Ultra-broadband nanophotonic phase shifter based on subwavelength metamaterial waveguides

9 pags., 7 figs., 1 tab.Optical phase shifters are extensively used in integrated optics not only fortelecom and datacom applications but also for sensors and quantum computing. While various active solutions have been demonstrated, progress in passive phase shifters is still lacking. Here we present a new type of ultra-broadband 90° phase shifter, which exploits the anisotropy and dispersion engineering in subwavelength metamaterial waveguides. Our Floquet– Bloch calculations predict a phase-shift error below 1.7° over an unprecedented operation range from 1.35 to 1.75 μm, i.e., 400 nm bandwidth covering the E, S, C, L, and U telecommunication bands. The flat spectral response of our phase shifter is maintained even in the presence of fabrication errors up to 20 nm, showing greater robustness than conventional structures. Our device was experimentally demonstrated using standard 220 nm thick SOI wafers, showing a fourfold reduction in the phase variation compared to conventional phase shifters within the 145 nm wavelength range of our measurement setup. The proposed subwavelength engineered phaseshifterpaves thewayfornovel photonic integrated circuits withanultra-broadband performance. ©2020 Chinese Laser PressSpanish Ministry of Science, Innovation and Universities (MICINN) (IJCI-2016-30484, RTI2018-097957B-C33, TEC2015-71127-C2-1-R with FPI Scholarship BES2016-077798, TEC2016-80718-R, Alcyon Photonics S.L. Through CDTI SNEO-20181232); Spanish Ministry of Education, Culture and Sport (MECD) (FPU16/06762); Community of Madrid - FEDER Funds (S2018/NMT-4326); Horizon 2020 Research and Innovation Program (Marie Sklodowska-Curie 734331).Peer reviewe