Bidirectional Passive Optical Network Research Articles

Bidirectional Radio Frequency Up-Converted Orthogonal Frequency-Division Multiple Access Passive Optical Network With Novel Source-Free Optical Network Units Using Four-Wave Mixing in Semiconductor Optical Amplifier

We propose and demonstrate a bidirectional radio-frequency (RF) up-converted orthogonal frequency-division multiple access passive optical network (OFDMA-PON) system. Novel source-free optical network units (ONUs) are configured in the proposed OFDMA-PON system, which can support simultaneous and interference-free upstream transmission from multiple ONUs over a single wavelength in a single-fiber topology. The four-wave mixing effect in a semiconductor optical amplifier is utilized in the optical line terminal to enable its configuration. Experimental results successfully verify the feasibility of our proposed system.

Overlapped-Subcarrier Multiplexing for WDM Passive Optical Networks: Experimental Verification and Mathematical Analysis

An innovative overlapped-subcarrier multiplexing (O-SCM) technique is proposed for single-feeder wavelength-division multiplexed (WDM) passive optical networks (PONs). Allowing a certain amount of spectral overlap between the uplink and the downlink maximizes the spectrum usage of bandwidth-limited reflective semiconductor optical amplifier (RSOA)-based optical network units (ONUs), while reducing the effect of Rayleigh backscattering. In this paper, we report successful experimental demonstrations up to 2.5 Gb/s symmetrical bit rates over a ~20 km bidirectional PON, using a ~2 GHz bandwidth RSOA. Moreover, we mathematically address the major design issues and tradeoffs. Our simulation results show good agreement with the experiment.

Investigation of the Effects of Chirped RZ Signals in Reducing the Transmission Impairments in R-SOA-Based Bidirectional PONs

Distributed and concentrated reflections represent the two main limitations in reflective-semiconductor optical amplifier (R-SOA)-based passive optical networks (PONs). In this paper, we experimentally discuss how the use of chirped signals in centralized light seeding bidirectional PON can increase the resilience of the system against those two types of reflections. An experimental comparison of the performance of a highly chirped return to zero (RZ) modulation format and the nonreturn to zero is given. Error-free operation is achieved down to 10 dB of signal to crosstalk ratio in presence of distributed reflection, when the upstream signal is highly chirped RZ signal. The same chirped modulation leads to a tolerance of more than -25 dB network return loss due to concentrated reflections. Finally, we assess also the system feasibility of a R-SOA-based full-duplex PON where both the upstream and the downstream are modulated signals.

Performance Evaluation of Bidirectional Optical Amplifiers for Amplified Passive Optical Network Based on Broadband Light Source Seeded Optical Sources

We have evaluated the performances of bidirectional optical amplifiers which were suited for the cost-effective implementation of amplified bidirectional passive optical networks (PONs). First, we measured the maximum gains of two simple bidirectional optical amplifiers implemented without using any optical components for the suppression of reflected signals. From the results, the maximum gains of two simple bidirectional amplifiers with a broadband light source (BLS) seeded optical source were limited to be 27 dB due to the reflection-induced in-band crosstalk, when the reflectance coefficients were measured to be -33 dB in both directions. Then, we have also implemented a bidirectional optical amplifier with two band splitters for the amplified bidirectional PON where the two different wavelength bands were allocated to the downstream and upstream signals transmission. In our measurement, we confirmed that the maximum gain of bidirectional optical amplifier with two band splitters could be increased to more than 30 dB owing to the efficient suppression of in-band crosstalk.

Analysis of the influence of backscattered optical power over bidirectional PON links

Our aim is to describe the behavior of non-linear scattering effects that arise in standard single mode fiber (SMF), specifically scattering effects that propagate optical power in the reverse direction of the source signal such as Rayleigh Scattering (RS) and Brillouin Scattering (BS). For this purpose, the effects of backscattering phenomena over a bidirectional data transmission in a passive optical network (PON) scheme have been assessed. The impact of these high optical power components over reception at the optical line terminal (OLT) side has been determined when both links use the same wavelength. Bit Error Rate (BER) measurements have been performed with different transmission rates, using several techniques to mitigate the influence of backscattering over the received signal and considering cases with filtered and unfiltered BS.

