We demonstrate a tunable terahertz(THz) absorber based on an indium tin oxide(ITO) metamaterial. The upper ITO cross-shaped metasurface with different arm lengths is fabricated by direct femtosecond laser etching.The ...We demonstrate a tunable terahertz(THz) absorber based on an indium tin oxide(ITO) metamaterial. The upper ITO cross-shaped metasurface with different arm lengths is fabricated by direct femtosecond laser etching.The thickness of the middle dielectric layer is only 60 μm, which makes the absorber very transparent and flexible. The experimental results show that the THz resonant peaks have a high performance near 1 THz. By setting spacers of different thicknesses between the middle layer and the ITO mirror, a new type of tunable THz absorber is proposed. Its absorption peak frequency can be continuously adjusted from 0.92 to 1.04 THz between TE and TM polarization. This transparent THz metamaterial absorber is expected to be widely used in THz imaging, sensing, and biological detection.展开更多
Spatial terahertz wave modulators that can arbitrarily tailor the electromagnetic wavefront are in high demand in nondestructive inspections and high-capacity wireless communications.Here,we propose a liquid crystal i...Spatial terahertz wave modulators that can arbitrarily tailor the electromagnetic wavefront are in high demand in nondestructive inspections and high-capacity wireless communications.Here,we propose a liquid crystal integrated metadevice.It modulates the terahertz wave based on the adjustable electromagnetically induced transparency analog when spatially changing the environmental refractive index.The functions of the device can be arbitrarily programmed via photo-reorienting the directors of liquid crystals with a digital micromirror device-based exposing system.The thin liquid crystal layer can be further driven by an electric field,and thus the function can be rapidly switched.Amplitude modulation and the lens effect are demonstrated with modulation depths over 50%at 0.94 THz.展开更多
In this Letter, we propose that the photopatterned liquid crystal(LC) can act as a broadband and efficient terahertz(THz) Bessel vortex beam(BVB) generator. The mechanism lies in the frequency-independent geometric ph...In this Letter, we propose that the photopatterned liquid crystal(LC) can act as a broadband and efficient terahertz(THz) Bessel vortex beam(BVB) generator. The mechanism lies in the frequency-independent geometric phase modulation induced by the spatially variant LC directors. By adopting large birefringence LCs and optimizing the cell gap, the maximized mode conversion efficiency can be continuously adjusted in broadband.Furthermore, the LC patterns can be designed and fabricated at will, which enables the THz BVBs to carry various topological charges. Such a THz LC BVB generator may facilitate the advanced THz imaging and communication apparatus.展开更多
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China(No. 61605088)the Openof the National Laboratory of Solid State Microstructures,China+1 种基金the Fundamental Research Funds for the Central Universities (No. 021314380095)the China Postdoctoral Science Foundation (No. 2019M651768)。
文摘We demonstrate a tunable terahertz(THz) absorber based on an indium tin oxide(ITO) metamaterial. The upper ITO cross-shaped metasurface with different arm lengths is fabricated by direct femtosecond laser etching.The thickness of the middle dielectric layer is only 60 μm, which makes the absorber very transparent and flexible. The experimental results show that the THz resonant peaks have a high performance near 1 THz. By setting spacers of different thicknesses between the middle layer and the ITO mirror, a new type of tunable THz absorber is proposed. Its absorption peak frequency can be continuously adjusted from 0.92 to 1.04 THz between TE and TM polarization. This transparent THz metamaterial absorber is expected to be widely used in THz imaging, sensing, and biological detection.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.62035008,62105143,and 61922038)the Natural Science Foundation of Jiangsu Province(No.BK20210179)the Fundamental Research Funds for the Central Universities(No.021314380189).
文摘Spatial terahertz wave modulators that can arbitrarily tailor the electromagnetic wavefront are in high demand in nondestructive inspections and high-capacity wireless communications.Here,we propose a liquid crystal integrated metadevice.It modulates the terahertz wave based on the adjustable electromagnetically induced transparency analog when spatially changing the environmental refractive index.The functions of the device can be arbitrarily programmed via photo-reorienting the directors of liquid crystals with a digital micromirror device-based exposing system.The thin liquid crystal layer can be further driven by an electric field,and thus the function can be rapidly switched.Amplitude modulation and the lens effect are demonstrated with modulation depths over 50%at 0.94 THz.
基金supported by the National Natural Science Foundation of China (NSFC)(No. 61922038)the Fundamental Research Funds for the Central Universities (No. 14380170)。
文摘In this Letter, we propose that the photopatterned liquid crystal(LC) can act as a broadband and efficient terahertz(THz) Bessel vortex beam(BVB) generator. The mechanism lies in the frequency-independent geometric phase modulation induced by the spatially variant LC directors. By adopting large birefringence LCs and optimizing the cell gap, the maximized mode conversion efficiency can be continuously adjusted in broadband.Furthermore, the LC patterns can be designed and fabricated at will, which enables the THz BVBs to carry various topological charges. Such a THz LC BVB generator may facilitate the advanced THz imaging and communication apparatus.
