We present the development of SOI waveguides with low-loss (~1.5 dB/cm) single-moded guidance over an octave of frequency. Broadband single-moded guidance is needed for on-chip mid-infrared spectroscopy and this cannot be provided by conventional waveguide geometries in standard material platforms. The reported waveguides require a simple fabrication process flow and will be widely applicable to different mid-infrared wavelength bands for a variety of sensing applications. We further present a low-loss bend design (0.179 ± 0.031 dB/90°) that overcomes the inherently large bending loss of the waveguides, which is a limiting factor in the utility of the waveguides. We consider different prospective designs for the use of these waveguides in a circuit for a sensing device.

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Callum J. Stirling, April Logan, Wei Cao, Jamie D. Reynolds, Zhibo Qu, Thomas D. Bradley, Lorenzo Mastronardi, Frederic Y. Gardes, Goran Z. Mashanovich, and Milos Nedeljkovic, "Mid-infrared waveguides for broadband single-moded guidance," Proc. SPIE 12575, Integrated Optics: Design, Devices, Systems and Applications VII, 1257503 (Presented at SPIE Optics + Optoelectronics: April 24, 2023; Published: 31 May 2023); https://doi.org/10.1117/12.2665590.