High-finesse Fabry-Perot cavities with bidimensional Si3N4 photonic-crystal slabs

A team in France has made a high-reflective photonic crystal on a Si3N4 nanomembrane that exploits an optical effect known as Fano resonance. Two-dimensional photonic-crystal slabs containing subwavelength periodic structures are promising for making various optical components for nanophotonics applications. Now, Thibaut Jacqmin and Samuel Deleglise of Kastler Brossel Laboratory in Paris and co-workers have fabricated such a photonic-crystal slab directly into a Si3N4 nanomembrane. Its reflectivity can be tuned over a wide range — from almost 0% to 99.947% — by adjusting the laser wavelength close to the Fano resonance. Higher reflectivities may be achievable as absorption by the material is not the main source of light loss. The researchers provide a theoretical analysis of the optical properties of their slab, which could be used for tunable optical filters and optomechanical lasers.