A spectral amplitude coded-optical code division multiplexing time division multiplexing （SAC- OCDM/TDM） passive optical network （PON） for upgrading the traditional TDM PON is proposed. To the best of our knowledge, our work is the first to report on the use of both spectral and orthogonal code domains, which are transparent to optical network unit （ONU） for hybrid PON, in order to upgrade TDM PON seamlessly. The fewer encoder/decoders and cheaper optical source under the conditions of high bite rate and large ONU accommodation make the system cost-effective. A downstream experiment is demonstrated, and the results demonstrate that the proposed system is feasible.
We propose and demonstrate a simple configuration of wavelength-tunable fiber laser made up of a tunable band-pass filter, a Sagnac loop refiector, and a Fabry-Perot laser diode. Based on the self-seeded operation, the proposed fiber laser can obtain a single-longitudinal-mode output in the wavelength tuning range of 1544.69–1563.39 nm with tuning step of 1.34 nm. The performances of output power （-9 dBm）, optical side-mode suppression ratio （ 65.5 dB）, and power and wavelength stabilities are well exhibited.
We propose a scheme for mitigating Rayleigh backscattering noise and demodulating differential phase- shift keying （DPSK） signals in wavelength-division-multiplexed passive optical networks （WDM-PONs） with injection-locked Fabry-Perot laser diodes （FP-LDs）. Signal demodulation and wavelength conversion are simultaneously realized on the basis of the frequency deviation and red shift of longitude modes in the FP-LDs. Experimental results demonstrate that the demodulation and wavelength conversion of 2.5-Gb/s DPSK signals are achieved. A power penalty of about 1.6 dB at a bit error rate of 10.9 is measured after transmission over 25-km single mode fiber.
We propose a novel wavelength-division multiplexed passive optical network （WDM-PON） to simultaneously transmit unicast data and multicast services with upstream data re-modulation in optical network units （ONUs）. For each wavelength channel in the optical line terminal （OLT）, the downstream unicast data are applied to one arm of a dual-parallel Mach-Zehnder modulator （DPMZM） to generate baseband unicast non-return-to-zero （NRZ） signal. A radio frequency （RF） control signal is applied to the other arm to present two un-modulated sidebands for multicast data modulation in a differential phase-shift keying （DPSK） format. The flexible and dynamic multicast services are realized by simply switching the RF control signal on or off. The proposed scheme is experimentally demonstrated with 1.25-Gb/s downstream unicast, multicast, and upstream data.
A hybrid wavelength division multiple access （WDMA）/optical code division multiplexing （OCDM） system is proposed, where the optical code is not the same as the address of every optical network unit （ONU）; rather, the code is a virtual fiber of hybrid passive optical network （PON）. To our knowledge, this is the first report analyzing a single encoder/decoder with a single corresponding optical code being exploited to encode/decode multiple wavelength signals simultaneously. This system enables OCDM to become transparent to ONU so that the existing wavelength division multiplexing （WDM） PON can be upgraded. Thus, redesigning the optical line terminal and ONU can be easily accomplished, and greatly decreasing the number of encoder/decoder becomes possible. In experiment, we only employ two encoder/decoder pairs to combine two WDM-PONs in one fiber. Simulation results confirm the feasibility of the proposed system.
In wavelength-division multiplexing （WDM） ethernet passive optical networks （EPONs）, to realize the statistical multiplexing of upstream wavelength resources, some optical tunable components are introduced in the optical network units. However, the switch latency （SL） of these tunable components constrains the performance of WDM-EPON. In this letter, we extend the mathematical model of the WDM interleaved polling with adaptive cycle time （IPACT） scheme by additionally considering the SL conditions. We also investigate the effect of channel SL on network performance. The simulation results show that the performance of WDM-IPACT-SL deteriorates as the SL increases.
