摘要
In silicon photonics,the cavity mode is a fundamental mechanism to design integrated passive devices for on-chip optical information processing.Recently,the corner state in a second-order topological photonic crystal(PC)rendered a global method to achieve an intrinsic cavity mode.It is crucial to explore such a topological corner state in silicon photonic integrated circuits(PICs)under in-plane excitation.Here,we study both theoretically and experimentally the topological nanophotonic corner state in a silicon-on-insulator PC cavity at a telecommunications wavelength.In theory,the expectation values of a mirror-flip operation for the Bloch modes of a PC slab are used to characterize the topological phase.Derived from topologically distinct bulk polarizations of two types of dielectric-vein PCs,the corner state is induced in a 90-deg-bend interface,localizing at the corner point of real space and the Brillouin zone boundary of reciprocal space.To implement in-plane excitation in an experiment,we fabricate a cross-coupled PC cavity based on the bend interface and directly image the corner state near 1383 nm using a far-field microscope.Finally,by means of the temporal coupled-mode theory,the intrinsic Q factor of a cross-coupled cavity(about 8000)is retrieved from the measured transmission spectra.This work gives deterministic guidance and potential applications for cavity-mode-based passive devices in silicon PICs,such as optical filters,routers,and multiplexers.
基金
National Key Research and Development Program of China(2019YFB2203502)
National Natural Science Foundation of China(62035016,11904421,61775243,11761161002,12074443)
Natural Science Foundation of Guangdong Province(2018B030308005,2018A030310089)
Guangdong Basic and Applied Basic Research Foundation(2019B151502036)
Guangzhou Science and Technology Program key projects(201804020029)
Guangzhou Science and Technology and Innovation Commission(202002030322)
China Postdoctoral Science Foundation(2018M633206)。
