Photonic crystal nanomaterials with arsenic sulphide chalcogenide and silicon for optical telecommunications

Photonic crystals or photonic band gap materials are materials with modulated refraction index in the wavelength range. In the optical domain, the index modulation must be in the micrometric or sub micrometric range. The structures that we had fabricated are constituted by nanometric cylindrical air holes in thin films of arsenic sulphide chalcogenide (As₂S₃) and silicon. We obtained these two-dimensional structures by a holographic technique that we developed in two steps using an argon ion laser. We also fabricated waveguides, couplers, or Y junctions incorporated into a two-dimensional photonic crystal by combining the techniques of photolithography and holography. The functionality of these optical devices was also demonstrated at the wavelength of 1.55 mum. We also simulated the optical properties of these materials in order to understand how a homogenate medium can be profoundly modified when we structure periodically refraction index in the range of the wavelengths crossing it. Band diagrams were calculated for different structures, materials, refractive indices, dimensions, and polarizations. The method of Finite Difference Time Domain (FDTD) was also used to simulate the behavior of the 90deg waveguides, couplers, Y junctions, and a Mach-Zehnder interferometer incorporated into a two-dimensional structure of cylindrical air holes of AS₂S₃ or silicon. We particularly demonstrated the functionality of these optical components when operating at telecommunication wavelength at 1.55 mum.