The mid-infrared band offers potential, attractive applications in the fields of free-space communications and sensing. In this PhD thesis, novel waveguide platforms based on Group IV semiconductors have been proposed to operate in the mid-infrared wavelength range. Specifically, suspended silicon and suspended germanium integrated structures with subwavelength lateral cladding — namely, waveguides, bends, and beamsplitters — have been experimentally demonstrated. Additionally, fiber-chip surface couplers with high efficiency and broad bandwidth have been designed.