Showing papers by "Jianquan Yao published in 2021"
TL;DR: In this paper, a metamaterial-based biosensor was proposed to realize polarization-independent electromagnetic induced transparency (EIT) at THz frequencies for molecular classification of glioma cells.
78 citations
TL;DR: In this article, a reflective chiral THz metasurface that reflection medium in bottom is based on monolayer graphene on low resistance Si substrate is designed to control the chiral properties of metasuface by a simple and effective method.
68 citations
TL;DR: The findings demonstrate that the novel THz biosensor offers the capability for highly sensitive miRNA detection, with noteworthy potential applications in nucleic acid analysis and cancer diagnosis.
60 citations
TL;DR: In this article, the free switch between BIC and quasi-BIC is successfully achieved by introducing the structured graphene into the metal terahertz metasurfaces, which is based on free-electron concentration of graphene changing from semiconductor-like to metal-like with adjustment of Fermi energy.
59 citations
TL;DR: In this paper, an ultra-wide detection range refractive index sensor based on surface plasmon resonance (SPR) with photonic crystal fiber (PCF) is designed and discussed.
Abstract: An ultra-wide detection range refractive-index sensor based on surface plasmon resonance (SPR) with photonic crystal fiber (PCF) is designed and discussed. The central air-hole of the fiber is injected with the analyte. The properties of refractive-index sensor are investigated with different structure parameters. Simulation results show that the proposed sensor has an ultra-wide detection range from 1.29 to 1.49. The refractive index sensitivities of x-polarized and y-polarized core mode are −4156.82 nm/RIU and −3703.64 nm/RIU respectively, and the corresponding linear fitting degrees are 0.99598 and 0.99236. The designed refractive-index sensor with ultra-wide detection range has a great potential in the fields of biology, chemistry, environment and medicine.
55 citations
36 citations
35 citations
TL;DR: In this paper, a spin-selective asymmetric transmission in terahertz band based on the all-silicon metasurface has been explored, and the maximum circular dichroism can reach 0.4.
Abstract: A strong spin-selective asymmetric transmission metasurface usually relies on a multilayer metal frame or compound all-dielectric system. By contrast, an all-silicon metasurface has advantages of simple process, low cost, and easy optical modulation. However, there is little work to explore the spin-selective asymmetric transmission in terahertz band based on the all-silicon metasurface due to weak interaction between all-silicon materials and terahertz waves. Herein, we have achieved excellent spin-selective terahertz asymmetric transmission in the all-silicon metasurface by the ingenious chirality structure design, and the maximum circular dichroism can reach 0.4. Meanwhile, 1064 nm continuous wave optical pumping modulates the asymmetric transmission amplitude of the all-silicon metasurface to achieve circular dichroism switch between “On” and “Off.” We have also developed terahertz chiral imaging applications based on the all-silicon metasurface with spin-selective asymmetric transmission, and the chiral imaging with On and Off switching characteristics can be realized via optically active control.
34 citations
TL;DR: In this article, a CsPbX3, X=Cl, Br, I) perovskite nanocrystals (NCs) have attracted increasingly research interest as highly efficient light absorbers in optoelectronic devices for their outstanding optical properties.
Abstract: All-inorganic cesium lead halide (CsPbX3, X=Cl, Br, I) perovskite nanocrystals (NCs) have attracted increasingly research interest as highly efficient light absorbers in optoelectronic devices for their outstanding optical properties. Here, a CsPbBr3 NCs/graphene hybrid photodetector was demonstrated for efficient ultraviolet light detection, in which CsPbBr3 NCs served as a light absorber, and graphene acted as a carrier transport expressway. The device exhibited high hole and electron mobilities of 1.7 × 103 cm2/V s and 6.4 × 103 cm2/V s in the dark. Under 405 nm illumination, the device showed high responsivity, specific detectivity, external quantum efficiency with maximum values of 3.4 A/W, 7.5 × 108 Jones, 103%, respectively, and short rise/decay times of 7.9/125 ms. The hybrid PD has important prospects in the photodetection applications of optical communication, biological imaging, remote sensing, and other multifunction optoelectronics.
29 citations
TL;DR: In this article, all-silicon chiral metasurfaces for highly efficient CPDT in the terahertz band were proposed, where the chiral optical response represents interactions of circularly polarized light with matter.
