Mid-infrared characterization of solution-processed As₂S ₃ chalcogenide glass waveguides

An etch-free and cost-effective deposition and patterning method to fabricate mid-infrared chalcogenide glass waveguides for chemical sensing applications is introduced. AS₂S₃ raised strip optical waveguides are produced by casting a liquid solution of AS₂S ₃ glass in capillary channel molds formed by soft lithography. Mid-IR transmission is characterized by coupling the output of a quantum cascade (QC) laser (λ = 4.8 μm) into the 40 μm wide by 10 μm thick multi-mode waveguides. Loss as low as 4.5 dB/cm is achieved using suitable substrate materials and post-processing. Optical absorption and surface roughness measurements indicate that the solution-processed films are of sufficient quality for optical devices and are promising for further development of waveguide-based mid-IR elements.