Bound states in the continuum(BICs)are notable in photonics for their infinite Q factors.Perturbed BICs,or quasi-BICs(QBICs),have finite but ultra-high Q factors,enabling external coupling.So far,most studies have foc...Bound states in the continuum(BICs)are notable in photonics for their infinite Q factors.Perturbed BICs,or quasi-BICs(QBICs),have finite but ultra-high Q factors,enabling external coupling.So far,most studies have focused on the momentum-space properties of BICs and QBICs,with few discussions on their properties in real space.Here,we experimentally demonstrate that QBICs can induce abrupt lateral beam shifts.By applying Brillouin zone folding to a compound grating waveguide,we form a QBIC band where all states become QBICs.When excited at specific incident angles,these QBICs produce sudden lateral beam shifts,rapidly disappearing as frequencies deviate from the QBIC band.Using terahertz imaging,we capture these beam shifts at different incident angles,characterizing the QBIC band.This work offers alternative insights into QBIC behaviors and supports the development of advanced sensors and wavelength division(de)multiplexers.展开更多
Dielectric metasurfaces have achieved great success in realizing high-efficiency wavefront control in the optical and infrared ranges. Here, we experimentally demonstrate several efficient, polarization-independent, a...Dielectric metasurfaces have achieved great success in realizing high-efficiency wavefront control in the optical and infrared ranges. Here, we experimentally demonstrate several efficient, polarization-independent, all-silicon dielectric metasurfaces in the terahertz regime. The metasurfaces are composed of cylindrical silicon pillars on a silicon substrate, which can be easily fabricated using etching technology for semiconductors. By locally tailoring the diameter of the pillars, full control over abrupt phase changes can be achieved. To show the controlling ability of the metasurfaces, an anomalous deflector, three Bessel beam generators, and three vortex beam generators are fabricated and characterized. We also show that the proposed metasurfaces can be easily combined to form composite devices with extended functionalities. The proposed controlling method has promising applications in developing low-loss, ultra-compact spatial terahertz modulation devices.展开更多
基金supported by the Singapore National Research Foundation Competitive Research Program(NRF-CRP23-2019-0007)the Singapore Ministry of Education Academic Research Fund Tier 2(MOE-T2EP50123-0007)+1 种基金Feng Wu acknowledges support from the National Natural Science Foundation of China(12104105)Guangdong Basic and Applied Basic Research Foundation(2023A1515011024).
文摘Bound states in the continuum(BICs)are notable in photonics for their infinite Q factors.Perturbed BICs,or quasi-BICs(QBICs),have finite but ultra-high Q factors,enabling external coupling.So far,most studies have focused on the momentum-space properties of BICs and QBICs,with few discussions on their properties in real space.Here,we experimentally demonstrate that QBICs can induce abrupt lateral beam shifts.By applying Brillouin zone folding to a compound grating waveguide,we form a QBIC band where all states become QBICs.When excited at specific incident angles,these QBICs produce sudden lateral beam shifts,rapidly disappearing as frequencies deviate from the QBIC band.Using terahertz imaging,we capture these beam shifts at different incident angles,characterizing the QBIC band.This work offers alternative insights into QBIC behaviors and supports the development of advanced sensors and wavelength division(de)multiplexers.
基金National Basic Research Program of China(2014CB339800)National Natural Science Foundation of China(NSFC)(61420106006,61422509,61605143,61622505,61675145,61735012)+2 种基金Program for Changjiang Scholars and Innovative Research Team in University(IRT13033)Major National Development Project of Scientific Instruments and Equipment(2011YQ150021)Guangxi Key Laboratory of Automatic Detecting Technology and Instruments(YQ17203)
文摘Dielectric metasurfaces have achieved great success in realizing high-efficiency wavefront control in the optical and infrared ranges. Here, we experimentally demonstrate several efficient, polarization-independent, all-silicon dielectric metasurfaces in the terahertz regime. The metasurfaces are composed of cylindrical silicon pillars on a silicon substrate, which can be easily fabricated using etching technology for semiconductors. By locally tailoring the diameter of the pillars, full control over abrupt phase changes can be achieved. To show the controlling ability of the metasurfaces, an anomalous deflector, three Bessel beam generators, and three vortex beam generators are fabricated and characterized. We also show that the proposed metasurfaces can be easily combined to form composite devices with extended functionalities. The proposed controlling method has promising applications in developing low-loss, ultra-compact spatial terahertz modulation devices.
