A novel approach to finite-aperture tapered unstable resonator lasers

A novel concept of a Finite Aperture Tapered Unstable Resonator Laser (FATURL), based on two distributed Bragg reflectors (DBRs) at the rear and front facets with different lateral widths, is presented. The passive resonator analysis using Fresnel-Kirchhoff diffraction theory shows that with the grating widths the losses of the different lateral resonator modes change differently. This leads to resonator geometries, characterized by nearly integral Fresnel-numbers with higher modal discrimination of the fundamental lateral mode. In spatial-temporal simulations of the active device the influence of carrier-photon interaction on that effect is studied showing that the inhomogeneous index change by spatial hole-burning in the carrier density may become dominant over the geometric modal discrimination. Both, the influence of the grating widths on the suppression of higher order modes as well as the influence of spatial hole-burning is found in the experimental characterization of a first generation of fabricated devices.