensating fiber. At the receiver side, the signals are identified with the help of optical filters and divided in two halves using 1 × 2 forks, half of which is received and demodulated using DPSK receiver, whereas the other half of the transmitted signal is re-modulated with the help of a single 10-Gb/s NRZ-DP-DD-MZM modulation technique for UL transmission. Overall, 740-Gb/s data has been transmitted across 25 and 50-km bidirectional optical fiber for DL and UL transmission. The proposed scheme is analyzed in terms of bit error rate of 10e^-9, power penalties (PP), and eye diagrams (ED). It is found that the observed PPs are negligible, and wide openings of the EDs satisfies that the proposed scheme is worth consideration for deployment in long reach WDM-PON.