Marco Camera

Beyond 100Gbit/s: System implications towards 400G and 1T

400G and 1Tbit/s optical transmission will surely benefit from the advances in modulation techniques developed for 100Gbit/s. However, it is required a profound system re-thinking to realize transmission beyond 100G over long-haul wavelength-switched networks.

Analysis of Crosstalk in Mixed 43 Gb/s RZ-DQPSK and 10.7 Gb/s DWDM Systems at 50 GHz Channel Spacing

In DWDM field experiments over 1047 km of standard fiber and in simulations we analyze the impact of crosstalk on a 43 Gb/s RZ-DQPSK channel both by 10.7 Gb/s OOK and 43 Gb/s RZ-DQPSK neighbors at 50 GHz channel spacing.

Experimental Analysis of the Power Auto-Correlation-Based Chromatic Dispersion Estimation Method

We experimentally investigate the performance of the signal power autocorrelation-based method for chromatic dispersion (CD) estimation in a polarization-multiplexing quadrature phase-shift keying (PM-QPSK) 100G coherent optical system conveying optical channel transport unit level-4 (OTU4) frames. It is shown that the typical laboratory setup, where the signal components are generated from delayed versions of the same pseudorandom binary sequence (PRBS), is inadequate for experimental validation because of artifacts in the signal auto-correlation function. This problem is circumvented by the use of a commercial line card transporting independent data sequences. The algorithm is used to estimate accumulated CD values from 0 to 50 000 ps/nm under up to 80-ps differential group delay (DGD). We further evaluate its convergence properties in terms of the length of the sample vector required for correct CD estimation and address the hardware resource requirements. The CD-shifted version of the algorithm yielded a maximum estimation error of 186 ps/nm in all tested conditions.

100GbE optical transport, appropriate modulation formats, and impact on deployed transport networks

We review the system requirements for 100 GbE optical transport and compare possible technical solutions. Our experience, derived from modeling, laboratory experiments and field trials on deployed transport networks is presented.

High power, narrow linewidth, low noise, integrated CMOS tunable laser for long haul coherent applications

An integrated-CMOS-tunable-laser with 15-dBm output power is presented. Fabrication is realized in commercial CMOS foundry. Laser shows high power, low RIN, and ultra-narrow linewidth. Performance over fiber is comparable with best-in-class, market-leading ITLA, proving suitability for long haul coherent applications.

Experimental experiences in high speed DQPSK transmission

Field and laboratory experiments show RZ-DQPSK being a suitable format for 40Gb/s long haul transmission also in mixed rate systems. Trials demonstrate transmission well beyond 1000km for non-ideal fiber spans at higher loss and PMD.

43Gb/s RZ-DQPSK Field Upgrade Trial in a 10Gb/s DWDM Ultra-Long-Haul Live Traffic System in Australia

43 Gb/s upgrade possibility of two existing DWDM links of >1100 km length between Melbourne and Sydney carrying live 10 Gb/s line traffic has been demonstrated. The trial showed a smooth 43 Gb/s introduction with >6 dB of margin and high performance stability.

Field Trial to Upgrade an Existing 10 Gbit/s DWDM Link by 40 Gbit/s RZ-DQPSK Channels

Data rates generated in the access network by new services and customer demand on triple play influence on the transmission capacity and flexibility of the transport network. A field trial to upgrade an existing DWDM link with 10 Gbit/s RZ- and NRZ-channels by 40 Gbit/s RZ-DQPSK-channels was performed on a link consisting of legacy G.652 fibre with two ROADM and EDFA amplification only. The field link had a length of 1047 km. To obtain a high spectral efficiency of the 40 Gbit/s transport the channel spacing was reduced from 100 GHz to 50 GHz. We investigated channel crosstalk for 50 GHz and 100 GHz channel spacing, mixed types of neighbour channels, PMD and chromatic dispersion tolerance which influence on maximum transparent transmission length and signal quality of the 40 Gbit/s signal in a field experiment.

Implementation and testing of a ASK polarization-independent coherent receiver for UDWDM-PON

This paper presents the implementations and test results of the novel polarization-independent receiver for ASK format, realized in the framework of COCONUT FP7 Project. COCONUT exploits low-cost optical components and simple electronics, so that the cost of typical line terminals would be affordable to the end-users. Among the different technical approaches considered within the project; we focus here on the solutions based on simple OOK-NRZ format. We developed an original improvement of the conventional phase-diversity coherent detection schemes, providing for polarization independent operations without doubling the receiver structure. As a result we demonstrated that polarization-independent coherent detection is feasible within the constraint of limited cost typical of passive access networks. The developed receivers can allow for high-power budget (> 45 dB and ultra-dense WDM operation (6.25 GHz grid).

Flexible-sense optical transmission

We present a platform for the optical interconnection of traffic nodes where the sense of transmission is exploited as an additional degree of flexibility. Implementation of the optical arrangement is shown. The requirements about the negotiation of the available resources, such as fibers and wavelengths, are discussed. We evaluate the implications of flexible-sense transmission in terms of cost, power and reach, under realistic assumptions of traffic peak-to-average bandwidth ratio and degree of asymmetry.