A. Champagne

Global and local effects in gain-coupled multiple-quantum-well DFB lasers

Global and local effects in gain-coupled multiple-quantum-well distributed feedback lasers are analyzed using a new approach that combines a submicrometer two-dimensional analysis together with a longitudinal transfer-matrix calculation. Issues such as complex coupling, the standing wave effect, hole burning, and barrier effects are examined in some detail. It is also shown that, due to the local interactions, the grating contrast is nonuniform along the cavity, leading to the new phenomenon of differential longitudinal spatial hole burning.

Photoelastic effects on the emission patterns of InGaAsP ridge-waveguide lasers

The dielectric window opening in ridge waveguide lasers needed for the ohmic contact is shown to be able to cause appreciable stress deformations of the effective permittivity which defines the waveguide properties of the laser. For edge force values in the range of 40 dyn/ mu m, the emission properties of the laser, namely the near field and the threshold current, start to change. The results indicate that for still higher values, filamentation begins to occur. The numerical results presented use a global self-consistent model of the semiconductor laser and finite-element method for stress-field calculations. >

Capture and escape in quantum wells as scattering events in Monte Carlo simulation

The capture and escape in quantum wells are considered as scattering events in Monte Carlo simulation. Explicit expressions are derived for these interaction rates which depend on carrier initial energy. The expressions are applied to calculate the electron overall capture time in a GRINSCH quantum well at 300 K.

Enhanced carrier injection efficiency from lateral current injection in multiple-quantum-well DFB lasers

A bidimensional simulation shows that the lateral carrier injection in etched active region of multiple-quantum-well DFB lasers represents a large fraction of the injected current, leading to improved carrier homogenization in the wells. This increases the average carrier density substantially and provides a much higher gain for the same injected current, depending on detailed device structure.

Linewidth broadening in a distributed feedback laser integrated with a semiconductor optical amplifier

The problem of the linewidth degradation in systems using distributed-feedback lasers together with strained-layer multi-quantum-well semiconductor optical amplifiers (SOAs) is examined. A modified expression for the linewidth in the case of anti reflection-coated SOA output facets is derived and simulation results are given in the case of output facets with a nonvanishing reflectivity. A numerical model combining finite-element calculations in the transverse x-y plane and a longitudinal model based on the Greens function method is used for that purpose.

Selective TE-TM mode pumping efficiencies for ridge-waveguide lasers in presence of stress

In ridge-waveguide InGaAsP lasers, TE-TM polarization switching with injection current can be caused by the presence of stress in the active layer coming from the deposition of stressed oxide and metallic films on the surface. It is shown that polarization switching takes its origin in the change of the mode pumping efficiency as the current varies. This conclusion has been reached with the help of a comprehensive semiconductor laser model that includes stress effects. Various stress regimes have been identified and it is also shown that the overall stress value in the active layer is the dominant effect, not so much the detailed stress profile. >

Relaxation oscillation frequency of DFB lasers with gain coupling

Using the spatially-dependent rate equations based on the Greens function analysis, we investigate the dependency of the relaxation oscillation frequency on the complex coupling coefficient and other parameters of gain-coupled DFB lasers by simultaneously considering spatial-hole-burning, gain saturation and gain compression. An explicit expression for the relaxation oscillation frequency for DFB lasers including the longitudinal spatial effects has been obtained. It is found that antiphase gain-coupling significantly enhances the local effective differential gain in the gain-coupled DFB laser and hence increases the relaxation oscillation frequency. We have also shown for the first time that the modal linewidth enhancement factor /spl alpha//sub M/ plays an important role in determining the relaxation oscillation frequency of gain-coupled DFB lasers, especially when the built-in index coupling is weak. >

Biaxial stress effects on the TE/TM polarization switching of InGaAsP ridge-waveguide lasers

TE/TM (transverse electric/magnetic) polarization switching in ridge-waveguide InGaAsP lasers is analyzed with due considerations to biaxial stress effects on both the waveguiding and gain properties of the device. The conditions of switching for several models are established. In particular, the gain expression for uniaxial stress is extended to include biaxial stress, and the differences between the different models are presented.<<ETX>>

Fine-scale analysis of gain-coupled MQW DFB lasers

In gain-coupled (GC) multiple-quantum-well (MQW) distributed feedback (DFB) lasers, phenomena on the submicron scale corresponding to quantum-well active regions with etched Bragg gratings have been shown to affect overall laser performance. In this paper we present results combining submicron bi-dimensional modeling with a fine-scale longitudinal transfer matrix calculation, above threshold. This has the benefit of considering both the detailed bi-dimensional carrier behaviour at the Bragg-wavelength scale and the larger scale DFB effects such as the longitudinal spatial hole burning and the non-uniform current injection along the the laser cavity.

Analysis of an InGaAsP/InP twin-overlayed-waveguide switch

This paper examines the design considerations for a device combining vertical stacking of waveguides, carrier injection, and codirectional switching in InGaAsP/InP materials and demonstrates that many favorable features can be found in such a device, namely, an interaction length of about 408 /spl mu/m, switching with about 1 V with an injection current density of the order of 108-988 A/cm/sup 2/ and a channel isolation up to 25 db with an absorption loss of under 1 dB. We base our argument on a self-consistent numerical calculation. >