Flattened Optical Multicarrier Generation Technique for Optical Line Terminal Side in Next Generation WDM-PON Supporting High Data Rate Transmission

A novel and cost effective optical multicarrier (OMC) generator is introduced in this article. OMC is generated by connecting three modulators in cascade with laser source, where laser is connected with one amplitude modulator and two Mach-Zehnder modulators (MZMs) in cascade. The amplitude modulator is used for the first time in cascade configurations for the generation of OMC signal. All the modulators are driven by RF signal of 30 GHz where specially tailored or fiber-Bragg gratings are not required. The generated OMC is very flat due to the proper DC biasing of MZMs and being related to the optimum ratio of DC bias and half wave voltage of MZMs. OMC offers 61 comb lines with minimum excursions in its comb lines, having tone-to-noise ratio greater than 40 dB, frequency spacing equal to 30 GHz, and high side mode suppression ratio over 35 dB. In this configuration, no optical phase shifter, amplifier, or attenuator is used. Second, optical line terminal (OLT) costs of conventional wavelength division multiplexed passive optical network (WDM-PON) system are reduced by introducing the proposed OMC source at OLT side of WDM-PON system for large capacity WDM-PON that supports numerous users. At OLT side, each out of 61 carriers is capable of supporting 10 Gb/s differential phase shift keying based data in downlink transmission. In the uplink transmission, half power splitters are deployed at optical network unit (ONU) side, where half power of the downlink signal is utilized for uplink transmission based on intensity-modulated on-offkeying resulting in colorless ONUs. The detailed power budget is discussed for the validity of results. Bit error rate (BER), eye patterns, and power penalties lie in the metrics encountered for the analysis in full duplex PON's transmission. Minimum power penalties at specific BERs of different channels show the applicability of the proposed model.