Kamel Merghem

A multi-GHz chaotic optoelectronic oscillator based on laser terminal voltage

A multi-GHz chaotic optoelectronic oscillator based on an external cavity semiconductor laser (ECL) is demonstrated. Unlike the standard optoelectronic oscillators for microwave applications, we do not employ the dynamic light output incident on a photodiode to generate the microwave signal, but instead generate the microwave signal directly by measuring the terminal voltage V(t) of the laser diode of the ECL under constant-current operation, thus obviating the photodiode entirely.

Resonance fluorescence revival in a voltage-controlled semiconductor quantum dot

We demonstrate systematic resonance fluorescence recovery with near-unity emission efficiency in single quantum dots embedded in a charge-tunable device in a wave-guiding geometry. The quantum dot charge state is controlled by a gate voltage, through carrier tunneling from a close-lying Fermi sea, stabilizing the resonantly photocreated electron-hole pair. The electric field cancels out the charging/discharging mechanisms from nearby traps toward the quantum dots, responsible for the usually observed inhibition of the resonant fluorescence. Fourier transform spectroscopy as a function of the applied voltage shows a strong increase of the coherence time though not reaching the radiative limit. These charge controlled quantum dots act as quasi-perfect deterministic single-photon emitters, with one laser pulse converted into one emitted single photon.

Optimized Modulation Bandwidth and Henry Factor of Fabry-Perot InAs/InP Quantum Dash Based Ridge Waveguide Lasers for Access/Metro Networks

Unprecedented high modal gain of ~100 cm-1 is obtained for an optimized structure based on InAs/InP quantum dashes (QDash) emitting at 1.55 μm. This structure allows achieving ~10 GHz direct modulation bandwidth. P-type doping reduces the Henry factor value down to 2.7.

InAs/InP quantum dot mode-locked lasers grown on (113)B InP substrate

We report for the first time the passive mode-locking of single section Fabry-Perot (FP) lasers based on InAs quantum dots grown on (113)B InP substrate. Devices under study are a 1 and 2 mm long laser diodes emitting around 1.58 μm. Self-starting pulses with repetition rates around 39 and 23 GHz and pulse widths down to 1.5 ps are observed after propagation through a suitable length of single-mode fiber for intracavity dispersion compensation.