Transverse Fourier mode selection in VCSELs due to DBR reflectors

Summary form only given. Design of broad-area VCSELs has opened possibilities to observe in lasers spatially periodic structures corresponding to tilted waves. Theoretical models used to describe lasers with a large Fresnel number are usually based on amplitude equations derived from the Maxwell-Bloch equations for a two-level system. Treating the polarization of an active medium accounts for gain dispersion which provides an important means for mode selection. Near the lasing threshold the detuning between the cavity frequency and the peak gain frequency determines characteristics of the output field. However, there are some distinctions between experimental data and theoretical predictions. They can be caused by both a weakness of the dispersion mode-selection mechanism because of too short polarization relaxation time in semiconductors and an existence of another mechanism of Fourier mode selection in VCSELs. In the report we show that a dependence of reflection from a DBR structures on an incident angle of tilted waves leads also to the mode selection. The efficiency of this mechanism is determined by a phase mistuning in the lower and upper parts of the cavity.