Elisabeth Gaumont-Goarin

Tapered active stripe for 1.5‐μm InGaAsP/InP strained multiple quantum well lasers with reduced beam divergence

We propose and demonstrate the application of an intracavity horizontally tapered (in width) active stripe to adiabatically reduce the output beam divergence of a 1.48‐μm InGaAsP/InP strained quantum well laser. We achieve far‐field full width at half‐maximum divergences as low as 13° together with 100 mW emitted power into stable single transverse mode and 400 mA driving current. Maximum coupling efficiency to lensed single mode fiber of 73% is obtained.

Integrated laser-waveguide structures using selective area intermixing

Photonic integrated circuits such as integrated laser-modulators require side by side planar areas with differential bandgap. Structures grown in single step epitaxy permit very efficient coupling between the different regions of the device. This has been demonstrated by selective area growth (SAG) using metalorganic vapor phase epitaxy for laser-modulator applications at 1.55 /spl mu/m. On the other hand, selective area intermixing (SAI) appears as a promising technique to control the differential wavelength between two regions. Such a technique provides maximum coupling efficiency (100%) between two sections of different band gap and leads to a reduction of the number of growth steps. In this paper, we report on the optical and electrical properties of InGaAsP/InP compressive strained multiple quantum well (MQW) laser-guide structures obtained by SAI under phosphorus over pressure in a vacuum sealed quartz ampoule. In this technique, the linear time dependence of the photoluminescence (PL) blue shift due to group V elements interdiffusion allow us to control the differential wavelength between dielectric capped and uncapped areas. The interdiffusion is strongly reduced in the dielectric capped areas and results in a low PL blue shift. Low threshold current densities are obtained in both areas even for a PL blue shift as large as 170 nm. In addition, optical intensity modulators based on the quantum confined stark effect (QCSE) exhibit high extinction ratio of -30 dB (/spl lambda/=1.55 /spl mu/m) with reverse driving voltage of about 1.2 V.<<ETX>>

Electro-refractive effect and absorption in an InGaAs/InP superlattice structure

Results on electro-refraction variations and waveguide absorption in InP-based superlattice modulators are presented. The method employed to measure these parameters using Fabry-Pe/spl acute/rot resonances versus wavelength is described. Effective index variation as high as 1.7 10/sup -3/ has been obtained, corresponding to a 1.9 10/sup -2/ refractive index variation in multiple quantum well or superlattice structures.<<ETX>>

Transition time and turn‐on jitter of optically triggered bistable lasers incorporating a proton bombarded absorber

Recently, we have demonstrated 1 Gbit/s error free operation of an optically triggered bistable laser, which is the highest bit‐rate operation ever reported without electrical reset. This is achieved by using proton bombardment of the absorber section which induces a reduction of the carrier lifetime in this section. This letter presents the first experimental results on the transition time and the turn‐on jitter of an optically triggered bistable laser incorporating a proton bombarded absorber section. Current injection conditions that minimize the overall transition time have been derived. It has been found that for a constant current in one active section, the rise time decreases, but the fall time increases with injection current in the other section. An optimal current value can then be found to minimize the overall transition time. The measured turn‐on jitter and relaxation oscillation period decrease with increasing injection current, in good agreement with theoretical predictions.

High FM Bandwidth of a DBR laser with electro-optical tuning sections

Distributed-Bragg-reflector (DBR) laser diodes (LDs) look attractive for frequency modulation (FM) light sources.1 Nevertheless, they suffer from limitation of the — 3-dB cutoff frequency when the phase section is modulated by carrier injection.2 Taking into account high index variations measured on a superlattice (SL) modulator when it is reverse biased,3 we realized a high-frequency voltage-controlled FM source with a butt-jointed intracavity SL modulator in a multiple-quantum-well (MQW) DBR laser.

Proton bombardment technique for high speed (>1 Gbit/s) 4 section bistable DBR wavelength converter

Wavelength conversion is a key function for optical switching using wavelength routing. Among the different solutions (gain saturation in semi-conductor amplifiers or in DBR lasers) bistable lasers based on saturable absorption are attractive with their signal reshaping capability but they have been limited in speed by the carrier lifetime of the absorption section. To overcome this limitation, we have optimised a proton bombardment technique of the saturable absorber and applied it to the realisation of (4 section) high speed bistable DBR lasers. Wavelength conversion is thus demonstrated at 1 Gbit/s together with Extinction Ratio regeneration.<<ETX>>

Three-section PDBR lasers with narrow spectral linewidth (less than 10 Mhz) under tuning

The spectral linewidth behavior under wavelength tuning of tunable lasers is a key point as far as local oscillator applications for a coherent multichannel (CMC) system is foreseen. At this time, spectral linewidth broadening under tuning operation has been observed and this is the main problem for monolithic tunable lasers as well as for DBR type lasers1 or TTG2 structures.