(a) SEM micrograph of a multilayer As₂₄S₃₈Se₃₈/As₂S₃ rid waveguide processed by lithography and wet etching (Viens et al.).^[9] (b) Cross-sectional image of Ge₂₃Sb₇S₇₀ waveguide patterned by SF⁶ plasma etching (Hu et al.).^[11] (c) SEM micrograph showing the profile of As₂S₃ waveguide etched by ICP and coated with polysiloxane cladding (Ruan et al.).^[12] (d) Optical micrograph of cleaved finished waveguide in the 2.6-µm thick As₂S₃ film (Madden et al.).^[13]