Polarizing grating coupler for high Q laser cavities

A coupling grating made in the last high-index layer of a highly reflective multilayer laser output mirror, located at the outside of the laser cavity, induces a significant fall of the reflection coefficient for one of the polarizations. The lasing polarization does not suffer more than 0.1% scattering. The understanding of device operation revealed by experiments shows the way for achieving an industrial manufacturing scheme, despite the poor control which layer-deposition technologies presently have on the layer index and thickness separately.