Akram Akrout

60 GHz radio-over-fiber technologies for broadband wireless services [Invited]

Some of the work carried out within the European integrated project Integrated Photonic mm-Wave Functions for Broadband Connectivity (IPHOBAC) on the development of photonic components and radio-over-fiber technologies for broadband wireless communication is reviewed. In detail, 60 GHz outdoor radio systems for >10 Gbits/s and 60 GHz indoor wireless systems offering >1 Gbit/s wireless transmission speeds are reported. The wireless transmission of uncompressed high-definition TV signals using the 60 GHz band is also demonstrated.

Low noise performance of passively mode locked quantum-dash-based lasers under external optical feedback

We report on a systematic investigation of the effect of external optical feedback on 17 GHz passively mode-locked two-section lasers based on InAs/InP quantum dashes emitting at 1.58 μm. Narrowing of mode-beating linewidth down to a record value of ∼500 Hz is demonstrated over a large operating range.

Separate Error-Free Transmission of Eight Channels at 10 Gb/s Using Comb Generation in a Quantum-Dash-Based Mode-Locked Laser

We report on comb generation at 1.55 mum using a mode-locked quantum-dash-based laser. A flat optical spectrum with a ~10-nm width consisting of eight 100-GHz-spaced channels is demonstrated. Separate error-free transmission of each channel is achieved at 10 Gb/s over 50-km-long single-mode fiber. Compared to an ideal external cavity continuous-wave laser, a penalty of only 1.5 dB is measured for each filtered channel. This is attributed to the higher relative intensity noise level of a filtered mode.

Error-free transmission of 8 WDM channels at 10 Gbit/s using comb generation in a quantum dash based mode-locked laser

Error-free transmission over 50 km single mode fiber of 8 WDM ITU channels with 100 GHz channel spacing is demonstrated at 10 Gbit/s by using comb generation in a quantum dash mode-locked laser.

Low-timing-jitter all-optical clock recovery for 40 Gbits/s RZ-DPSK and NRZ-DPSK signals using a passively mode-locked quantum-dot Fabry–Perot semiconductor laser

We investigate experimentally all-optical clock recovery for return-to-zero (RZ) and nonreturn-to-zero (NRZ) differential phase-shift keying (DPSK) signals at 40 Gbits/s using a passively mode-locked quantum-dot Fabry-Perot (QD-FP) semiconductor laser. The QD-FP laser exhibits a beat spectrum linewidth of 80 kHz, which enables a recovered clock signal with a root-mean-square timing jitter of 160 fs for the RZ-DPSK signal and 240 fs for the NRZ-DPSK signal. The timing jitter of the recovered clock signal is characterized for different values of the input signal power and the input signal optical signal-to-noise ratio.

Characterization of All-Optical Clock Recovery for 40 Gb/s RZ-OOK and RZ-DPSK Data Using Mode-Locked Semiconductor Lasers

We investigate the characteristics of all-optical clock recovery for return-to-zero differential phase-shift keying (RZ-DPSK) and return-to-zero on-off keying (RZ-OOK) signals at 40 Gb/s using mode-locked semiconductor lasers. Two mode-locked lasers with different configurations, a bulk active layer distributed Bragg reflector laser and a quantum-dot active layer Fabry-Perot laser, are used in the experimental investigation. The results reveal the implications of the input signal power, beat spectrum linewidth of the mode-locked laser, and intensity modulation on the jitter characteristics of the recovered clock signal.

Optimization of a 54.8 GHz coupled opto-electronic oscillator through dispersion compensation of a mode-locked semiconductor laser

Dispersion impact on electrical signal generation at 54.8 GHz of a quantum dash (QDs) mode-locked Fabry-Perot (FP) lasers emitting at 1.55 mum has been measured. Optimum fibre length values that correspond to dispersion compensation have been found. For these optimal conditions a pulse width of 480 fs has been measured. These optimum fibre length values have been applied to the integration of two architectures of phase noise reduction schemes: a coupled opto-electronic oscillator (COEO) with a single self-injection loop associated to a self-phase-locked loop (PLL) and a dual loop COEO. A phase noise reduction of more than 30 dB at an offset frequency of 20 kHz has been obtained for the second architecture.

All-optical clock recovery using a quantum-dash Fabry-Pérot laser

The performance of a quantum-dash Fabry-Pérot laser is experimentally characterized for 40 Gb/s RZ-DPSK and NRZ-DPSK clock recovery, 40 Gb/s RZ-OOK all-optical 3R regeneration, and 160 Gb/s OTDM sub-harmonic clock recovery.

Application of a passively mode-locked quantum-dot Fabry-Perot laser in 40 Gb/s all-optical 3R regeneration

The application of a mode-locked quantum-dot Fabry-Perot (QD-FP) laser in a wavelength preserving all-optical 3R regenerator is demonstrated at 40 Gb/s. The 3R regenerator consists of a QD-FP laser for low-timing jitter clock recovery, cross-phase modulation based retiming, and self-phase modulation based reshaping. The performance of the alloptical 3R regenerator is assessed experimentally in terms of the Q-factor, timing jitter and bit-error ratio.

Spectrum filtering and pulse compression of Quantum-Dash mode-locked lasers emitting at 1.55 μm

2.2 ps pulses at 42.72 GHz after spectrum filtering and 1.1 ps pulses after chirp compensation are generated using mode-locked laser diodes based on 1.55 mum quantum dash.