An V. Tran

Bandwidth-efficient PON system for broad-band access and local customer Internetworking

We present a new passive optical network (PON) architecture for broad-band access and local customer networking. It provides high bandwidth efficiency for delivering both PON and customer internetworking services. The architecture separates the local optical network from the PON system, thereby enhancing security, flexibility, and allowing the use of any media access control protocol. The local customer internetworking feature is demonstrated with insignificant penalty to the overall PON system performance.

Optical add-drop multiplexers with low crosstalk

We propose and demonstrate three new optical add-drop multiplexer (OADM) architectures with simple and compact configuration and excellent crosstalk performance. The OADMs use a single multiport optical circulator and either one or two narrow-band fiber Bragg gratings, depending on the crosstalk requirement.

EDFA transient control based on envelope detection for optical burst switched networks

We propose and demonstrate a simple technique to control rapid erbium-doped fiber amplifier (EDFA) transients in optical burst switched networks. We demonstrate a 6-dB transient reduction in a 10-Gb/s 80-km-long wavelength-division-multiplexing system with three EDFAs. We show through simulation that the technique can be used at the first EDFA in links of as many as ten EDFAs to control transients to within 2 dB.

Ethernet PON or WDM PON: A Comparison of Cost and Reliability

We report a comparison of cost and reliability of two optical broadband access technologies namely Ethernet passive optical network (EPON) and WDM PON (WPON), taking into account two protection schemes and two deployment scenarios. We derive simple network models and a figure of merit for network cost and reliability evaluation. We find that with a take rate ges 60%, WPON technology provides the lowest cost per subscriber per Mbit/s. Moreover, with full protection, the PON architectures achieve a low mean down time of 27 min/year, which is smaller than that of the copper-based access network.

10-Gb/s WDM-PON Based on Low-Bandwidth RSOA Using Partial Response Equalization

An extended reach 10-Gb/s wavelength division multiplexing passive optical network (WDM-PON) system based on a low-bandwidth reflective semiconductor optical amplifier (RSOA) is demonstrated using a novel partial response equalization (PRE) scheme. The proposed technique has good performance-complexity tradeoff compared to traditional equalization methods. The intrinsic feature of the signal directly modulated by RSOA and the impact of dispersion on the modulated signal are investigated. The result shows that the shape of the RF spectrum of the received signal can be predicted. Moreover, one target response can be applied for a wide range of transmission distances by properly setting the equalizer parameters. It is confirmed experimentally and via simulation that the proposed system can achieve good performance over 0 to 75 km fiber link using PRE with the same setup.

Statistical moments-based OSNR monitoring for coherent optical systems

We present a novel statistical moments-based method for optical signal-to-noise ratio (OSNR) monitoring in polarization-multiplexed (pol-mux) coherent optical systems. This technique only requires the knowledge of the envelope of the equalized signal before phase correction, which can be achieved by using any two arbitrary statistical moments, and it is suitable for both constant and non-constant modulus modulation formats. The proposed estimation method is experimentally demonstrated for 10-Gbaud pol-mux coherent systems using QPSK and 16-QAM. Additionally, numerical simulations are carried out to demonstrate 20-Gbaud systems using 16-QAM and 64-QAM. The results show that the OSNR can be estimated accurately over a wide range of values for QPSK, 16-QAM or 64-QAM systems up to 1920-km long and with up to 50-ps all-order polarization mode dispersion. By setting a proper reference value for calibration, the proposed algorithm also shows good tolerance when the received signal is not well compensated.

Data-Aided Chromatic Dispersion Estimation for Polarization Multiplexed Optical Systems

We propose a full transmission link chromatic dispersion (CD) estimation technique for polarization-multiplexed coherent optical single carrier system using data-aided channel estimation and least square quadratic fit. New training sequences based on Chu sequence and Golay complementary pair are designed and compared for estimation performance against the ideal full-level Chu sequence for both QPSK and 16-QAM systems. The proposed technique is demonstrated in a 40-Gb/s coherent polarization multiplexed optical system over 2080-km fiber transmission for QPSK format and 80-Gb/s system over 1800-km fiber for 16-QAM format to verify its accurate and robust estimation performance.

Implications of sleep mode on activation and ranging protocols in PONs

A sleep mode protocol for ONUs is proposed and its impact on re-activation procedures for GPON is examined. The new protocol does not disrupt in-service ONUs.

Cost-Effective Introduction and Energy-Efficient Operation of Long-Reach WDM/TDM PON Systems

Cost effectiveness and energy efficiency have recently become two practical issues during access networks construction and operation. In this paper, we extend our previous proposal of a remote channel combine/split module for long-reach wavelength division multiplexed and time division multiplexed passive optical network systems. Besides previously discussed benefits on investment cost and energy efficiency under take-up-rate-adaptive mode, this study shows that proposed systems help achieve higher energy saving by adopting traffic-adaptive power management. Simulation results show up to 35% power consumption saving at the time of minimum traffic demands. Moreover, in terms of energy consumption over periodic time, we find a typical 20% energy saving can be achieved compared to conventional systems in fully operated stage.

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Owing to its low transmitter complexity and low sensitivity to nonlinear impairments, phase noise, and frequency offset, the single carrier system with frequency domain equalization (SC-FDE) is of interest for high-bit-rate optical transmission. In this letter, we experimentally demonstrate a 8×40-Gb/s optical coherent polarization-multiplexed SC-FDE over 2080-km fiber transmission using novel training sequences. The sequences are designed based on Chu and Golay complementary sequences to have binary levels and are fully compatible with the commercial quadrature phase-shift keying (QPSK) systems. The use of these training sequences helps achieve accurate channel estimation and equalization in full-system demonstration.