Low-Threshold Optical Bistability in Detuned DBR Heterostructures Integrated with Dirac Semimetals.

Optical bistability plays a vital role in high-performance all-optical devices. In this work, we construct a heterostructure consisting of distributed Bragg reflectors (DBRs) and three-dimensional Dirac semimetal (3D DSM), where a 3D DSM layer is sandwiched between two DBRs with mismatched central resonant wavelengths to realize effective excitation and coupling of optical Tamm states (OTSs). Benefiting from the strong optical field confinement and intrinsic Kerr nonlinearity of 3D DSM, the proposed structure achieves a low bistability threshold of 105 V/m. Moreover, the bistability performance can be tuned by modifying the Fermi level of 3D DSM and adjusting the incident angle. The proposed structure offers a promising theoretical platform for the future development of low-power terahertz bistable devices.