查看更多>>摘要：Organic-inorganic hybrid perovskite formamidinium lead bromide nanosheet[FAPbBr3 NS]is regarded as a superior sub-stance used to construct optoelectronic devices.However,its uncontrollable stability seriously affects its application in the field of photodetectors.In this paper,FAPbBr3 is combined with cadmium sulfide nanobelt[CdS NB]to construct a hybrid device that greatly improves the stability and performance of the photodetector.The response of the FAPbBr3 NS/CdS NB detector under 490 nm light illumination reaches 5712 A/W,while the response of the FAPbBr3 photodetector under equiv-alent conditions is only 25.45 A/W.The photocurrent of the FAPbBr3 NS/CdS NB photodetector is nearly 80.25％of the initial device after exposure to air for 60 days.The difference in electric field distribution between the single material device and the composite device is simulated by the finite-difference time-domain method.It shows the advantages of composite devices in photoconductive gain and directly promotes the hybrid device performance.This paper presents a new possibility for high stability,fast response photodetectors.
查看更多>>摘要：Based on the transverse-longitudinal mapping of Bessel beams,we propose a simple method to construct a self-similar Bessel-like beam whose transverse profile maintains a stretched form during propagation.Specifically,the propagating-variant width of this beam can be flexibly predesigned.We experimentally demonstrate three types of self-similar Bessel-like beams whose width variations are linear,piecewise,and period functions of propagation distance,respectively.The experimental results match well with the theoretical predictions.We also demonstrate that our approach enables the generation of self-similar higher-order vortex Bessel-like beams.
查看更多>>摘要：Recently,there has been increased attention toward 3D imaging using single-pixel single-photon detection[also known as temporal data]due to its potential advantages in terms of cost and power efficiency.However,to eliminate the symmetry blur in the reconstructed images,a fixed background is required.This paper proposes a fusion-data-based 3D imaging method that utilizes a single-pixel single-photon detector and millimeter-wave radar to capture temporal histograms of a scene from multiple perspectives.Subsequently,the 3D information can be reconstructed from the one-dimensional fusion temporal data by using an artificial neural network.Both the simulation and experimental results demonstrate that our fusion method effectively eliminates symmetry blur and improves the quality of the reconstructed images.
查看更多>>摘要：Phase-coherent multi-tone lasers play a critical role in atomic,molecular,and optical physics.Among them,the Raman opeartion laser for manipulating atomic hyperfine qubits requires gigahertz bandwidth and low phase noise to retain long-term coherence.Raman operation lasers generated by directly modulated and frequency-multipled infrared lasers are compact and stable but lack feedback control to actively suppress the phase noise,which limits their performance in practical applications.In this work,we employ a fiber electro-optical modulator driven by a voltage-controlled oscillator[VCO]to modulate a monochromatic laser and employ a second-harmonic generation process to convert it to the visible domain,where the beat note of the Raman operation laser is stabilized by controlling the output frequency of VCO with a digital phase-locked loop[PLL].The low-frequency phase noise is effectively suppressed compared to the scheme without active feedback and it reaches-80 dBc/Hz@5 kHz with a 20 kHz loop bandwidth.Furthermore,this compact and robust scheme effectively reduces the system,s complexity and cost,which is promising for extensive application in atomic,molecular,and optical physics.
查看更多>>摘要：We demonstrate a high-performance acousto-optic modulator-based bi-frequency interferometer,which can realize either beating or beating free interference for a single-photon level quantum state.Visibility and optical efficiency of the inter-ferometer are(99.5±0.2)％and(95±1)％,respectively.The phase of the interferometer is actively stabilized by using a dithering phase-locking scheme,where the phase dithering is realized by directly driving the acousto-optic modulators with a specially designed electronic signal.We further demonstrate applications of the interferometer in quantum technology,including bi-frequency coherent combination,frequency tuning,and optical switching.These results show the interferom-eter is a versatile device for multiple quantum technologies.
