Penades, J SolerOrtega-Moñux, ANedeljkovic, MWangüemert-Pérez, J GHalir, RKhokhar, A ZAlonso-Ramos, CQu, ZMolina-Fernández, ICheben, PMashanovich, G Z2025-01-072025-01-072016https://hdl.handle.net/10668/25286We present several fundamental photonic building blocks based on suspended silicon waveguides supported by a lateral cladding comprising subwavelength grating metamaterial. We discuss the design, fabrication, and characterization of waveguide bends, multimode interference devices and Mach-Zehnder interferometers for the 3715 - 3800 nm wavelength range, demonstrated for the first time in this platform. The waveguide propagation loss of 0.82 dB/cm is reported, some of the lowest loss yet achieved in silicon waveguides for this wavelength range. These results establish a direct path to ultimately extending the operational wavelength range of silicon wire waveguides to the entire transparency window of silicon.enAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/research article27828358open access10.1364/OE.24.0229081094-4087https://doi.org/10.1364/oe.24.022908