Abstract: The chiral optical response represents interactions of circularly polarized light with matter Chiral metamaterials are widely applied in polarization imaging, optical sensing, and other fields due to their strong ability to manipulate light and form giant circular polarization differential transmittance (CPDT) Here, we propose all-silicon chiral metasurfaces for highly efficient CPDT in the terahertz band In addition to characterizing the static chiral properties of our proposed metasurface, dynamic chiral behaviors are also characterized by optical pumping (1064 nm continuous wave), and a giant amplitude modulation depth is obtained The measured results agree well with the simulations In addition, the application of our chiral metasurface in polarization multiplexed near-field image display is also exhibited Such chiral metasurface could find many potential applications in photon-spin selective devices, such as circularly polarized light detectors and chiral sensors
26 citations
TL;DR: An efficient high-power single-frequency thulium-doped fiber ring laser operating at 1720 nm is demonstrated by incorporating a fiber Bragg grating and potential power scaling of the single- frequencies with different quantity and lengths of the sub-rings was theoretically investigated.
Abstract: Here we demonstrated an efficient high-power single-frequency thulium-doped fiber ring laser operating at 1720 nm. Three cascaded sub-rings were inserted into the main cavity to significantly enlarge the effective free spectral range. By incorporating a fiber Bragg grating, the single longitudinal mode operation was achieved. The maximum single-frequency output power reached up to 1.11 W under 3.75-W launched pump power, while the slope efficiency with respect to the absorbed pump power was 46.4%. The laser linewidth at maximum single-frequency power was measured of 1.9 kHz. Potential power scaling of the single-frequency output power with different quantity and lengths of the sub-rings was also theoretically investigated.
TL;DR: In this article, a single-frequency operation of a thulium-doped fiber laser at a short wavelength of 1720 nm is investigated in a ring resonator.
Abstract: The single-frequency operation of a thulium fiber laser at a short wavelength of 1720 nm is investigated in a ring resonator. Powerful single-longitudinal-mode operation was realized by utilizing an unpumped thulium-doped fiber as the saturable absorber. The fiber laser delivered 407 mW single-frequency output with a spectral linewidth of 4.4 kHz under 2.7-W launched pump power at 1570 nm, which turned to multi-longitudinal-mode operation at higher pump powers. Additionally, optical bistability of both output power and longitudinal mode behavior, originating from the saturable absorption effect, were observed and discussed. To the best of our knowledge, this is the first efficient 1.7-μm single-frequency fiber laser as well as the first demonstration of optical bistability in thulium-doped fiber lasers.
TL;DR: AlNb2TiV as discussed by the authors, a light-weight, refractory high-entropy alloy with high specific strength and excellent room-temperature deformability is identified.
TL;DR: In this paper, a surface plasmon resonance (SPR) sensor based on exposed core micro-structured optical fiber (EC-MOF) for temperature self-compensated salinity detection is proposed.
Abstract: A surface plasmon resonance (SPR) sensor based on exposed core micro-structured optical fiber (EC-MOF) for temperature self-compensated salinity detection is proposed. The sensing channel is fabricated by sequentially coating indium tin oxide (ITO) and Au layers at the exposed region of the fiber core. Benefiting from the large dynamic refractive index (RI) range of ITO induced by dispersion, two separated SPR peaks with equal intensity can be excited at visible spectrum by Kretschmann configuration and near-infrared spectrum by Otto configuration. The RI sensing performance at 1.33–1.39 is investigated and optimized using finite element method, with maximum wavelength sensitivities of 2000 nm/RIU and 3000 nm/RIU, respectively. The distinct RI responses of two SPR peaks make the dual-parameter demodulation realizable, which shows great potential in multiplex or self-compensated sensing applications. The temperature self-compensated salinity sensing ability is demonstrated with high sensitivity of 4.45 nm/% and a temperature compensation coefficient of −0.12%/°C. To the best of our knowledge, this is the first time temperature self-compensation of fiber SPR sensors with a single sensing channel and the single demodulation method has been realized.
TL;DR: In this article, an end-pumped Laguerre-Gaussian (LG) mode-selectable Nd:YVO4 laser utilizing enhanced intracavity spherical aberration was demonstrated.
Abstract: We demonstrate an end-pumped Laguerre-Gaussian (LG) mode-selectable Nd:YVO4 laser utilizing enhanced intracavity spherical aberration. The cavity was designed to exploit strong spherical aberration generated by an expanded beam, incident on a short-focal-length lens, which enabled oscillation of cavity modes of different order. This compact-cavity laser could operate efficiently with high-order LG mode, with the order of this mode being selectively changed by simply adjusting the distance between the short-focal-length lens and the output coupler. Scalar LG modes from LG0,±10 to up to LG0,±33 were observed in the experiment. The output power of the LG0, ±33 mode was 1.87 W under an absorbed pump power of 6.6 W.
TL;DR: In this paper, the linear shape birefringence effect in spatially interleaved anisotropic meta-atoms is exploited for terahertz wavefront shaping with multi-channel polarization conversion via all-silicon metasurface.
