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Abstract: We propose and demonstrate a 10Gb/s wavelength division multiplexed passive optical network (WDM-PON) where subcarriers are employed to transmit the downstream data and optical carriers of the downlink subcarrier modulated (SCM) lights are reused to injection lock Fabry-Perot laser diodes (FP-LDs) for uplink transmission. Experiment results show that a very good BER performance can be achieved for both uplink and downlink at 10Gb/s. The impact of optical carrier to subcarrier ratio and wavelength mismatching is also investigated. [Copyright &y& Elsevier]

Abstract: In this paper, we analyze the survivability of wavelength division multiplexed (WDM) passive optical network (PON). We propose and experimentally demonstrate a novel survivable WDM-PON architecture with self-protection and in-service fault localization capabilities. Two WDM-PONs are combined together and multiple sub-ring architecture is formed. Protection switching is achieved automatically at optical network units (ONUs) when failure occurs. Fiber loss, fiber fault localization and automatic protection switching in each ONU are real-time monitored in central office (CO) without interrupting customer service. No signaling for failure notice or protection switching is required for either CO or ONUs. Extra fibers required for protection are minimized compared with previous protection schemes. The self-protection and in-service fault localization capabilities of the proposed WDM-PON architecture are experimentally verified. [Copyright &y& Elsevier]

Abstract: In this paper, we present an orthogonal labelling scheme using inverted return-to-zero (IRZ) as payload and differential-phase-shift-keying (DPSK) as label. Transmission performances of orthogonal labelling with 40Gb/s IRZ payload and 10Gb/s label are evaluated. Simulation results show that orthogonal labelling using IRZ as payload exhibits a much larger extinction ratio margin than that of using return-to-zero (RZ) as payload. The asynchronous effect between payload and label on the transmission performances of orthogonal labelling using IRZ and RZ as payload is evaluated. Simulation results show that the degradation of asynchronous orthogonal labelling using IRZ as payload is relatively worse than that of using RZ as payload. The impact of optical filter bandwidth before receivers is also investigated. Results show that the receiver sensitivities of label for IRZ/DPSK and payloads for both IRZ/DPSK and RZ/DPSK are degraded with the reduction of the filter bandwidth, while the label of RZ/DPSK exhibits an opposite trend. [Copyright &y& Elsevier]

Abstract: This paper presents the detailed principle on the generation and detection of optical minimum shift keying (MSK) format for high-speed and high spectral efficiency WDM systems. 10.7Gb/s optical MSK data is successfully generated by experiment using the proposed scheme. The results show that optical MSK signal exhibits very compact optical spectrum, which is promising for high spectral efficiency WDM applications. Simulation results on dispersion and nonlinear tolerance comparison confirm that MSK signal has better dispersion tolerance and nonlinear tolerance compared with 50% duty cycle return-to-zero differential phase shift keying (RZ-DPSK) and 50% duty cycle RZ on-off-keying (RZ-OOK) formats. [Copyright &y& Elsevier]

Abstract: We propose, a novel upstream transmission scheme for high speed wavelength division multiplexed passive optical networks. Upstream transmission at bit rate of 2.5Gb/s was demonstrated using a Fabry–Perot (FP) laser diode (LD) externally injected by a spectrum-sliced polarization-insensitive supercontinuum pulse source, located at central office. The impact of Rayleigh backscattering on transmission performance is also investigated. The proposed scheme is expected to be cost-effective since low-cost FP LDs are used for light sources. [Copyright &y& Elsevier]

This paper evaluates and compares a range of optical pulse shapes for long-haul high-capacity dense wavelength division-multiplexed (DWDM) transmission links with return-to-zero (RZ) modulation format, in terms of their transmission performance and characteristics. Performance is compared at both 10 and 40 Gbit/s, using several different types of transmission fibre. Results show that different pulse shapes exhibit different optimal duty cycle and launch power level into the transmission fibre. In addition, the optimum values and the maximum achievable Q values also depend on transmission fibre type used due to the interplay between optical amplifier noise, fibre dispersion, nonlinear effects, and linear crosstalk from demultiplexers. For both 10 and 40 Gbit/s transmission, super Gaussian waveform gives the best transmission performance and largest optimal duty cycle, hyperbolic secant exhibits the worst Q value and smallest optimal duty cycle, and Gaussian is intermediate between for all the transmission fibre types considered. [Copyright &y& Elsevier]

Abstract: A fiber-based wavelength-division-multiplexing (WDM) network utilizing polarization multiplexing (PolMUX) is proposed to simultaneously provide broadband wireless and wired services. In such a dual-service access network, the wireless and wired services are separately delivered in two orthogonal states of polarization with well independence in a single WDM channel. The impact of several polarization-dependent interferences becomes insignificant due to the relatively short transmission distance in access networks. The feasibility of PolMUX is experimentally demonstrated with a power penalty at BER=10–9 of about 0.5dB and 1dB for 2.5Gb/s wired and wireless downstream services, respectively. The proposed system is compatible with the current reported techniques in either WDM passive optical networks (WDM-PON) or radio-over-fiber (ROF) systems. [Copyright &y& Elsevier]

Abstract: Based on dual-order stimulated Raman scattering (SRS) of a single 1395nm Raman fiber laser in 75km single mode fiber and its corresponding dispersion compensation module, a hybrid Raman/Erbium doped fiber amplifier (EDFA) for long wavelength band (L-band) amplification is realized by inserting a segment of EDF within the span. By comparing the performance of gain and noise in four hybrid amplifiers with different span configurations, we find that the distribution of the secondary L-band amplification obtained from the EDF along the link has a great influence on the performance of the hybrid amplifier. Both gain and noise performance of hybrid amplifier can be improved significantly by optimizing the location of the EDF. Moreover, we can extend the flat gain bandwidth from L-band to central wavelength band (C-band) plus L-band by recycling the residual first-order SRS to pump a segment of EDF with proper length. [Copyright &y& Elsevier]

Abstract: We have systematically studied the dispersion properties of a 40 channel×10 Gbit/s wavelength division multiplexed (WDM) transmission link using standard single mode fibre with all EDFA amplification, over 30×100 km spans. The dispersion map of the link was investigated by adding fibre sections with positive or negative dispersion at the transmitter, within each amplifier span, and at the receiver. Optimum combinations of these dispersive fibre lengths were found to significantly enhance the overall transmission performance. The dispersion slope mismatch between the transmission fibre and compensation fibre was investigated using the optimal dispersion map. The tolerable range of slope mismatches was found using a post-compensation method for individual channel compensation and overall channel compensation. [Copyright &y& Elsevier]

Abstract: We experimentally demonstrate an all-optical 10Gb/s format conversion from non-return-to-zero (NRZ) on-off-keying (OOK) to return-to-zero (RZ)-OOK with tunable duty cycle in the whole C-band using nonlinear polarization rotation (NPR) arising in an semiconductor optical amplifier (SOA). The experimental results show that, by tuning the polarizer at the SOA output, an RZ signal with tunable duty cycle from 33% to 66% could be obtained with an extinction ratio(ER) over 10dB. In addition, we show that the NRZ-to-RZ conversion with duty cycle of 33–66% can be obtained with less than 1dB power penalty at the bit error ratio (BER) of 10−9. The device can facilitate the cross-connection between optical transmission networks employing different modulation formats. [Copyright &y& Elsevier]