Wavelength Division Multiplexed Passive Optical Network System Research Articles

WDM PONs based on colorless technology

Wavelength Division Multiplexing (WDM) Passive Optical Network (PON) is foreseen to be part of the Next Generation Passive Optical Networks. Business and mobile fronthaul networks already express the need to develop WDM PONs in the access segment. Fixed wavelength transceivers based on Coarse WDM are already available to respond to today’s market needs but Dense WDM technologies will be needed and colorless technologies are essential to provide simple and cost-effective WDM PON systems. We propose in this paper to demonstrate the capabilities of a DWDM PON system prototype based on self-seeded RSOAs and designed to transmit CPRI over 60km of fiber at 2.5Gbit/s.

TWC and AWG based optical switching structure for OVPN in WDM-PON

With the rapid development of optical elements with large capacity and high speed, the network architecture is of great importance in determing the performance of wavelength division multiplexing passive optical network (WDM-PON). This paper proposes a switching structure based on the tunable wavelength converter (TWC) and the arrayed-waveguide grating (AWG) for WDM-PON, in order to provide the function of opitcal virtual private network (OVPN). Using the tunable wavelength converter technology, this switch structure is designed and works between the optical line terminal (OLT) and optical network units (ONUs) in the WDM-PON system. Moreover, the wavelength assignment of upstream/downstream can be realized and direct communication between ONUs is also allowed by privite wavelength channel. Simulation results show that the proposed TWC and AWG based switching structure is able to achieve OVPN function and to gain better performances in terms of bite error rate (BER) and time delay.

Experimental Study of Type B Protection for a TWDM-PON System [Invited

A passive optical network (PON) protection scheme is needed to ensure the system reliability required for business use, as PON is based on sharing a single fiber via an optical distribution network. Protection switching time is an important factor for business applications because it defines the service outage duration when a failure occurs. In this paper, we propose a PON protection scheme that enables the service outage duration to be reduced. We demonstrate Type B protection for a time and wavelength division multiplexed PON system and discuss the service outage duration.

Performance Analysis of WDM-PON System Based on Optimized Remotely Pumped Erbium-Doped Fiber Amplifier (EDFA) Parameter

AbstractIn this paper, the performance of wavelength division multiplexing-passive optical network (WDM-PON) system using the erbium-doped fiber amplifier (EDFA) is optimized and evaluated. The optimization is analyzed by finding the EDFA length range at which the output power produced are the highest and the pump power range at which the gain flatness produced are within the effective range (0.3 dB). After the optimization process, the optimized EDFA system produces the gain of 26.6±0.292 dB, noise figure of 3.82 dB and output power of 7 dBm and the system is then implemented into WDM system. The performance of WDM system is compared against the system without EDFA in terms of bit error rate (BER). Results obtained prove that the proposed system with the EDFA consistently performs better than the conventional system.

Performance investigation of optical multicast overlay system using orthogonal modulation format

We proposed a bandwidth efficient wavelength division multiplexed-passive optical network (WDM-PON) to simultaneously transmit 60Gb/s unicast and 10Gb/s multicast services with 10Gb/s upstream. The differential phase shift keying (DPSK) multicast signal is superimposed onto multiplexed non-return to zero/polarization shift keying (NRZ/PolSK) orthogonal modulated data signals. Upstream amplitude shift keying (ASK) signals formed without use of any additional light source and superimposed onto received unicast NRZ/PolSK signal before being transmitted back to optical line terminal (OLT). We also investigated the proposed WDM-PON system for variable optical input power, transmission distance of single mode fiber in multicast enable and disable mode. The measured Quality factor for all unicast and multicast signal is in acceptable range (>6). The original contribution of this paper is to propose a bandwidth efficient WDM-PON system that could be projected even in high speed scenario at reduced channel spacing and expected to be more technical viable due to use of optical orthogonal modulation formats.