Abstract: Polarization manipulation of electromagnetic wave or polarization multiplexed beam shaping based on metasurfaces has been reported in various frequency bands. However, it is difficult to shape the beam with multi-channel polarization conversion in a single metasurface. Here, we propose a new method for terahertz wavefront shaping with multi-channel polarization conversion via all-silicon metasurface, which is based on the linear shape birefringence effect in spatially interleaved anisotropic meta-atoms. By superimposing the eigen- and non-eigen-polarization responses of the two kinds of meta-atoms, we demonstrate the possibility for high-efficiency evolution of several typical polarization states with two independent channels for linearly polarized waves. The measured polarization conversion efficiency is higher than 70% in the range of 0.9–1.3 THz, with a peak value of 89.2% at 1.1 THz. In addition, when more other polarization states are incident, combined with the integration of sub-arrays, we can get more channels for both polarization conversion and beam shaping. Simulated and experimental results verify the feasibility of this method. The proposed method provides a new idea for the design of terahertz multi-functional metadevices.
TL;DR: An efficient, long-distributed-cavity laser which uses a cat-eye retroreflector configuration to facilitate cavity alignment and the fluctuation in output power over the whole working distance range of 1-5 m was less than 10%, this being achieved without any other cavity parameters being adjusted.
Abstract: Here we demonstrate an efficient, long-distributed-cavity laser which uses a cat-eye retroreflector configuration to facilitate cavity alignment. The cavity parameters were optimized to meet the small stability region of the cavity, given the long working distance. We also found that intracavity spherical aberration seriously impacts laser efficiency, and an aspheric lens is used to correct the aberration when long working distance and receivers with compact dimensions are desired. The end-pumped Nd:YVO4 laser delivered 5.91 W continuous-wave output power at a long working distance of 5 m, under 16.6 W incident diode pump. Significantly, the fluctuation in output power over the whole working distance range of 1–5 m was less than 10%, this being achieved without any other cavity parameters being adjusted.
TL;DR: In this article, a laser pump with micropower densities and a mains with weak voltages were applied to the terahertz metasurface and observed the modulation behavior of higher-order Fano resonance at the Dirac point.
TL;DR: In this article, the authors used time-resolved optical pump-THz probe spectroscopy to explore the nonequilibrium carrier dynamics of a typical topological insulator Sb2Te3, where the electron system undergoes an ultrafast relaxation and releases through intra-band and inter-band scattering.
Abstract: In this study, we report the ultrafast excitation and dynamics of the carrier and photocurrent in a 3D typical topological insulator Sb2Te3. We utilize time-resolved optical pump-THz probe spectroscopy to explore the nonequilibrium carrier dynamics of Sb2Te3. The electron system undergoes an ultrafast relaxation and releases through intra-band and inter-band scattering. Additionally, THz emission spectroscopy is employed to investigate the different ultrafast photocurrents in Sb2Te3 through tuning the polarization of excitation pulses and rotating the sample's azimuthal angle. We distinguish the different ultrafast photocurrents driven by the linear photogalvanic effect, circular photogalvanic effect, and thermoelectric effect. Our results potentially enable an all-optical modulation of THz emission without any external bias field, which could play an important role in the development of topological insulator-based high-speed THz optoelectronic and opto-spintronic devices.
TL;DR: In this paper, a metamaterial absorber based on graphene and vanadium dioxide (VO2) was proposed to achieve higher integration, compatibility, and a more adaptable adjustable range.
TL;DR: The experimental results indicate that by introducing a polymer coating, a maximum gain factor of 3.46 and 3.21 is attained for the signal amplitude and signal-to-noise ratio (SNR) when compared to traditional LITES that using only a bare QTF.
Abstract: A novel laser-induced thermoelastic spectroscopy (LITES) sensor based on a polymer-coated quartz tuning fork (QTF) is reported. Two types of polymer films with different thicknesses are deposited on commercially available QTF to improve the conversion efficiency of laser energy deposition into vibration. CO2 was selected as the target analyte for validation measurements. The experimental results indicate that by introducing a polymer coating, a maximum gain factor of 3.46 and 3.21 is attained for the signal amplitude and signal-to-noise ratio (SNR), respectively, when compared to traditional LITES that using only a bare QTF. A minimum detectable concentration of 0.181% can be obtained, corresponding to a normalized noise equivalent absorption coefficient (NNEA) of 1.74×10−11 cm−1·W·Hz−1/2, and the measurement precision is approximately 0.06% with an averaging time of 200 s. Here, we show what we believe is the first demonstration of polymer coated QTF for LITES sensing, compared with custom QTF, the design has the virtues of lower cost, simple and easy-to-operate, is a promising new strategy for sensitive trace gas analysis.
