Christophe Gosset

Subpicosecond pulse generation at 134GHz using a quantum-dash-based Fabry-Perot laser emitting at 1.56μm

We demonstrate passive mode locking in one-section monolithic semiconductor laser diodes based on quantum-dash active layer at very high repetition rate in the 1.5μm window. Transform-limited pulses are generated at 134GHz with subpicosecond width, without any pulse compression scheme. A 50kHz linewidth of the radio-frequency spectrum is also demonstrated at 42GHz, the lowest value reported for any passively mode-locked semiconductor laser. We further show that the saturable absorption section in two-section devices has no significant impact on the mode-locking behavior.

Block-Wise Digital Signal Processing for PolMux QAM/PSK Optical Coherent Systems

In polarization multiplexing based coherent optical transmission, two main kinds of impairements have to be counter-acted: 1) the inter-symbol interference generated by the chromatic dispersion and the polarization mode dispersion and 2) the frequency offset. Usually adaptive approaches are carried out to mitigate them. Since the channel is very slowly time-varying, we propose to combat these impairements by using block-wise methods. Therefore, we introduce two new algorithms: the first one is a block-wise version of blind time equalizer (such as CMA), and the second one estimates the frequency offset in block-wise way. These algorithms are suitable for PSK and QAM constellations. By simulation investigations, we show that they outperform the standard approach in terms of convergence speed only at a moderate expense of computational load. We also experimentally evaluate their performance using 8-PSK real data traces and off-line processing which takes into account other physical impairments such as phase noise and non-linear effects.

Phase-amplitude characterization of a high-repetition-rate quantum dash passively mode-locked laser

We apply a novel phase-amplitude method to a 42.2 GHz one-section quantum dash-based passively mode-locked laser. This new method relies on the measurement of the spectral phase of the longitudinal modes by autocorrelation analysis.

Extinction ratio improvement and wavelength conversion based on four-wave mixing in a semiconductor optical amplifier

We have demonstrated an extinction ratio improvement of more than 3 dB at 2.5 Gb/s with a method based on four-wave mixing in a semiconductor optical amplifier. A wavelength conversion and a data format conversion from nonreturn-to-zero (NRZ) to return-to-zero (RZ) have been simultaneously achieved.

Dispersion Compensation-Free IM/DD SSB-OFDM Transmission at 11.11 Gb/s Over 200 km SSMF Using Dual EML

We report on a novel optical single sideband-orthogonal frequency division multiplexing system for access and metro networks based on a single, low cost dual electro-absorption modulated laser. The experimental results successfully demonstrate transmissions at 11.11 Gb/s over 200 km uncompensated standard single mode fiber through intensity modulation and direct detection.

Dual-polarization multi-band OFDM versus single-carrier DP-QPSK for 100 Gb/s long-haul WDM transmission over legacy infrastructure

We experimentally compare the performance of coherent dual-polarization multi-band OFDM (DPMB-OFDM) and QPSK (DP-QPSK) for 100 Gbps long-haul transport over legacy infrastructure combining G.652 fiber and 10 Gbps WDM system. We show that DP-MB-OFDM and DP-QPSK have nearly the same performance at 100 Gbps after transmission over a 10x100 km fiber line.

100 Gb/s coherent optical polarization multiplexed multi-band-OFDM (MB-OFDM) transmission for long-haul applications

The performance of coherent dual-polarization multi-band OFDM (DP MB-OFDM) and coherent single-carrier dual-polarization QPSK (DP QPSK) is experimentally compared for 100 Gb/s long-haul transmissions. It is shown that, after transmission over 1000 km of DCF-free G.652 fiber line, DP MB-OFDM and DP QPSK have nearly the same performance. Furthermore, it is shown based on numerical simulations that DP MB-OFDM is sensitive to the nonlinear inter-band crosstalk effects such as FWM and XPM.

Nondegenerate Four-Wave Mixing in a Dual-Mode Injection-Locked InAs/InP(100) Nanostructure Laser

The nondegenerate four-wave mixing (NDFWM) characteristics in a quantum-dot Fabry-Perot laser are investigated, employing the dual-mode injection-locking technique. The solitary laser features two lasing peaks, which provides the possibility for efficient FWM generation. Under optical injection, the NDFWM is operated up to a detuning range of 1.7 THz with a low injection ratio of 0.42. The normalized conversion efficiency (NCE) and the side-mode suppression ratio (SMSR) with respect to the converted signal are analyzed. The highest NCE of -17 dB associated with a SMSR of 20.3 dB is achieved at detuning of 110 GHz.

Novel cost-effective PON-to-RoF photonic bridge for multigigabit access networks.

Telecommunication operators are investing significant resources in developing passive optical networks (PONs) to meet the increasing capacity requirements. Therefore, wireless transmission has become the bottleneck for the wireless broadband internet access due to the spectrum saturation. This issue can be solved taking advantage of the huge portions of unused spectrum at high-microwave / millimeter-wave (mm-wave) bands, but their generation is power consuming. Radio over fiber (RoF) is a cost-efficient solution for the distribution of high-frequency broadband signals to remote base stations. We present a novel photonic PON-to-RoF bridge based on heterodyning a PON signal with an unmodulated tone generated by an independent laser. The proposed scheme is transparent to modulation format and can generate RF signals in the entire microwave band. The feasibility of the bridge is experimentally shown converting a 2-Gbps orthogonal frequency division multiplexing PON signal using inexepensive distributed feedback lasers, whose phase noise is cancelled employing an envelope detection based mobile terminal.

ElectroAbsorption Modulated Laser Integrated with a Semiconductor Optical Amplifier for 100-km 10.3 Gb/s Dispersion-Penalty-Free Transmission

We report, for the first time, a transmission experiment over standard fiber at 1.55 μ m using an electroabsorption modulated laser (EML) integrated with a semiconductor optical amplifier (SOA). We show clearly that negative pre-chirped signals can be obtained by adjusting both modulator and amplifier driving parameters. Negative chirp operation is evaluated through small-signal chirp measurement as well as through time-resolved dynamic chirp measurement. Signal chirp control at emission enhances transmission and increases optical reach. Thanks to the SOA gain and chirp compensation for modulator loss and chirp, dispersion-penalty-free with clear open eye diagrams over 100 km of optical fiber at 10.3 Gb/s is achieved. A transmission up to 125 km is also obtained. This novel fully integrated EML-SOA is very promising as a high-performance, compact and low-cost optical transmitter for the future access-metropolitan network convergence.