First Demonstration of a WDM-PON System Using Full C-band Tunable SFP+ Transceiver Modules [Invited

In this paper, a wavelength-division-multiplexing passive optical network (WDM-PON) system using small form-factor pluggable plus (SFP+) packaged full C-band tunable transceivers is demonstrated for the first time to our knowledge. Within the transceivers, a novel digital-supermode distributed Bragg reflector (DS-DBR) laser with a monolithically integrated Mach–Zehnder modulator is employed as the transmitter. A generic current control algorithm is used to drive the DS-DBR laser, which employs a laser current training sequence ensuring successful operation without the need for individual laser characterization. A pilot-tone-based feedback control loop is implemented using embedded hardware, which is able to lock the output wavelengths from three identical optical network units with less than ±3  GHz deviation from their assigned channels. Error-free transmission is achieved at a 10 GbE data rate. With the feedback control loop running continuously, the system shows a sensitivity of −23  dBm for a bit error rate of 10−12.

Transmission of 4× 40/10 Gbps in a WDM-PON using NRZ-DQPSK/ASK modulation

In this paper we demonstrate the feasibility to deploy a wavelength division multiplexing passive optical network (WDM-PON) of a 30km standard single-mode fiber (SSMF-28) carrying 160Gbps data in downstream and 40Gbps through the uplink. The developed method is based on the comparison between two WDM-PON systems of 4 channels with the same characteristics, using two different formats of modulation in OLTs. The first system uses the NRZ-ASK in the downlink direction, while the second uses the NRZ-DQPSK.

Long Reach 10-Gbps WDM-PON Based on Carrier Distribution and Coherent Detection for Upstream Transmission

The wavelength division multiplexing passive optical network (WDM-PON) incorporated with colorless optical network units (ONUs) and centralized light source is the most promising approach for next generation PON. A cost-effective architecture utilizing coherent detection for upstream (US) signal is proposed to enlarge the reach of such WDM-PON systems. Simulation results show that a symmetric 10-Gbps WDM-PON with 80km error-free transmission is realized without using any optical amplifiers.

Modeling and Simulation of Chaos-Based Security-Enhanced WDM-PON

A physical security-enhanced wavelength division multiplexed passive optical network (WDM-PON) based on chaos synchronization between twin laser pairs is introduced. Differing from the conventional WDM-PON systems, the downstream and upstream data are physically encrypted by chaotic carriers, and the decryption processes are performed based on WDM chaos synchronization. We numerically demonstrate that with sufficient wavelength spacing, a high quality chaos synchronization between the chaotic carriers with identical wavelength can be maintained, which enables the proposed WDM-PON to afford multichannel chaotic communications at high bit rates in both the downstream and upstream directions; in addition, the security of the physical layer can be greatly enhanced. The proposed scheme shows a potential way for implementing physically-secure PONs.

Wavelength self-initialization technique using allocated light paths of WDM-PON

A new wavelength initialization technique for WDM-PON (wavelength division multiplexed-passive optical network) system is proposed, where it uses allocated light path over optical link. Compared with other techniques, it is expected that the smallest size and the lowest cost for implementing this will be achieved in the real network. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:753–755, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27426

Single fiber colorless symmetric WDM-PON architecture using time interleaved remodulation technique for mitigating Rayleigh backscattering resilience

A time interleaved differential phase shift keying (DPSK) remodulation technique is proposed to mitigate the effect of Rayleigh backscattering (RBS)-induced noise in a single fiber colorless wavelength-division-multiplexing passive optical network (WDM-PON). In order to achieve a cost effective optical network unit (ONU) solution without dedicated laser sources for upstream signals to provide optimum symmetric capacity in a colorless WDM-PON, remodulation becomes the core attraction. Also as the performance of colorless WDM-PON systems suffers from the transmission impairments due to RBS, it is mitigated by using this remodulation scheme. Simulation results show that downstream and upstream signals achieve the error-free performance at 10 Gbit/s with negligible penalty, and enhance the tolerance to RBS-induced noise over a 25 km single-mode fiber.

An AWG-based 10 Gbit/s colorless WDM-PON system using a chirp-managed directly modulated laser

We propose an arrayed waveguide grating (AWG)-based 10 Gbit/s per channel full duplex wavelength division multiplexing passive optical network (WDM-PON). A chirp managed directly modulated laser with return-to-zero (RZ) differential phase shift keying (DPSK) modulation technique is utilized for downlink (DL) direction, and then the downlink signal is re-modulated for the uplink (UL) direction using intensity modulation technique with the data rate of 10 Gbit/s per channel. A successful WDM-PON transmission operation with the data rate of 10 Gbit/s per channel over a distance of 25 km without any optical amplification or dispersion compensation is demonstrated with low power penalty.