Driving Requirements for Wavelength Shifting in Colorless ONU With Dual-Arm Modulator

Dual-arm modulator configurations to perform wavelength shifting at the optical network units (ONUs) for the mitigation of Rayleigh backscattering impairment in bidirectional centralized-light passive optical networks (PONs) are proposed, with different solutions compared. A 7 dB of sensitivity improvement due to the reduction in the Rayleigh scattering crosstalk between up- and down-stream signals is achieved with a suboptimal solution based on a conventional Mach-Zenhder modulator.

High speed and secure optical CDMA-based passive optical networks

One bi-directional passive optical network (PON) based on optical code-division multiple access with interference elimination is proposed. By combining with wavelength division multiplexing (WDM) technique, the proposed scheme alleviates the noise arising during photo-detecting process in the PON. Therefore, the bit error rate performance is improved, which is demonstrated by the results of performance analysis. In addition, simple and low cost encoding/decoding structures with small sizes in the optical line terminal are proposed, and they can cooperate with the dynamic codeword assignment scheme to provide a more secure signal transmission in the PONs.

Bidirectional dense wavelength-division multiplexing passive optical network based on injection-locked vertical-cavity surface-emitting lasers and a data comparator

A bidirectional dense wavelength-division multiplexing (DWDM) passive optical network (PON) based on injection-locked vertical-cavity surface-emitting lasers and a data comparator is proposed and demonstrated. Improved performance with respect to bit error rate and eye diagram was observed. Bidirectional transmission in DWDM-PON architecture is a very attractive option; the capacity of the optical network can be expanded relatively easily in that way.

Bidirectional WDM passive optical network for simultaneous transmission of data and digital broadcast video service

We have demonstrated an easily upgradable bidirectional passive optical network for the simultaneous transmission of wavelength-division-multiplexing channels and digital broadcast video signals. The proposed network could transmit 15 2.5-Gb/s downstream channels, 15 155-Mb/s upstream channels, and one broadcast signal consisting of more than 70 digital video channels.

Remotely Pumped Hybrid Amplifiers for Extended Bidirectional Passive Optical Networks

In this contribution, we optimize design parameters of hybrid optical amplifiers utilizing distributed Raman amplification in transmission fiber and gain of discrete, remotely pumped erbium-doped fiber amplifier (EDFA) for wideband, bidirectional operation in metropolitan area networks (MAN). The design is based on an application of a numerical model, which takes into account pump-to-pump and signal-to-signal interactions and generation of amplified spontaneous emission in the Raman amplifier and solves the standard rate-propagation equations in an erbium-doped fiber (EDF). We predict 12 dB gain across 72 nm of optical bandwidth with gain ripple better than 10%. The recently proposed serial topology of EDFA is considered; this enables the wideband, bidirectional operation of a hybrid amplifier with only two pump laser diodes emitting in the 1430 and 1480 nm bands.

Remotely Pumped Hybrid Amplifiers for Extended Bidirectional Passive Optical Networks

Remotely Pumped Hybrid Amplifiers for Extended Bidirectional Passive Optical Networks

Spectrum-sliced bidirectional passive optical network for simultaneous transmission of WDM and digital broadcast video signals

A bidirectional WDM passive optical network based on the spectrum-slicing technique for both broadband switched services and digital broadcast video services is demonstrated. This network is capable of providing a 155 Mbit/s baseband signal and 30 digital video signals to each subscriber. The upstream channels also operate at 155 Mbit/s.

Bi-directional passive optical network for CDMA personal communication service

A bi-directional passive optical network for CDMA personal communication service is proposed and demonstrated. The relaxed dynamic range requirements of CDMA signals allows the use of a double-star architecture. This network could be implemented cost-effectively by using one 1.3 µm Fabry-Perot laser for the downlink and 1.3 µm LEDs for the uplink.