Guy Aubin

Short pulse generation using a passively mode locked single InGaAsP/InP quantum well laser

We report on subpicosecond pulse generation using passively mode locked lasers (MLL) based on a low optical confinement single InGaAsP/InP quantum well active layer grown in one epitaxial step. Systematic investigation of the performances of two-section MLLs emitting at 1.54 microm evidenced pulse width of 860 fs at 21.31 GHz repetition rate, peak power of approximately 500 mW and a time-bandwith product of 0.57. A 30 kHz linewidth of the photodetected radio-frequency electrical spectrum is further demonstrated at 21 GHz which is, to our knowledge, the lowest value ever reported for a quantum well device.

Comparison of light- and heavy-ion-irradiated quantum-wells for use as ultrafast saturable absorbers

We have compared light- and heavy-ion irradiation of InGaAs/InAlAs multiple-quantum wells for ultrafast saturable absorption applications. Under heavy-ion impacts, defect clusters were produced, as observed via transmission electronic microscopy. By contrast, in proton-irradiated samples, only point defects were formed. Nonlinear absorption measurements were performed with excitonic resonance pumping. The relaxation time of absorption saturation (minimum value 2 ps) did not depend on the irradiating ion, and was practically independent of the pulse repetition rate (up to 10 GHz) and optical excitation fluence (0.1 mJ/cm2). We conclude that irradiating multiple-quantum wells with light ions is as effective as using heavy ions, when fabricating ultrafast saturable absorber devices operating at high bit rate and near bandedge wavelength.

40 Gbit/s optical 2R regenerator based on passive saturable absorber for WDM long-haul transmissions

A semiconductor saturable absorber based on ion-irradiated quantum-well vertical cavity is implemented in a 40 Gbit/s dispersion-managed RZ loop, yielding a Q-factor of 13 dB and 11.3 dB at 7600 km distance in single-channel and in WDM environment with five 200 GHz-spaced 40 Gbit/s channels, respectively.

Stability of Optical Frequency Comb Generated With InAs/InP Quantum-Dash-Based Passive Mode-Locked Lasers

In this paper, we present a systematic investigation of passive mode-locked InAs/InP quantum-dash lasers in terms of frequency and timing stability. Mode-locking features are analyzed using the frequency domain approach based on the concept of supermodes. It is shown that the phase of adjacent longitudinal modes is correlated over 1.3-THz frequency span. The observed strong coherence between modes enables low timing jitter and a long-term stability of the repetition rate frequency within 5×10-8 over 100 s.

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.

Subpicosecond pulse generation from a 1.56 μm mode-locked VECSEL

Near-transform-limited subpicosecond pulses at 1.56 μm were generated from an optically pumped InP-based vertical-external-cavity surface-emitting laser (VECSEL) passively mode-locked at 2 GHz repetition rate with a fast InGaAsNSb/GaAs semiconductor saturable absorber mirror (SESAM). The SESAM microcavity resonance was adjusted via a selective etching of phase layers specifically designed to control the magnitude of both the modulation depth and the intracavity group delay dispersion of the SESAM. Using the same VECSEL chip, we observed that the mode-locked pulse duration could be reduced from several picoseconds to less than 1 ps with a detuned resonant SESAM.

A passive all-optical semiconductor device for level amplitude stabilization based on fast saturable absorber

A high-speed saturable-absorber-based device (response time below 2.5ps) providing a significant amplitude stabilization is demonstrated. The experimental results allow estimating that the amplitude fluctuations of the output should be reduced by about 90% compared to the input fluctuations, within the input power range of (5–18μJ∕cm2). This device has been studied in view of its possible use for bit-1 noise reduction. When combined with a state-of-art saturable absorber device, this could provide a simple and compact scheme for the complete reamplification and reshaping regeneration of digital optical signals.

Ultrafast InGaAs/InGaAlAs multiple-quantum-well electro-absorption modulator for wavelength conversion at high bit rates

We report on InGaAs/InGaAlAs electro-absorption modulators for ultrafast all-optical signal processing. The structure design is based on the use of small conduction and valence band offsets. Switching windows as short as 5 ps for a 2 V applied reverse bias have been obtained by cross-absorption modulation.

The Dual-Electroabsorption Modulated Laser, a Flexible Solution for Amplified and Dispersion Uncompensated Networks Over Standard Fiber

We propose here a monolithically integrated dual RF access electroabsorption-modulated laser called D-EML for the generation of optical single-sideband signal for both nonreturn to zero and orthogonal frequency division multiplexing formats. The benefits of optical single-sideband over double sideband in terms of resilience against chromatic dispersion effects are presented for high-bit rate intensity modulation/direct detection transmissions over standard single mode fiber in the C-band. Both simulation and experimentation exhibit transmission distance enhancement in the case of dual modulation of the D-EML, i.e., in optical single-sideband configuration, making this optical source an interesting solution because of its low-cost, low-size, and reasonable-power consumption.

12.5GB operation of a novel monolithic 1.55µm BPSK source based on prefixed optical phase switching

Novel optical phase switching BPSK transmitter was used to transmit 12.5GB signal over 40km. Speed scalability, ultra-small footprint and low power drive of the monolithic circuit are attractive for advanced format migration towards low-cost applications.