TL;DR: In this article, the authors proposed several all-silicon metasurfaces to achieve multifunctional designs and simultaneous modulation of amplitude and phase profiles in the terahertz (THz) band.
Abstract: Integrating independent wavefront controls into one device can meet the increasing demand for high-capacity flat electromagnetic devices. Simultaneously and independently controlling the amplitude and phase is pivotal for completely manipulating the propagation of electromagnetic waves. Here, we propose several all-silicon metasurfaces to achieve multifunctional designs and simultaneous modulation of amplitude and phase profiles in the terahertz (THz) band. These metasurfaces integrate two degrees of freedom of the propagation phase and Pancharatnam-Berry (PB) phase. To illustrate the feasibility of this design, three schematic functions are shown below: a three-channel vortex beam generator, a controllable intensity ratio of co- and cross-polarizations corresponding to the incident circular polarization (CP), and a bifocal metasurface that is capable of generating two off-axis vortices with controllable power allocation. A sample is fabricated to specifically verify the amplitude and phase modulation of this design. The experimental results agree well with the simulations and validate the good performances of our proposals. This approach for directly generating an editable amplitude and phase may provide a new choice to design ultra-thin photonic devices.
TL;DR: In this paper, a bifocal metasurface is designed to focus on one circularly polarized component as a point and spin-opposite components as a vortex under the linearly polarized (LP) incidence.
Abstract: Conventionally, the realization of polarization transformation and wavefront manipulation in metasurfaces relies on the Pancharatnam-Berry (PB) phase together with the dynamic phase. However, the reported polarization transformation and wavefront manipulation were limited to spin-dependent wavefront manipulation for circular polarization (CP). To obtain more abundant functions, we propose a novel technology that relies on the dynamic phase with a spatial interleaving unit arrangement. With the functions of a quarter wave plate, the metasurfaces we designed can achieve multiple wavefront manipulations which are not only for the spin polarization transformation but also for the linear polarization transformation. Specifically, we design a bifocal metasurface, which can focus on one circularly polarized component as a point and spin-opposite component as a vortex under the linearly polarized (LP) incidence. With the further adjustment of the unit arrangement, the left-hand circularly polarized (LCP) and right-hand circularly polarized (RCP) components under the LP incidence can be refocused on the same point and then composited, resulting in a new LP exit wave. Furthermore, we prove theoretically that the desired x-LP component and y-LP component under the arbitrary CP incidence can also be manipulated independently. We believe that the versatility of this method will provide a novel platform for the development of terahertz integrated photonics.
TL;DR: In this paper, a new kind of photonic crystal fiber with D-shaped air holes in core region was proposed for terahertz (THz) region and numerical simulation results showed that the proposed PCF has a flat dispersion of 009 ± 028 ps/THz/cm at 08-12 THz at 1 THz, an ultra-high birefringence of 00595, a low effective material loss (EML) of 00557 cm−1, and dispersion that can be considered zero.
Abstract: High-performance photonic crystal fiber (PCF) has an important impact on the development of the full potential of complex terahertz systems A new kind of PCF with D-shaped air holes in core region was proposed for terahertz (THz) region The numerical simulation results showed that the proposed PCF has a flat dispersion of 009 ± 028 ps/THz/cm at 08-12 THz At 1 THz, an ultra-high birefringence of 00595, a low effective material loss (EML) of 00557 cm−1, and dispersion that can be considered zero were obtained In addition, other characteristics of the proposed PCF were strictly analyzed, such as confinement loss, bending loss, and effective mode area The PCF is expected to be used for short distance propagation of terahertz, polarization maintaining and sensing applications of terahertz waves
TL;DR: In this paper, an all-silicon chiral meta-atom which can realize spin-selective transmission in a dual band was proposed, and a terahertz metasurface with spin selective transmission through phase arrangement was designed by using CHs satisfying a gradient geometric phase, which can generate a focused right-hand circularly polarized (RCP) beam which is focused at a distance of 4.8 mm from the exit surface of the CH.
Abstract: Chiral metasurfaces which can achieve different optical responses for left-handed and right-handed circularly polarized (CP) light have been proposed. Most of the research studies on chiral metasurfaces focus on improving circular dichroism (CD) and realizing dynamic manipulation of the chiro-optical response. However, there have only been a few reports on the multi-band chiro-optical response. Here, we propose an all-silicon chiral meta-atom which can realize spin-selective transmission in a dual band. In addition, a terahertz metasurface with spin-selective transmission through phase arrangement is designed by using chiral meta-atoms satisfying a gradient geometric phase. Under left-hand circularly polarized (LCP) incidence, the metasurface generates a focused right-hand circularly polarized (RCP) beam which is focused at a distance of 4.8 mm from the exit surface of the metasurface. Our work broadens the concept of metasurface design and may attract more researchers’ attention on the applications of chiral metasurfaces.
