查看更多>>摘要：Whispering-gallery-mode[WGM]microresonators can greatly enhance light-matter interaction,making them indispen-sable units for frequency conversion in nonlinear optics.Efficient nonlinear wave mixing in microresonators requires strin-gent simultaneous optical resonance and phase-matching conditions.Thus,it is challenging to achieve efficient frequency conversion over a broad bandwidth.Here,we demonstrate broadband second-harmonic generation[SHG]in the x-cut thin-film lithium niobate[TFLN]microdisk with a quality factor above 107 by applying the cyclic quasi-phase-matching[CQPM]mechanism,which is intrinsically applicable for broadband operation.Broadband SHG of continuous-wave laser with a maxi-mum normalized conversion efficiency of～15％o/mW is achieved with a bandwidth spanning over 100 nm in the telecom-munication band.Furthermore,broadband SHG of femtosecond lasers,supercontinuum lasers,and amplified spontaneous emission in the telecommunication band is also experimentally observed.The work is beneficial for integrated nonlinear photonics devices like frequency converters and optical frequency comb generator based on second-order nonlinearity on the TFLN platform.
查看更多>>摘要：In this review paper,we discuss the properties and applications of photonic computing and analog signal processing.Photonic computational circuits have large operation bandwidth,low power consumption,and fine frequency control,ena-bling a wide range of application-specific computational techniques that are impossible to implement using traditional electrical and digital hardware alone.These advantages are illustrated in the elegant implementation of optical steganog-raphy,the real-time blind separation of signals in the same bandwidth,and the efficient acceleration of artificial neural network inference.The working principles and use of photonic circuits for analog signal processing and neuromorphic computing are reviewed and notable demonstrated applications are highlighted.
查看更多>>摘要：Vortex waves with orbital angular momentum[OAM]are a highly active research topic in various fields.In this paper,we design and investigate cylindrical metagratings[CMs]with an even number of unit cells that can efficiently achieve vortex localization and specific OAM selective conversion.The multifunctional manipulation of vortex waves and the new OAM conservation law have further been confirmed through analytical calculations and numerical simulations.In addition,we qualitatively and quantitatively determine the OAM range for vortex localization and the OAM value of vortex selective conversion and also explore the stability for performance and potential applications of the designed structure.This work holds potential applications in particle manipulation and optical communication.
查看更多>>摘要：Lithium niobate is a material that exhibits outstanding electro-optic,nonlinear optical,acousto-optic,piezoelectric,photo-refractive,and pyroelectric properties.A thin-film lithium niobate photonic crystal can confine light in the sub-wavelength scale,which is beneficial to the integration of the lithium niobate on-chip device.The commercialization of the lithium niobate on insulator gives birth to the emergence of high-quality lithium niobate photonic crystals.In order to provide guidance to the research of lithium niobate photonic crystal devices,recent progress about fabrication,characterization,and applications of the thin-film lithium niobate photonic crystal is reviewed.The performance parameters of the different devices are compared.
查看更多>>摘要：This study investigated direct fluorescence generation from a nematic liquid crystal[NLC]NJU-LDn-4 under femtosecond laser excitation.The absorption,transmittance,excitation,and emission spectra of the NLC were assessed.The relationship between the femtosecond pump power and fluorescence intensity was analyzed,revealing a quadratic increase and indi-cating that two-photon absorption[2PA]is the primary fluorescence mechanism.The LC microstructure was designed using photoalignment technology,allowing the generated fluorescence to reflect the corresponding structure.This research can establish a foundation fortunable LC microstructured fluorescence,with potential applications in fluorescence microscopy and optoelectronics.
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