Suspended germanium waveguides with subwavelength-grating metamaterial cladding for the mid-infrared band

In recent years, sensing and communication applications have fueled important developments of group-IV photonics in the mid-infrared band. long-wave range, most platforms are based on germanium, which is transparent up to ∼15-µm wavelength. However, those limited by intrinsic losses 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 allows structural suspension. These all-germanium can be fabricated one dry wet etch step. A propagation loss 5.3 dB/cm measured at wavelength 7.7 µm. results open door for development integrated devices simple manner potentially cover band ∼15