查看更多>>摘要：Polarizers have always been an important optical component for optical engineering and have played an indispensable part of polarization imaging systems.Metasurface polarizers provide an excellent platform to achieve miniaturization,high res-olution,and low cost of polarization imaging systems.Here,we proposed freeform metasurface polarizers derived by adjoint-based inverse design of a full-Jones matrix with gradient-descent optimization.We designed multiple freeform polarizers with different filtered states of polarization[SOPs],including circular polarizers,elliptical polarizers,and linear polarizers that could cover the full Poincaré sphere.Note that near-unitary polarization dichroism and the ultrahigh polari-zation extinction ratio[ER]reaching 50 dB were achieved for optimized circular polarizers.The multiple freeform polarizers with filtered polarization state locating at four vertices of an inscribed regular tetrahedron of the Poincaré sphere are designed to form a full-Stokes parameters micropolarizer array.Our work provides a novel approach,we believe,for the design of meta-polarizers that may have potential applications in polarization imaging,polarization detection,and communication.
查看更多>>摘要：We demonstrate a high-Q perfect light absorber based on all-dielectric doubly-resonant metasurface.Leveraging bound states in the continuum[BICs]protected by different symmetries,we manage to independently manipulate the Qfactors of the two degenerate quasi-BICs through dual-symmetry perturbations,achieving precise matching of the radiative and non-radiative Q factors for degenerate critical coupling.We achieve a narrowband light absorption with a＞600 0 factor and a＞99％absorptance at λ0=1550 nm on an asymmetric germanium metasurface with a 0.2λ0 thickness.Our work provides a new strategy for engineering multiresonant metasurfaces for narrowband light absorption and nonlinear applications.
查看更多>>摘要：Optical tweezers have proved to be a powerful tool with a wide range of applications.The gradient force plays a vital role in the stable optical trapping of nano-objects.The scalar method is convenient and effective for analyzing the gradient force in traditional optical trapping.However,when the third-order nonlinear effect of the nano-object is stimulated,the scalar method cannot adequately present the optical response of the metal nanoparticle to the external optical field.Here,we propose a theoretical model to interpret the nonlinear gradient force using the vector method.By combining the optical Kerr effect,the polarizability vector of the metallic nanoparticle is derived.A quantitative analysis is obtained for the gra-dient force as well as for the optical potential well.The vector method yields better agreement with reported experimental observations.We suggest that this method could lead to a deeper understanding of the physics relevant to nonlinear optical trapping and binding phenomena.
查看更多>>摘要：We propose and experimentally demonstrate the programmable photonic radio frequency[RF]filters based on an inte-grated Fabry-Pérot laser with a saturable absorber[FP-SA].Owing to the high output power and the relative flatness spec-trum of the FP-SA laser,only a waveshaper and an erbium-doped fiber amplifier[EDFA]were needed,which can greatly reduce the complexity of the system.The sinc filter employed 87 taps,representing a record-high tap number and resulting in a 3-dB bandwidth of 0.27 GHz and a quality factor of 148.Furthermore,Gaussian apodization enabled the out-of-band rejection of the filter to reach 34 dB and the center frequency to be finely tuned over a wide range,spanning from 4 to 14 GHz.These results indicate that the proposed scheme could provide a promising guideline for the photonic RF filters that demand both high reconfigurability and greatly reduced size and complexity.
查看更多>>摘要：Electromagnetic topological chiral edge states mimicking the quantum Hall effect have attracted a great deal of attention due to their unique features of free backscattering and immunity against sharp bends and defects.However,the matching techniques between classical waveguides and the topological one-way waveguide deserve more attention for real-world applications.In this paper,a highly efficient conversion structure between a classical rectangular waveguide and a topo-logical one-way waveguide is proposed and demonstrated at the microwave frequency,which efficiently converts classical guided waves to topological one-way edge states.A tapered transition is designed to match both the momentum and impedance of the classical guided waves and the topological one-way edge states.With the conversion structure,the waves generated by a point excitation source can be coupled to the topological one-way waveguide with very high coupling effi-ciency,which can ensure high transmission of the whole system[i.e.,from the source and the receiver].Simulation and measurement results demonstrate the proposed method.This investigation is beneficial to the applications of topological one-way waveguides and opens up a new avenue for advanced topological and classical integrated functional devices and systems.
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