Benedikovic, DanielAlonso-Ramos, CarlosCheben, PavelSchmid, Jens HWang, ShuruiHalir, RobertOrtega-Moñux, AlejandroXu, Dan-XiaVivien, LaurentLapointe, JeanJanz, SiegfriedDado, Milan2025-01-072025-01-072016https://hdl.handle.net/10668/25285We report, for the first time, on the design and experimental demonstration of fiber-chip surface grating couplers based on subwavelength grating engineered nanostructure operating in the low fiber chromatic dispersion window (around 1.3 μm wavelengths), which is of great interest for short-reach data communication applications. Our coupler designs meet the minimum feature size requirements of large-volume deep-ultraviolet stepper lithography processes. The fiber-chip couplers are implemented in a standard 220-nm-thick silicon-on-insulator (SOI) platform and are fabricated by using a single etch process. Several types of couplers are presented, specifically the uniform, the apodized, and the focusing designs. The measured peak coupling efficiency is -2.5 dB (56%) near the central wavelength of 1.3 μm. In addition, by utilizing the technique of the backside substrate metallization underneath the grating couplers, the coupling efficiency of up to -0.5 dB (89%) is predicted by Finite Difference Time Domain (FDTD) calculations.enAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/research article27410309open access10.1364/OE.24.0128931094-4087https://doi.org/10.1364/oe.24.012893