基于PPM(Pulse Position Modulation)硬判决检错的ARQ-FSO(Automatic Repeat Request-Free Space Optical)通信系统结合了PPM硬判决和新的ARQ协议.该系统以PPM硬判决的结果代替了传统ARQ的监督码元作为数据的检错依据,同时只重传数据包...基于PPM(Pulse Position Modulation)硬判决检错的ARQ-FSO(Automatic Repeat Request-Free Space Optical)通信系统结合了PPM硬判决和新的ARQ协议.该系统以PPM硬判决的结果代替了传统ARQ的监督码元作为数据的检错依据,同时只重传数据包里面译码失败部分的PPM符号,消除了传统ARQ中用来检错的信息冗余,提高了系统的效率.理论分析表明该方案能够有效地改善硬判决误码率,其通过率也优于传统ARQ,适用于较低误码率、低复杂度的自由空间光通信场景.展开更多
Two types of one-dimensional(1D)anti-PT-symmetric periodic ring optical waveguide networks,consisting of gain and loss materials,are constructed.The singular optical propagation properties of these networks are invest...Two types of one-dimensional(1D)anti-PT-symmetric periodic ring optical waveguide networks,consisting of gain and loss materials,are constructed.The singular optical propagation properties of these networks are investigated.The results show that the system composed of gain materials exhibits characteristics of ultra-strong transmission and bidirectional reflection.Conversely,the system composed of loss materials demonstrates equal transmittance and reflectance at some frequencies.In both the systems,a new type of total reflection phenomenon is observed.When the imaginary part of the refractive indices of waveguide segments is smaller than 10-5,the system shows bidirectional transparency with the transmittance tending to be 1 and reflectivity to be smaller than 10-8 at some bands.When the refractive indices of the waveguide segments are real,the system will be bidirectional transparent at the full band.These findings may deepen the understanding of anti-PT-symmetric optical systems and optical waveguide networks,and possess potential applications in efficient optical energy storage,ultra-sensitive optical filters,ultra-sensitive all-optical switches,integrated optical chips,stealth physics,and so on.展开更多
This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility,which can be used in bioimaging.Fluorescence emission at 410 nm is observed in the quantum dot unde...This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility,which can be used in bioimaging.Fluorescence emission at 410 nm is observed in the quantum dot under 760-nm laser excitation.These biocompatible quantum dots exhibit a two-photon cross-section of 9.1×105 GM(1 GM=10-50 cm4·s/photon).Two-photon excited laser scanning microscopic images show that cells co-cultured with ZnSe quantum dots are found in the blue channel at a fluorescence intensity that is 14.5 times that of control cells not cocultured with quantum dots.After incubating zebrafish larvae with ZnSe quantum dots for 24 h,the fluorescence intensity of the yolk sac stimulated by ultraviolet light is 2.9 times that of the control group.The proposed material shows a great potential application in biological imaging.展开更多
In this paper, a plasmonics refractive index sensor with the semiring-stub system coupled to a bus waveguide is proposed. The structure can achieve wavelength band tunable and ultra-sharp Fano resonance. The coupling ...In this paper, a plasmonics refractive index sensor with the semiring-stub system coupled to a bus waveguide is proposed. The structure can achieve wavelength band tunable and ultra-sharp Fano resonance. The coupling mechanism between the bright mode and dark mode is investigated in detail, and apparent plasmon induced transparency(PIT) is realized on the resonance wavelength. The full width at half maximum(FWHM) of the resonant wavelength is modulated by adjusting the coupled distance. The sensitivity and figure of merit(FOM) of the proposed sensor can reach up to 600 nm/RIU and 120 on the visible region, respectively, and this performance can be helpful for designing the photonic integrated circuit and optical communication, in addition, it can be applied for bio-sensing.展开更多
Experimental results demonstrate that the band gap of colloidal suspension crystal changes with both the thickness of crystal and the dispersity of micro-spheres. As the thickness decreases, a red shift of band gap is...Experimental results demonstrate that the band gap of colloidal suspension crystal changes with both the thickness of crystal and the dispersity of micro-spheres. As the thickness decreases, a red shift of band gap is observed, and there is a maximum of red shift. The values of the maximum red shifts are dependent on the standard deviations of micro-spheres. The experimental results are consistent with theoretical calculation. As the colloidal suspension crystal is assembled from micro-spheres with a standard deviation of 8.4% in a thick cell, an incident angles independent broadband is observed, which is explained as an amorphous structure. Two amorphous models are discussed.展开更多
By its unparalleled capacity to manipulate optical parameters,metasurfaces demonstrate the ability to simultaneously manipulate the amplitude and phase of incident light.Exhibiting both near-field nanoprinting images ...By its unparalleled capacity to manipulate optical parameters,metasurfaces demonstrate the ability to simultaneously manipulate the amplitude and phase of incident light.Exhibiting both near-field nanoprinting images and far-field holography images is a quintessential illustration of this capability.In preceding investigations,image multiplexing commonly transpires within the single polarization state or orthogonal polarization states,thereby exhibiting a deficiency in terms of information security when contrasted with the nonorthogonal polarization states.In this research,a multifunctional metasurface with the capability of exhibiting four-channel images has been proposed by using a nanobrick as a quarter-wave plate.Through the adjustment of the orientation angles of each nanobrick,nanoprinting can be displayed under both linearly and circularly polarized light.Building on this,the propagation phase is combined with the geometric phase to generate diverse phase delays,enabling the metasurface to be multiplexed under two nonorthogonal polarization states to achieve four-channel image displays.Intriguingly,bidirectional nanoprinting and bidirectional holography can be achieved by altering the direction of incidence polarization states.The proposed metasurface platform can open new possibilities for creating compact multifunctional optical devices,while also enhancing applications in multichannel image displays,information anticounterfeiting,and encryption.展开更多
文摘基于PPM(Pulse Position Modulation)硬判决检错的ARQ-FSO(Automatic Repeat Request-Free Space Optical)通信系统结合了PPM硬判决和新的ARQ协议.该系统以PPM硬判决的结果代替了传统ARQ的监督码元作为数据的检错依据,同时只重传数据包里面译码失败部分的PPM符号,消除了传统ARQ中用来检错的信息冗余,提高了系统的效率.理论分析表明该方案能够有效地改善硬判决误码率,其通过率也优于传统ARQ,适用于较低误码率、低复杂度的自由空间光通信场景.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674107,61475049,11775083,61774062,and 61771205).