TL;DR: In this article, a wideband optical-detection strategy based on the thermoelastic effect of a coatingenhanced quartz tuning fork (QTF) and study the feasibility of using an atomic force probe operating in contact mode to monitor the vibration is presented.
Abstract: Sensitive and broadband infrared sensors are required for security and medical applications, as few can rapidly and sensitively detect infrared without uncooled devices. Here, we report a wideband optical-detection strategy based on the thermoelastic effect of a coating-enhanced quartz tuning fork (QTF) and study the feasibility of using an atomic force probe operating in contact mode to monitor the vibration. Graphene oxide (GO) and polydimethylsiloxane (PDMS) coating were applied on the QTF’s surface to improve the light absorption and the thermal–mechanical conversion efficiency. Experimental results showed that the bi-layer coatings yielded a maximum gain factor of 8 in response amplitude and signal-to-noise ratio (SNR) than that of a bare QTF, respectively. Lasers with wavelengths of 1512 nm and 10.6 µm were used as the typical representative light source to test the photoresponse of the QTF detector. The device displays a broadband photoresponse covering the near-infrared to mid-infrared range at room temperature, high performance with the maximum photoresponsivity of 85.76 V·mW−1, and 1σ detection limit of 0.056 µW; the lowest noise equivalent power (NEP) of 1.35 nW·Hz-1/2 and 43.9 ms response speed is also achieved. The preparation process of detector is simple and easy to implement; the resulting device exhibits high responsivity and wide wavelength response ranging at least from 1512 to 10600 nm, compared with custom QTF; and the surface coating strategy potentially enables the construction of a new class of low-cost photodetection sensors operated at room temperature.
TL;DR: In this paper, two types of spatially interlaced metasurface OAM superposition state generators are designed and experimentally verified, which realize the generation of polarization-dependent single or multiple terahertz vortex interference beams.
Abstract: The superposition state of photonic orbital angular momentum (OAM) has more degrees of freedom than pure photonic orbital angular momentum, with rich physical implications and engineering application possibilities. Here we propose a scheme for polarization multiplexed terahertz OAM superposition state generation using an all-silicon metasurface. Two types of spatially interlaced metasurface OAM superposition state generators are designed and experimentally verified, which realize the generation of polarization-dependent single or multiple terahertz vortex interference beams. The first type of metasurface consists of polarization-maintaining silicon pillar arrays, which can switch the transmitted terahertz beam between different OAM superposition states. The analyzer direction of the superposition state is always consistent with the incident polarization. The second type of metasurface introduces units with a polarization conversion function, so that the analyzer direction of the OAM superposition state under different incident polarizations is always kept unchanged. In addition, the proposed metasurfaces can also generate a longitudinal electric field component and manipulate the superposition state of OAM. Both types of metasurfaces show excellent performance of efficient generation and switching of terahertz OAM superposition states. This method provides a new idea for photonic OAM manipulation based on metasurfaces.
TL;DR: In this paper, a novel kind of all-silicon chiral metasurface is proposed by introducing destructive interference between achiral meta-atoms, which can be used to generate various interesting functions, such as beam control and vortex generator.
Abstract: Chiral metasurfaces have different electromagnetic responses with circularly polarized lights, showing as circular dichroism and optical activity. Here, a novel kind of all-silicon chiral metasurface is proposed by introducing destructive interference between achiral meta-atoms. The maximum value of circular dichroism spectra can reach 0.49. By adding an antireflective layer at the side of the silicon substrate, the maximum circular dichroism reaches 0.54. What is more, the bandwidth of circular dichroism greater than 0.4 reaches 0.15 THz. Two samples are fabricated to verify the feasibility of this scheme, and the experimental results are in good agreement with the simulations. In addition, the proposed scheme can also be used to generate various interesting functions, such as beam control and vortex generator. This flexible and efficient implementation solution of chiral metasurface can bring new ideas to the development of chiral devices in the future.
TL;DR: Isoxazolone-based crystals are one of the important molecular type nonlinear optical crystals, which can exhibit good output properties in the terahertz region as mentioned in this paper.
Abstract: Isoxazolone-based crystals are one of the important molecular type nonlinear optical crystals, which can exhibit good output properties in the terahertz region. In this work, by rational steric gro...