Demonstration and characterization of ultrafast laser-inscribed mid-infrared waveguides in chalcogenide glass IG2

The first demonstration and characterization of ultrafast laser-inscribed mid-infrared (mid-IR) waveguides in Ge₃₃As₁₂Se₅₅ chalcogenide glass (IG2) is presented. From mode profile and throughput measurements, combined with modelling, the characteristics of the waveguides inscribed in IG2 are studied at 7.8 μm, and compared to those of waveguides inscribed in gallium lanthanum sulfide for reference. Two methods to estimate the local variation of refractive index induced by the inscription process are presented, which indicate a variation of ~0.010 to 0.015 across the inscription parameters investigated. This variation, together with a higher robustness of the material to inscription and large transparency covering the entire mid-IR spectral domain, suggest that IG2 has great potential for integrated optical applications in the mid-IR developed through the ultrafast laser inscription method.