文摘Two types of one-dimensional(1D)anti-PT-symmetric periodic ring optical waveguide networks,consisting of gain and loss materials,are constructed.The singular optical propagation properties of these networks are investigated.The results show that the system composed of gain materials exhibits characteristics of ultra-strong transmission and bidirectional reflection.Conversely,the system composed of loss materials demonstrates equal transmittance and reflectance at some frequencies.In both the systems,a new type of total reflection phenomenon is observed.When the imaginary part of the refractive indices of waveguide segments is smaller than 10-5,the system shows bidirectional transparency with the transmittance tending to be 1 and reflectivity to be smaller than 10-8 at some bands.When the refractive indices of the waveguide segments are real,the system will be bidirectional transparent at the full band.These findings may deepen the understanding of anti-PT-symmetric optical systems and optical waveguide networks,and possess potential applications in efficient optical energy storage,ultra-sensitive optical filters,ultra-sensitive all-optical switches,integrated optical chips,stealth physics,and so on.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61774062 and U20A20206)the Science and Techology Program of Guangzhou City,China(Grant No.2019050001)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2018A030313854 and2016A030308010)。
文摘This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility,which can be used in bioimaging.Fluorescence emission at 410 nm is observed in the quantum dot under 760-nm laser excitation.These biocompatible quantum dots exhibit a two-photon cross-section of 9.1×105 GM(1 GM=10-50 cm4·s/photon).Two-photon excited laser scanning microscopic images show that cells co-cultured with ZnSe quantum dots are found in the blue channel at a fluorescence intensity that is 14.5 times that of control cells not cocultured with quantum dots.After incubating zebrafish larvae with ZnSe quantum dots for 24 h,the fluorescence intensity of the yolk sac stimulated by ultraviolet light is 2.9 times that of the control group.The proposed material shows a great potential application in biological imaging.
基金supported by the National Natural Science Foundation of China(Nos.61774062,11674107,61475049 and 11674109)the Natural Science Foundation of Guangdong Province in China(No.2016A030313443)
文摘In this paper, a plasmonics refractive index sensor with the semiring-stub system coupled to a bus waveguide is proposed. The structure can achieve wavelength band tunable and ultra-sharp Fano resonance. The coupling mechanism between the bright mode and dark mode is investigated in detail, and apparent plasmon induced transparency(PIT) is realized on the resonance wavelength. The full width at half maximum(FWHM) of the resonant wavelength is modulated by adjusting the coupled distance. The sensitivity and figure of merit(FOM) of the proposed sensor can reach up to 600 nm/RIU and 120 on the visible region, respectively, and this performance can be helpful for designing the photonic integrated circuit and optical communication, in addition, it can be applied for bio-sensing.
基金This work was supported by the National Natu- ral Science Foundation of China (No. 19934002 and 10274108) the National "863" Project of China (No.2003AA311022)+1 种基金 the National "973" Project of China (No. 2003CB314901)Natural Science Foundation ofGuang
文摘Experimental results demonstrate that the band gap of colloidal suspension crystal changes with both the thickness of crystal and the dispersity of micro-spheres. As the thickness decreases, a red shift of band gap is observed, and there is a maximum of red shift. The values of the maximum red shifts are dependent on the standard deviations of micro-spheres. The experimental results are consistent with theoretical calculation. As the colloidal suspension crystal is assembled from micro-spheres with a standard deviation of 8.4% in a thick cell, an incident angles independent broadband is observed, which is explained as an amorphous structure. Two amorphous models are discussed.
基金supported by the National Natural Science Foundation of China (NSFC) (Nos.62175070 and 61774062)the Natural Science Foundation of Guangdong Province (No.2021A1515010352)the Science and Technology Program of Guangzhou (No.2019050001)。
文摘By its unparalleled capacity to manipulate optical parameters,metasurfaces demonstrate the ability to simultaneously manipulate the amplitude and phase of incident light.Exhibiting both near-field nanoprinting images and far-field holography images is a quintessential illustration of this capability.In preceding investigations,image multiplexing commonly transpires within the single polarization state or orthogonal polarization states,thereby exhibiting a deficiency in terms of information security when contrasted with the nonorthogonal polarization states.In this research,a multifunctional metasurface with the capability of exhibiting four-channel images has been proposed by using a nanobrick as a quarter-wave plate.Through the adjustment of the orientation angles of each nanobrick,nanoprinting can be displayed under both linearly and circularly polarized light.Building on this,the propagation phase is combined with the geometric phase to generate diverse phase delays,enabling the metasurface to be multiplexed under two nonorthogonal polarization states to achieve four-channel image displays.Intriguingly,bidirectional nanoprinting and bidirectional holography can be achieved by altering the direction of incidence polarization states.The proposed metasurface platform can open new possibilities for creating compact multifunctional optical devices,while also enhancing applications in multichannel image displays,information anticounterfeiting,and encryption.