Demonstration of 40-Gb/s WDM-PON System Using SOA-REAM and Equalization

The wavelength-division-multiplexed passive optical network (WDM-PON) has been widely considered as the ultimate solution for future bandwidth-hungry access networks. However, in WDM-PON, the necessity of colorless operation and low cost constrains the choice of upstream transmitter and thus limits the achievable data rate. The integrated semiconductor optical amplifier-reflective electro-absorption modulator (SOA-REAM) is a promising candidate for uplink transmitter, because of its wide modulation bandwidth and low chirp. In this letter, a novel equalization technique based on noise predictive maximum likelihood (NPML) and partial response (PR) signaling is proposed to enable SOA-REAM-based 40-Gb/s WDM-PON. We experimentally demonstrate a 40-Gb/s error-free transmission over 20-km, using a 20-GHz SOA-REAM. Moreover, the performance of the proposed PR-NPML equalizer is compared with that of other common equalizers in both the transmission and the reflection studies.

Improving performance of MLSE in RSOA-based WDM-PON by partial response signaling

High data-rate upstream transmission in wavelength division multiplexed passive optical network (WDM-PON) based on reflective semiconductor optical amplifier (RSOA) is limited by severe inter-symbol interference (ISI), owing to low-bandwidth transmitter and fiber dispersion. To overcome the limitations in RSOA-based WDM-PON, we propose a novel receiver based on partial response maximum likelihood (PRML) equalization which combines the use of partial response (PR) signaling with maximum likelihood sequence estimation (MLSE). MLSE has been long considered as the optimal reception technique to overcome various types of impairment in optical transmission such as dispersions. It is demonstrated in this paper that PRML surpasses standard MLSE in ISI and reflection suppression with reduced complexity for RSOA-based WDM-PON system. 150 km unidirectional distance is demonstrated for 10 Gb/s uplink, while bidirectional uplinks up to 50 km and 20 km are achieved for data rate of 10 Gb/s and 20 Gb/s respectively, in WDM-PON using PRML. Furthermore, the impacts of discrete reflections on various equalization techniques are investigated, where PRML also shows superiority over MLSE.

Tunable External Cavity Laser by Hybrid Integration of a Superluminescent Diode and a Polymer Bragg Reflector

We report a tunable external cavity laser (T-ECL) using a superluminescent diode (SLD) and a polymer Bragg reflector with 0.8-nm mode spacing 25 channels operating in the direct modulation of 2.5 Gb/s for a low-cost source of a wavelength division multiplexed passive optical network (WDM-PON) system. The maximum output power is 12.2 mW and the slope efficiency of the T-ECL is about 0.12–0.17 mW/mA in the tuning range of 20 nm at the SLD current of 50 mA and at the temperature of 25 °C. The T-ECL successfully operated in the direct modulation for 2.5-Gb/s transmission through 20-km standard single-mode fiber. The power penalty of the T-ECL is less than 0.8 dB for 25 channels after the 20-km transmission. The power penalty variation is less than 1.5 dB in the wavelength-tuning range of 20 nm. The performance of the T-ECL satisfies the requirements of the WDM-PON system.

Simulation and Comparison of Advanced Modulation Formats for Wavelength Reuse in High-SpeedWDM-PON System

In recent years, the innovation in devices and schemes of physical layer plays an important role in promoting the development of WDM-PON (Wavelength Division MultiplexingPassive Optical Network).Among the key technologies adopted in the WDM-PON system, advanced modulation formats at downstream and remodulations at upstream attract the most attention. DPSK (Differential Phase Shift Keying Modulation), FSK(Frequency-Shift Keying), IRZ(Inverted Return-to-Zero) and Manchester are four of the most common formats and each of them was studied before, but, however, nobody compared and analyzed them together.So, we will do the job by numeralsimulation in this paper. During our simulation, the 40-Gbit/s FSK is generated through the demodulation of two DPSK signals and 40-Gbit/s Manchester signal bases of employing a delay interferometer (DI) and an optical delay line as format conversion device to convert RZ-DPSK(Return to Zero-Differential Phase Shift Keying Modulation) coding to Manchester coding, both of the two format generation schemes are novel.Meanwhile,this paper emphasizes the input optical power and dispersion tolerance, which both related to the sensitivity of the system. Analyze the sensitivity with DPSK, FSK, IRZ and Manchester, and then compare the four advanced modulation formats.

