Active Control of Nanodielectric‐Induced THz Quasi‐BIC in Flexible Metasurfaces: A Platform for Modulation and Sensing

• DOI: 10.1002/adma.202100836
• Publication Date: 2021-05-29T12:06:49Z
• Authors: Thomas CaiWei Tan; Yogesh Kumar Sriv...; Rajour Tanyi Ako; Wenhao Wang; Madhu Bhaskaran; Sharath Sriram; Ibraheem Al‐Naib; Eric Plum; Ranjan Singh
• Keywords: Photoexcitation; Nanophotonics; Fano resonance; Modulation (music)

Abstract A bound state in the continuum (BIC) is a nonradiating of light embedded propagating modes providing drastic enhancement electromagnetic field and its localization at micro–nanoscale. However, access to such far‐field requires symmetry breaking. Here, it demonstrated that nanometric dielectric or semiconductor layer, 1000 times thinner than resonant wavelength (λ/1000), induces dynamically controllable quasi‐bound (QBIC) with ultrahigh quality factor symmetric metallic metasurface terahertz frequencies. Photoexcitation nanostrips germanium activates ultrafast switching QBIC resonance 200% transmission intensity modulation complete recovery within 7 ps on low‐loss flexible substrate. The also form microchannels provide an opportunity for BIC‐based refractive index sensing. An optimization model presented (switchable) resonances metamaterial arrays planar resonators modified any (active) inverse design can serve as enabling platform active micro–nanophotonic devices.