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We describe the mathematical model and present simulation results for the optimization of a hybrid Raman/optical parametric amplifier (HROPA), exhibiting a bandwidth of 170 nm and low ripple that covers the top half of the wavelength plan (e.g., 1441 to 1611 nm) of next generation coarse wavelength division multiplexed passive optical network systems. We show that a critical parameter in the proper amplifier parameter optimization is the inclusion of the fourth-order dispersion coefficient (β(4)). Omission of β(4) can lead to over-estimation or underestimation of the gain bandwidth, and hence its inclusion in the analysis of the HROPA is necessary.

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Passive optical network (PON) architectures have been proposed as a back haul for wireless networks, where the optical network units (ONUs) can now be interconnected with the antenna base stations. We focus on a ring PON approach with its inherent benefits and use simulation to analyze the effects of linear crosstalk in an un-amplified basic TDM optical ring. Our approach is based on simulation of the entire network using a combination of wavelength-domain and time-domain techniques. Typically PON networks are based on CWDM to maintain the cost of components low and in such case it is logical that any crosstalk will be negligible. However, the subpar performance of such components motivated our study into the crosstalk impact. We show that the tap ratio optimization which increases the number ONUs that can be served in the ring can also exacerbate the effects of linear interchannel crosstalk at the ONU's downstream signal receivers. The interchannel crosstalk originates from the upstream/LAN transmission and is due to nonideal WDM couplers/splitters and optical switches that are needed for wavelength multiplexing/demultiplexing and protection against node and link failures, respectively.

There is increased interest in ring-based passive optical network (PON) architectures due to their local area network (LAN) capability among end users and inherent protection and restoration schemes. The ring architecture includes optical filters and switches with non-ideal channel isolation, leading to the generation of linear crosstalk, which can significantly degrade the system performance if it is not sufficiently suppressed. We use simulation to analyze the effects of linear crosstalk in an un-amplified TDM optical ring and show how we can improve the tolerance of the crosstalk in our architecture that employs optimized tap split ratios as a means of increasing the number of ONUs served. Our approach is based on simulation of the entire network using a combination of wavelength-domain and time-domain techniques. Typically, PON networks use two or three wavelengths that are separated by more than 50 nm to maintain the cost of components low and as such, it is logical that any crosstalk will be negligible. However, the subpar performance of such components motivated our study into the impact of crosstalk. We show that the tap ratio optimization which increases the number ONUs that can be served in the ring can also exacerbate the effects of linear interchannel crosstalk at the ONU's downstream signal receivers. We also show that surplus power at the last ONU can be utilized to counter this degraded crosstalk performance by careful tap ratio selection, thereby improving the overall tolerance to linear crosstalk in the system.

We describe a hybrid Raman-optical parametric amplifier (HROPA) operating at the O-and E-bands and designed for coarse wavelength division multiplexed (CWDM) passive optical networks (PONs). We present the mathematical model and simulation results for the optimization of this HROPA design. Our analysis shows that separating the two amplification processes allows for optimization of each one separately, e.g., proper selection of pump optical powers and wavelengths to achieve maximum gain bandwidth and low gain ripple. Furthermore, we show that the proper design of optical filters incorporated in the HROPA architecture can suppress idlers generated during the OPA process, as well as other crosstalk that leaks through the passive optical components. The design approach enables error free performance for all nine wavelengths within the low half of the CWDM band, assigned to upstream traffic in a CWDM PON architecture, for all possible transmitter wavelength misalignments (6 nm) from the center wavelength of the channel band. We show that the HROPA can achieve error-free performance with a 170-nm gain bandwidth (e.g., 1264 nm-1436 nm), a gain of >20 dB and a gain ripple of <4 dB. OPEN ACCESSPhotonics 2014, 1 474

Passive optical network (PON) is the leading technology being used for delivering last-mile connectivity without any active components in the distribution network. In this paper, we focus on an un-amplified hybrid tree-ring PON architecture that carries the benefits of both the tree and the ring architectures. Through simulation, we demonstrate the optical performance of the system and focus on the physical layer performance impact of interchannel and intrachannel crosstalk due to non-ideal WDM multiplexers/demultiplexers and optical switches in the system.