Sánchez-Postigo, AlejandroOrtega-Moñux, AlejandroSoler Penadés, JordiOsman, AhmedNedeljkovic, MilosQu, ZhiboWu, YangboMolina-Fernández, ÍñigoCheben, PavelMashanovich, Goran ZWangüemert-Pérez, J Gonzalo2023-02-092023-02-092021http://hdl.handle.net/10668/18030In recent years, sensing and communication applications have fueled important developments of group-IV photonics in the mid-infrared band. In the long-wave range, most platforms are based on germanium, which is transparent up to ∼15-µm wavelength. However, those platforms are limited by the intrinsic losses of complementary materials or require complex fabrication processes. To overcome these limitations, we propose suspended germanium waveguides with a subwavelength metamaterial lateral cladding that simultaneously provides optical confinement and allows structural suspension. These all-germanium waveguides can be fabricated in one dry and one wet etch step. A propagation loss of 5.3 dB/cm is measured at a wavelength of 7.7 µm. These results open the door for the development of integrated devices that can be fabricated in a simple manner and can potentially cover the mid-infrared band up to ∼15 µm.enAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/research article34154239open access10.1364/OE.4227641094-4087https://doi.org/10.1364/oe.422764