Analysis the Speciality of Modulation Format in WDM-PON System

In the wavelength division multiplexing passive optical network (WDM-PON) system, the modulation format was important. While three different modulation formats including not-return-to-zero (NRZ), return-to-zero (RZ), carrier-suppressed return-to-zero (CS-RZ) and the optical differential quadrature reference phase shift keying (DQPSK) modulation format of each code are introduced in the article. A method of their modulated signal generation with computer is described, and a comparison of their spectra and waveforms is made. The 40 Gbps signal transmitted in 200 km G.652 fiber by way of single channel with erbium-dope-fiber-amplifier (EDFA) is simulated for these three formats. It is showed that the ability of anti-dispersion and anti-PMD (Polarization Mode Dispersion) is better in the CS-RZ-DQPSK modulation format, and this format has the smallest eye-opening penalty with a wider range of power into the optical fiber.

A Novel Reliable WDM-PON System

In this paper, a reliable Wavelength-Division-Multiplexing Passive Optical Network (WDM-PON) system is proposed. It can provide the protection against both the feeder fiber failure and the distribution fiber failure. When the fiber failure occurs, the corresponding switches in the OLT and in the ONU can switch to the protection link without affecting the users in normal status. That is to say, the protection for one ONU is independent of the other ONUs.

Proposal of Spectrum-Interleaved Duplex WDM-PON Using Spectrum-Sliced Broadband Incoherent Light with Reflection Remover

A Wavelength division multiplexing passive optical network (WDM-PON) system that uses spectrum-sliced broadband incoherent light is attractive because it avoids the cost of operating/administering wavelengths in optical network units (ONU) at customer premises. However, it is difficult to enhance the spectrum efficiency to ensure a sufficient signal to noise ratio because it would demand broad channel width. To overcome this problem, we proposed a spectrum-interleaved duplex technique. It enables upstream and downstream communications to share one channel by using a cyclic filter. This sharing of one channel eliminates the need for a guard interval between signal lights duplexed in the channel. One residual issue regarding single band transmission is its robustness to reflection in the transmission medium. To increase the reflection robustness of the spectrum-interleaved duplex scheme, we propose a reflection remover based on an optical code division multiplexing technique. We also evaluate the extent to which capacity of the spectrum efficiency of the spectrum-interleaved duplex WDM-PON system that uses spectrum-sliced broadband incoherent light can be increased.

A Weak-Resonant-Cavity Fabry–Perot Laser Diode With Injection-Locking Mode Number-Dependent Transmission and Noise Performances

Quasi-color-free weak Fabry-Perot cavity laser diode with long cavity length is one alternative solution of the wavelength-division-multiplexed passive optical network (WDM-PON) transmitter with comparable broadband gain spectrum and greatly reduced noise figure as compared to typical reflective semiconductor optical amplifiers. In this paper, the amplified spontaneous emission injection-locked weak-resonant-cavity Fabry-Perot laser diode (WRC-FPLD) with 1% front-facet reflectivity directly modulated at 1.25 Gbit/s with detuning injection-locked mode for quasi-color-free transmission in WDM-PON system with channel spacing of 200 GHz is demonstrated. With bias current changing from 0.9 Ith to 1.4 Ith, the improvement on receiving power sensitivity for the WRC-FPLD-based WDM-PON transmitter is up to 9 dB at bit error rate (BER) of 10-9. Increasing the injection-locked mode number from 2 to 3 within temperature variation of 6°C effectively promotes the BER from 10-8 to 10-10 at receiving power of -27 dBm associated with a decreasing power penalty of -3.2 dB. The WRC-FPLD with more injection-locked modes within one channel exhibits higher extinction ratio at higher operating temperature within one injection-locked-mode-number changing period. This elucidates well the cycling evolution on the BER performance of the WRC-FPLD as a function of operating temperature.