Single-scan ultrafast laser inscription of waveguides in IG2 for type-I and type-II operation in the mid-infrared.

We demonstrate, for the first time to our knowledge, single-scan ultrafast laser inscription and performance of mid-infrared waveguiding in IG2 chalcogenide glass in the type-I and type-II configurations. The waveguiding properties at 4550 nm are studied as a function of pulse energy, repetition rate, and additionally separation between the two inscribed tracks for type-II waveguides. Propagation losses of ∼1.2 dB/cm in a type-II waveguide and ∼2.1 dB/cm in a type-I waveguide have been demonstrated. For the latter type, there is an inverse relation between the refractive index contrast and the deposited surface energy density. Notably, type-I and type-II waveguiding have been observed at 4550 nm within and between the tracks of two-track structures. In addition, although type-II waveguiding has been observed in the near infrared (1064 nm) and mid infrared (4550 nm) in two-track structures, type-I waveguiding within each track has only been observed in the mid infrared.