Ioannis Tsalamanis

Experimental demonstration of cascaded AWG access network featuring bi-directional transmission and polarization multiplexing

We present the first experimental demonstration of a bidirectional cascaded arrayed-waveguide grating (AWG) access network combining one NxN AWG in the central office with multiple 1xN AWGs at the distribution points, such as to individually address N(2) users with only N wavelengths. Downstream and upstream data share the same optical path. BER curves were measured using 2.5Gb/s data stream in each direction, and error free transmission achieved for downstream and upstream, with only 0.3dB power penalty for simultaneous transmission. The addition of two orthogonal polarization-multiplexed channels per wavelength doubled the number of possible end users. Error free transmission was achieved with simultaneous upstream and downstream transmission of a composite signal featuring eight 2.5Gb/s channels (2 polarizations x 4 wavelengths).

Polarization dependent loss and temperature fluctuations effect on degree of orthogonality in polarization multiplexed arrayed waveguide grating based distribution networks

We analyze the effect of arrayed-waveguide grating (AWG) polarization dependent loss (PDL) on the orthogonality between polarization multiplexed channels in a cascaded AWG-based access network topology. For a single AWG, with 0.5-dB PDL, we find an experimental degradation in polarization multiplexing orthogonality to be a maximum of 0.9/spl deg/, in good agreement with theory. In addition, experimental, and numerically simulated maps of orthogonality degradation versus input states of polarization (SOP) are investigated and found to agree well. Consequently, we analyze the effect of cascaded AWGs and again find that the experimental result of maximum 2.9/spl deg/ degradation in polarization multiplexing orthogonality closely matches theoretical predictions. Thermal variations are also found to have similar effects for all SOPs, with a measured degradation in orthogonality of up to 2.5/spl deg/ for a temperature range between 20/spl deg/C and 55/spl deg/C. Overall, this indicates the robustness of polarization multiplexing, making it applicable for appropriate deployment in bandwidth/user-enhanced access networks based on cascaded AWGs.

Graeco-Latin-routed, self-wrapping, FSR-interleaved, AWG-based access network

Feature Issue on Passive Optical Network Architectures and TechnologiesWe describe, to the best of our knowledge, a novel WDM-TDM switched access network architecture featuring cascaded 16×16 and 1×32 arrayed waveguide gratings (AWGs), such that the AWG free spectral ranges (FSRs) have been matched to provide cascaded, cyclical, Graeco-Latin-routing protocols for downstream and upstream routing. In particular, use of FSR-multiplexed wavelengths allows greatly reduced cross talk between upstream and downstream signals and also doubling of the available network bandwidth capacity, while maintaining the same N×N AWG in the central office. Alternatively, this allows significant increase in the number of end users served by the network. We provide theoretical and simulation studies of our bidirectional access network topology, and experimental proof of principal results. Three sets of simulations with data rates from 2.5, 5.0, and 10.0Gbits/s have been performed for downstream and upstream transmissions. For the experimental part, eight ITU wavelengths were multiplexed at the exchange point and successfully transmitted at 2.5Gbits/s for simultaneous bidirectional transmission. Bit-error-rate measurements show error-free transmission is achievable for both directions with minimal cross talk between the channels.

VDSL transmission over a fiber extended-access network

Feature Issue on Optical Access Networks (OAN) We describe two schemes developed to carry very-high-data-rate DSL (VDSL) signals over a fiber to the cabinet architecture for the upgrade of legacy copper networks. The first technique exploits the subcarrier bandwidth of uncooled semiconductor lasers for the transmission of multiple VDSL signals by using inexpensive interfacing hardware in the optical network unit (ONU). With a hybrid fiber-copper link comprising 100 m of twisted-pair copper cable and as much as 45 km of single-mode fiber, data transmission comparable with that for fiber to the home is achieved. In an extension to this design we demonstrate a system using a reflective semiconductor optical amplifier in a carrierless remote ONU configuration. Such a design might provide wavelength agility in the fiber access network for signal routing or active bandwidth allocation.

Study of Hybrid Cascaded AWG-based Access Network Topology

We describe an upgrade scenario from current passive optical networks (PON) to wavelength routed fibre-to-the-home (FTTH) networks. The theoretical and experimental study of a bidirectional access network topology based on cascaded arrayed waveguide gratings (AWG) is presented. By combining a 16times16 AWG in the exchange point and multiple 1times16 AWGs in the distribution points, N2 users can be addressed when N wavelengths are transmitted. 16 ITU wavelengths have been multiplexed at the exchange point and successfully transmitted at 2.5 Gb/s data rates for simultaneous bidirectional transmission. Bit error rate measurements have shown error free transmission is achievable for both directions and minimal crosstalk between the channels can be noticed in the retrieved eye diagrams

A FSR-Interleaved, Self-Wrapping, Multiple-Cascaded AWG-based WDM Access Network

We describe a WDM:TDM-swapped access network architecture, featuring AWG-based double-cascade downstream and triple-cascade upstream operation. Cyclical Latin-routing protocols allow FSR-interleaving for capacity-multiplication via self-wrapping 16x16 and 1x32 central office AWGs. 2.5 Gb/s/wavelength performance was experimentally verified.

VDSL transmission over Latin routed DWDM optical access networks

We present a novel architecture for sub-carrier multiplexed VDSL transmission utilising cascaded arrayed-waveguide grating optical access network. In particular, triple play was achieved with both DMT and QAM based VDSL modems.

Interoperability of Last Mile Access Technologies over a Passive Optical Ring Network: Results of the MUSE Demonstration

We demonstrate simultaneous operation of FWA, FTTP and FTTCab/DSL solutions over a common passive CWDM ring network platform; verifying the potential coexistence of multiple deployment scenarios for high bandwidth delivery in future access networks.