P.J. Urban

Densely integrated microring resonator based photonic devices for use in access networks

Two reconfigurable optical add-drop multiplexers, operating in the second or third telecom window, as well as a 1x4x4 reconfigurable lambda-router operating in the second telecom window, are demonstrated. The devices have a footprint less than 2 mm(2) and are based on thermally tunable vertically coupled microring resonators fabricated in Si(3)N(4)/SiO(2).

Interferometric Crosstalk Reduction in an RSOA-Based WDM Passive Optical Network

Reflection and Rayleigh backscattering-induced interferometric crosstalk in a link employing a reflective semiconductor optical amplifier (RSOA) may cause significant power penalty and, thus, limit the performance of the system. In this paper, we investigate interferometric crosstalk suppression in a centralized light generation wavelength division multiplexing-passive optical network (WDM-PON) by single-tone phase modulation either by utilizing the nonlinear behavior of the RSOA at the optical network unit (ONU) or by applying an external phase modulator at the source side. 6- and 7-dB reduction in power penalty for reflection-induced crosstalk is achieved, respectively. For Rayleigh backscattering-induced crosstalk power penalty is improved with 3 and 4.5 dB, respectively. The results show that an RSOA is very sensitive to reflections and backscattering and the tolerance to these impairments can be significantly improved by appropriate phase modulation. A comparison with advantages and disadvantages of both methods together with final recommendation is also given in the paper.

High-Bit-Rate Dynamically Reconfigurable WDM–TDM Access Network

The intensification of traffic in the access network requires the development of novel architectural solutions for a reconfigurable network topology and components based on optical technologies. We present a hybrid ring-shaped wavelength division multiplexing (WDM)-time division multiplexing (TDM) passive optical network (PON) that is capable of providing bandwidth on demand at high bit rates in a transparent and dynamic manner. Our cost-efficient and scalable network architecture is based on integratable components such as a wavelength-agile optical networking unit and a microring-resonator-based remote node. An appropriately modified control layer is introduced to manage the network. We also discuss the implementation of optical codes instead of time slots to take the step toward optical code division multiplexing (OCDM) WDM PONs that relieve the network of strict time scheduling of traffic and ranging. Therefore, an additional reduction of complexity in network management, improvement of network scalability, and a guarantee of fully symmetric traffic are foreseen for every user. Finally, we show a scenario for smooth migration from existing PON solutions to our WDM-TDM PON architecture.

Mitigation of Reflection-induced Crosstalk in a WDM Access Network

Reduction of reflection-induced crosstalk in a link employing Reflective Semiconductor Optical Amplifier achieved by applying Bias Dithering at RSOA and Phase Modulation at the source gives 6dB and 7dB improvement in power penalty, respectively.

1.25-Gb/s Transmission Over an Access Network Link With Tunable OADM and a Reflective SOA

The emerging broadband services and the avalanche-like growth of the broadband subscribers result in the intensification of data traffic in access networks. This drives the development of last-mile technologies to support multiservice provision on high bit-rate-capable reconfigurable networks. In this letter, we present the first transmission experiments carried out on the testbed of a hybrid wavelength-division-multiplexing/time- division-multiplexing access network based on cost-efficient elements like an integrated optical add-drop multiplexer and a reflective semiconductor optical amplifier. We successfully transmit two 1.25-Gb/s wavelength channels over 26-km standard single-mode fiber carrying data to and from the user.

1.25 - 10 Gbit/s Reconfigurable Access Network Architecture

In this paper we propose a novel reconfigurable access network architecture which enables the bidirectional transmission of 1.25 - 2.5 Gbit/s. Optical network units (ONUs) are equipped with a reflective semiconductor optical amplifier (RSOA) and remote nodes (RNs) are based on microring resonators - both contribute to network transparency and flexibility. We also propose ONU upgrade to serve 10 Gbit/s per end-user. Next to the theoretical description and transmission simulations some principle measurement results are presented which show the feasibility of the concept.

All-Optical Label Extractor/Eraser for In-Band Labels and 160-Gb/s Payload Based on Microring Resonators

Photonic integration of an all-optical packet switch (AOPS) is a crucial issue since it leads to a great reduction of volume, power consumption, and costs. Recently, a 1 times 4 AOPS was successfully demonstrated by using an all-optical label extractor/eraser. The label extractor/eraser was implemented by means of fiber Bragg gratings and optical circulators that prevent the photonic integration of the AOPS. Here, we demonstrate a passive and asynchronous photonic integrated all-optical label extractor/eraser by using narrowband silicon-nitride add-drop ring-resonators. By exploiting the narrow bandwidth of the drop port and pass-through port error-free simultaneous separation/erasing of the in-band labels from the 160-Gb/s packet payload was demonstrated without noticeable pulse-shape distortions.

Reconfigurable WDM/TDM Access Network Providing 10-Gb/s/

Due to the emerging bandwidth-hungry applications (e.g., high-quality video content), the traffic load may significantly vary in time across the access network. Therefore, the network operator should be capable of distributing the available bandwidth in a flexible manner in order to provide the end-user with an uninterrupted service. In this letter, we present the experimental results carried out on the testbed of a hybrid wavelength-division-multiplexing/time-division-multiplexing access network based on cost-efficient elements like an integrated optical add-drop multiplexer and a reflective electroabsorption modulator combined with a semiconductor optical amplifier which provides bandwidth on-demand. We successfully transmit simultaneous upstream and downstream traffic at 10 Gb/s/lambda (nonreturn-to-zero) over 27-km standard single-mode fiber in various configurations of four wavelengths.

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In this paper we describe experiments performed on a testbed of a novel dynamically reconfigurable access network capable of providing bandwidth on-demand to the end-users. Multiwavelength bidirectional transmission of 10 Gb/s channels in different bandwidth allocation schemes is achieved while sustaining substantial power budget to cover the attenuation of over 25 km standard SMF and related power penalties e.g. due to Rayleigh backscattering.

Over 27-km SSMF With Colorless ONU

In this paper, we demonstrate symmetrical bidirectional transmission of 1.25 Gbit/s wavelength channels in an access network link employing centralized light generation, colourless optical network unit (ONU) and a reconfigurable optical add/drop multiplexer (ROADM). The architecture of ONU is based on a reflective semiconductor optical amplifier (RSOA). The ROADM is constructed with thermally tuned micro-ring resonators. We present the results of transmission experiments and switching time measurement, which prove the concept of a transparent link with flexible bandwidth on-demand provision using cost-efficient elements.