All optical systems for terabit network era

The continuous growth of the network capacity demand drives the development of the optical fiber networks. Since optical super-channels carrying multi- Terabit/s transmissions are the next evolution of the optical links, future transmitters and receivers systems will be required to handle vast volume of information while maintaining reasonable power consumption and cost. In addition, when point-to-point links are approaching the fundamental limit of standard fiber, the efficient use of the entire transmission window for optical networks will only be achieved through flexible superchannels compatible with flexible optical nodes. This thesis describes the research work carried out to investigate the future optical systems that will support the Terabit era networks. All-optical systems are presented, allowing for high spectral efficiency in future networks, from the comb sources to the optical nodes. The following manuscript firstly reports on the development of optical combs based on external modulators to provide transmitters with a large number of optical carriers. Then, the implementation of an experimental all-optical super-channel through the use of optical signals and wavelength manipulations is described. Finally, a novel all-optical node called Terabit Interferometric add, Drop, and Extract (TIDE) is presented. With a management of the super-channel components in the optical domain, the optical node offers transparency and flexibility while maintaining the high spectral efficiency of the super-channel carrying links. An optical frequency comb source was developed, generating a high quality 9-line comb with a spectral flatness 20 dB. A single Mach-Zehnder modulator was driven with a low power multi- harmonic electrical signal. Furthermore, a large 36 line comb was obtained by the addition of a two cascaded modulators comb source driven with a 90 GHz signal The implementation of an alloptical Orthogonal Frequency Division Multiplexing (OFDM) super-channel, using a high quality single sideband modulation scheme based on a dual-parallel Mach-Zehnder modulator, allowed for the development and test of the all-optical TIDE node. The interferometer-based structure was capable of managing (add, drop, and extract) channel from a super-channel strictly in the optical domain. In this manuscript, we prove that it is possible to extract channels even with overlapping spectrum super-channel aggregation for both single and dual quadrature modulation formats

Experimental implementation of an all-optical interferometric drop, add, and extract multiplexer for superchannels

We present the experimental implementation of an all-optical ROADM scheme for routing of an individual subchannel within an all-optical OFDM superchannel. The different functions required of optical node were demonstrated using interferometric technique with the extraction, drop, and addition of individual subchannel in a ten subchannels optically aggregated signal. The scheme we reported enables a fully flexible node compatible with future terabit per second superchannel transmission

Experimental demonstration of an all-optical interferometric drop, add, and extract multiplexer for OFDM super-channel

The experimental implementation of an all-optical node able of routing a channel contained in an all-optical OFDM super-channel is presented. The extract function is performed through channel selection, reshaping and interferometric suppression

Persistent neutrophil to lymphocyte ratio >3 during treatment with enzalutamide and clinical outcome in patients with castration-resistant prostate cancer

The baseline value of neutrophil to lymphocyte ratio (NLR) has been found to be prognostic in patients with metastatic castration resistant prostate cancer (CRPC). We evaluated the impact of baseline NLR and its change in patients receiving enzalutamide. We included consecutive metastatic CRPC patients treated with enzalutamide after docetaxel and studies the change of NLR (>3 vs ≤3) after week 4 and 12 weeks. Progression-free survival (PFS), overall survival (OS) and their 95% Confidence Intervals (95% CI) were estimated by the Kaplan-Meier method and compared with the log-rank test. The impact of NLR on PFS and OS was evaluated by Cox regression analyses and on prostate-specific antigen response rates (PSA RR; PSA decline >50%) were evaluated by binary logistic regression. Data collected on 193 patients from 9 centers were evaluated. Median age was 73.1 years (range, 42.8–90.7). The median baseline NLR was 3.2. The median PFS was 3.2 months (95% CI = 2.7–4.2) in patients with baseline NLR >3 and 7.4 months (95% CI = 5.5–9.7) in those with NLR ≤3, p < 0.0001. The median OS was 10.4 months (95% CI = 6.5–14.9) in patients with baseline NLR >3 and 16.9 months (95% CI = 11.2–20.9) in those with baseline NLR ≤3, p < 0.0001. In multivariate analysis, changes in NLR at 4 weeks were significant predictors of both PFS [hazard ratio (HR) 1.24, 95% confidence interval (95% CI) 1.07–1.42, p = 0.003, and OS (HR 1.29, 95% CI 1.10–1.51, p = 0.001. A persistent NLR >3 during treatment with enzalutamide seems to have both prognostic and predictive value in CRPC patients

Optical Sinc-Shaped Nyquist Pulse Source Based on a Single Mach-Zehnder Modulator

We present a precise and flexible Sinc-shaped Nyquist pulse source based on a single Mach-Zehnder modulator. The use of multi-harmonic RF signals provides direct control on the Nyquist pulse train generation. The variable comb source is demonstrated by selecting the number of RF components used to drive the optical modulator, leading from 3 to 9 comb lines. Furthermore, different operating points are reported to show the multi-harmonic comb generator potential to provide near-perfect Nyquist pulse source with pure rectangular optical spectrum or with minimized insertion loss

Flexible Width Nyquist Pulse Based on a Single Mach-Zehnder Modulator

We present a Nyquist pulse generation technique based on a single Mach-Zehnder modulator driven by a multi-harmonic electrical signal. The direct control of the RF components yields a range of 10 GHz sinc-shaped pulse train

Reconfigurable Filter-free Sinc-shaped RF Photonic Filters Based on Rectangular Optical Frequency Comb

We demonstrate reconfigurable sinc-shaped RF photonic filters based on rectangular optical frequency comb synthesized from cascaded modulators. Simplicity of the approach and flexibility in bandwidth for fixed free-spectral-range is shown. Phase response is also investigated

Impact of Raman amplification on a 2 Tb/s coherent WDM system

The impact of hybrid erbium-doped fiber amplifier (EDFA)/Raman amplification on a spectrally efficient coherent-wavelength-division-multiplexed (CoWDM) optical communication system is experimentally studied and modeled. Simulations suggested that 23-dB Raman gain over an unrepeatered span of 124 km single-mode fiber would allow a decrease of the mean input power of ~6 dB for a fixed bit-error rate (BER). Experimentally we demonstrated 1.2-dB Q-factor improvement for a 2-Tb/s seven-band CoWDM with backward Raman amplification. The system delivered an optical signal-to-noise ratio of 35 dB at the output of the receiver preamplifier providing a worst-case BER of 2 × 10 -6 over 49 subcarriers at 42.8 Gbaud, leaving a system margin (in terms of Q -factor) of ~4 dB from the forward-error correction threshold

All-optical OFDM and distributed Raman amplification:challenges to enable high capacities and extend reach

We review recent advances in all-optical OFDM technologies and discuss the performance of a field trial of a 2 Tbit/s Coherent WDM over 124 km with distributed Raman amplification. The results indicate that careful optimisation of the Raman pumps is essential. We also consider how all-optical OFDM systems perform favourably against energy consumption when compared with alternative coherent detection schemes. We argue that, in an energy constrained high-capacity transmission system, direct detected all-optical OFDM with `ideal' Raman amplification is an attractive candidate for metro area datacentre interconnects with ~100 km fibre spans, with an overall energy requirement at least three times lower than coherent detection techniques

Exceeding the nonlinear-shannon limit using Raman laser based amplification and optical phase conjugation

We demonstrate that a combination of Raman laser based amplification and optical phase conjugation enables transmission beyond the nonlinear-Shannon limit. We show nonlinear compensation of 7x114Gbit/s DP-QPSK channels, increasing system reach by 30%