Towards low-loss mid-infrared waveguides in Ge-on-SOI

Mid-infrared waveguides of different Ge core thicknesses have been developed in Ge-on-SOI. Minimum propagation loss of ∼8 dB/cm has been achieved for 0.85 μm thick Ge core using 3.682 μm laser excitation. The waveguides are transparent up to at least 3.82 μm.