a) Material and devices.

1: - Standard VCSELs, optimisation.
Production of low noise, high efficiency and narrow linewidth samples, in the wavelength range 750-980nm using standard and advanced technologies. (EPFL, UNI_ULM, CNET).
Optimisation of the laser geometry according to the results of the characterisation (see research areas b and c). (EPFL, CNET, UNI_ULM, UCC+ Bristol, KTH).

2: - Novel VCSELs.
Study of novel III-V materials, including GaInSbAs/GaAs as a substitute for the conventional InGaAsP/InP where VCSELs are difficult to grow. (UNI_ULM).
Growth of quantum wire and quantum dot structures for improved gain characteristics. Production of devices based on quantum dots at 1.3mm. (EPFL).

b) Nonlinear effects.

1: - Standard VCSELs, free running.
Characterisation of intensity noise in connection with mode anticorrelation (UPMC_LKB, INFM_FI); comparison of correlation values with models predictions, study of the relation with geometric parameters.
Experimental investigation of the generation of polarisation oscillations in optically pumped VCSELs. (CNET).

2: - Standard VCSELs, feedback regime.
Experimental investigation of the dynamical polarisation correlation in regimes of strong feedback. ( IMEDEA+ INLN, INFM_FI, UCC).
Comparison with models and with numerical simulations (see research area d).

3: - VCSEL arrays and broad area.
Theoretical and experimental study of VCSEL arrays: polarisation properties of two coupled VCSELs ( IMEDEA+ INLN); experimental study of synchronisation effects in the polarisation dynamics. ( INFM_FI).
Theoretical and experimental study of broad area VCSELs: localised structures and their control by selective feedback and injection; pattern dynamics. ( IMEDEA, UCC, INFM_MI).

4: - Towards new lasers.
Experimental characterisation of intensity and polarisation noise, spatially distributed noise, polarisation and transverse modes dynamics of VCSELs, extended to new kind of lasers (1.3mm, quantum wires and quantum dots, new materials). ( INFM_FI, IMEDEA+ INLN, UPMC_LKB, CNET).

c) Quantum effects.

1: - Quantum intensity noise.
Intensity noise measurements on VCSELs coming from different available sources in the network (see research area a). (UPMC_LKB, CNET). Taking advantage from the theoretical models (see research area d), identification of the most favourable design.
In the case of single mode VCSEL, comparison of the noise performance with a single mode microscopic theory. (UPMC_LKB, INFM_MI). Search for optimum quantum noise reduction in multimode VCSELs by using injection locking; comparison with theory. (UPMC_LKB).

2: - Quantum correlations.
Measurement of anticorrelation between modes in high-noise and low-noise VCSELs (UPMC_LKB+IOTA, INFM_FI). Comparison with quantum multimode model. (the same groups, with IMEDEA and INFM_MI).

3: - Analysis of spontaneous emission modification in metallic VCSELs. (CNET).

d) Basic modelling and numerical simulations.

1: - Basic modelling.
Useful semiconductor susceptibility modelling at a mesoscopic level incorporating important microscopic/many body effects and thermal effects. Implementation of such models for transverse profile properties of broad area VCSELs. Consequences on modulation properties. ( IMEDEA+Santander).
Modelling and experimental proposals to characterise spin coherence properties and their relevance for polarisation properties. ( IMEDEA).
Investigation of the physical mechanisms (such as the electro-optical effect, strain) responsible for linear and non-linear anisotropies. (INFM_MI).

2: - Noise and small modulation response.
Analytical calculation of Relative Intensity Noise spectra and small signal modulation response taking into account the spatial dependence of electromagnetic field, carriers and spontaneous emission noise. This analysis is extended to the case of an arbitrary number of transverse modes. ( IMEDEA+Santander, INFM_MI).
Quantum noise model in the presence of two polarisation modes and/or two transverse modes, in the presence of carrier diffusion. (INFM_MI).

3: - Polarisation and trasverse modes dynamics.
Development of numerical codes for the study of the stability and of the dynamical behaviour of transverse modes, including large current modulation and optical feedback from an external cavity. (INFM_MI, IMEDEA+Santander).
Theoretical investigation of the generation of polarisation oscillations in optically pumped VCSELs. ( IMEDEA).

4: - Spatial structures.
Analysis of the transverse modes of VCSELs including the effect of gain guiding and of oxide layer for carrier confinement with different transverse geometry: electromagnetic field distributions, threshold conditions, polarisation selection, spectral linewidth. (INFM_MI, UCC+ Bristol).
Theoretical study of cooperative phenomena, spontaneous or induced by an injected field. ( IMEDEA, INFM_MI).
Analysis of the phase-locked states in arrays with different geometries (rectangular, triangular) with evanescent coupling and investigation of the possible effects due to coupling through carrier diffusion. (INFM_MI).
Improved models for cavity solitons: integrated modelling of free carrier and excitonic nonlinearities; analysis of thermal effects in regimes of carrier photogeneration, possible extension of the models beyond the paraxial approximation, study of semiclassical correlations in dynamical patterns. (INFM_MI).

e) Systems.

1: - Intensity switching.
Theoretical analysis of timing jitter and transient mode partition noise, by means of analytical calculations and numerical simulations. The effects of mode partition noise in fibre data links is analysed. (KTH, IMEDEA+Santander).
Modelization, characterisation and integration of (850nm and red) VCSELs in data communication systems. (KTH, UCC, INFM_FI+VUB).
Measurement of time-response and switching characteristics of VCSELs based on new materials and on quantum wire and quantum dot structures. (EPFL).

2: - Polarisation and mode switching.
Measurement of the laser response to current modulation in conditions of polarisation and pattern bistability and multistability. ( INFM_FI+VUB). Investigation of the effects of an opto-electronic feedback on the laser stability, in particular concerning intensity switchings and modulation. ( INFM_FI).
Control of VCSEL polarisation and spatial mode by innovative cavity geometries. ( UCC+ Bristol).