Laser Emission Control by Means of Resonant Gratings

New diffractive optical elements of the resonant type result from the association of a surface corrugation with an optical resonator in the form of a slab waveguide whose surface is corrugated or whose refractive index is periodically modulated. As a result, the resonant corrugation diffracts an incident free space wave more efficiently than a conventional corrugation and, more importantly, exhibits selectivity features in angle, wavelength and polarization which can be used for the control of laser emission. A practically attractive characteristic of such elements is that they are planar, therefore they can be associated monolithically with the laser mirror, and can be fabricated by low‐cost and highly reproducible batch planar microstructuring technologies. The characteristics of laser emission which can be controlled are the emission wavelength(s), the polarization and the polarization distribution over the beam cross‐section, and even the transverse mode content (i.e., the spatial coherence of the emi...