A tunable silicon-on-insulator valley Hall photonic crystal at telecommunication wavelengths

作者：Dong, ZhaoHui; Xu, Feng; Liang, Wenyao^*

来源：Europhysics Letters, 2020, 131(5): 54002.

DOI：10.1209/0295-5075/131/54002

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Silicon-on-insulator (SOI) combined with topological photonics provides on-chip integrated photonic devices CMOS-compatibility and backscattering-suppression. Here we propose a tunable SOI-based valley Hall topological insulator with two nonequivalent air holes to break inversion symmetry. Due to free-carrier excitation, the real and imaginary parts of the refractive index are modified to cause a blue-shift of bandgap and a reduction of transmittance, respectively. Based on this mechanism, we design a tunable all-optical switch with the merits of high transmittance contrast (about 23) and polarization-resolved characteristics simultaneously. Our proposed approach has potential in broadband tunable integrated photonic devices at telecommunication wavelengths.