●Multiple evanescent white dot syndrome(MEWDS)is a rare fundus disease,characterized by acute vision loss and visual field defects.Many previous studies have explained the possible pathogenesis and clinical features ...●Multiple evanescent white dot syndrome(MEWDS)is a rare fundus disease,characterized by acute vision loss and visual field defects.Many previous studies have explained the possible pathogenesis and clinical features of primary MEWDS.However,as the number of reported cases increases,secondary MEWDS occurs in other related retinal diseases and injuries,exhibiting some special characteristics.The associated retinal diseases include multifocal choroiditis/punctate inner choroidopathy(MFC/PIC),acute zonal occult outer retinopathy,best vitelliform macular dystrophy,pseudoxanthoma elasticum,and ocular toxoplasmosis.The related retinal injury is laser photocoagulation,surgery,and trauma.Although primary MEWDS often have a self-limiting course,secondary MEWDS may require treatment in some cases,according to the severity of concomitant diseases and complications.Notably,MEWDS secondary to MFC/PIC that is prone to forming choroidal neovascularization and focal choroidal excavation,needs positive treatment with corticosteroids.The possible underlying pathogenesis of secondary MEWDS is the exposure of choroidal antigen after the disruption of Bruch’s membrane.The MEWDS-related features in secondary MEWDS are still evanescent under most circumstances.Its prognosis and treatment depend on the severity of complications.Current studies propose that the etiology is associated with immune factors,including viral infection,inflammation in choroid and Bruch’s membrane,and antigen exposure caused by retinal and/or choroidal insults.More pathogenic studies should be conducted in the future.Accurate diagnosis for secondary MEWDS could benefit patients in aspects of management and prognosis.展开更多
Using a nanoscale silica fiber taper,light can be efficiently coupled into a single ZnO nanowire by means of evanescent coupling. The method is valid for launching light into a single nanowire in the ultraviolet to in...Using a nanoscale silica fiber taper,light can be efficiently coupled into a single ZnO nanowire by means of evanescent coupling. The method is valid for launching light into a single nanowire in the ultraviolet to infrared range with a coupling efficiency of 25%, Low-loss optical guiding of ZnO nanowires is demonstrated, and the photoluminescence of a single ZnO nanowire is also observed. Compared to conventional approaches in which a lensfocused laser beam is used to excite nanowires at specific wavelengths,this evanescent coupling approach has advantages such as high coupling efficiency and broad-band validity, and it is promising for the optical characterization of semiconductor nanowires or nanoribbons.展开更多
A novel Whispering-Gallery-Mode （WGM） fibre laser, emitting linearly polarised three-colour light, is demonstrated by pumping and gain coupling with evanescent waves. The pump light is longitudinally coupled into a ...A novel Whispering-Gallery-Mode （WGM） fibre laser, emitting linearly polarised three-colour light, is demonstrated by pumping and gain coupling with evanescent waves. The pump light is longitudinally coupled into a bare optical fibre immersed in a dye solution of lower refractive index. The dye molecules around the bare fibre are excited by the evanescent waves of pump light when they propagate along the fibre in a total internal reflection. When the pump beam within the fibre is a meridian beam, the WGM lasing emission from the fibre laser is a linearly polarised transverse electric wave, while it is a mixed wave of the linearly polarised transverse electric and magnetic waves if the pump beam is a skew beam within the fibre. Because the excited molecules are located within the evanescent field of WGM, a good spatial overlap between the dye gain and the evanescent field leads to a high pumping efficiency and a longer gain distance along the fibre. Once the bare fibre is inserted into three glass capillaries filled with Rhodamine 6G, 610 and 640 dye solutions, respectively, WGM laser oscillations at the wavelengths of 567-575, 605-614 and 656-666 nm occur simultaneously, and a linearly polarised three-colour lasing emission is achieved in a single optical fibre.展开更多
In this paper, we present the design, fabrication, and measurement of an evanescently coupled waveguide photode- tector operating at 1.55 gm, which mainly comprises a diluted waveguide, a single-mode rib waveguide and...In this paper, we present the design, fabrication, and measurement of an evanescently coupled waveguide photode- tector operating at 1.55 gm, which mainly comprises a diluted waveguide, a single-mode rib waveguide and a p-i-n photodiode with an extended optical matching layer. The optical characteristics of this structure are studied by using a three-dimensional finite-difference time-domain （3D FDTD） method. The photodetector exhibits a high 3-dB bandwidth of more than 35 GHz and a responsivity of 0.291 A/W at 1550 nm directly coupled with a cleaved fiber. Moreover, a linear response of more than 72-mW optical power is achieved, where a photocurrent of more than 21 mA is obtained at a reverse bias voltage of 3 V.展开更多
Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with ...Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with fluorescein angiography （FA） and electrophysiology suggested that MEWDS to be a disease in the retinal pigment epithelium （RPE） or outer retina, while recent studies with spectral- domain optical coherence tomography （SD-OCT） suggested it may be an outer retinal disease due to observation of hyperreflective material in outer retina and subtle disruptionsof the ellipsoid zone without RPE disruption.展开更多
To improve the sensitivity of protein microarray, a prism surface replaces the surface of the common microscope slide.The protein targets arrayed on the surface are hybridized and labelled by fluorescent probes. Evane...To improve the sensitivity of protein microarray, a prism surface replaces the surface of the common microscope slide.The protein targets arrayed on the surface are hybridized and labelled by fluorescent probes. Evanescent excitation occurs when the convergent laser reaches the surface, and a photomultiplier tube detects the emitted fluorescent signal. A two-dimensional actuator scans the whole surface to achieve planar laser excitation and fluorescence collection. The penetration depth of the evanescent field into the protein targets is only some hundred nanometers and can be controlled by different incident angle of the laser beam, so the undesired background signals are reduced dramatically and the detection sensitivity is improved by a factor of 50 to 100 comparing to confocal excitation. This approach can detect low abundance analytes without signal amplification.展开更多
We have studied the optical matching layers （OMLs） and external quantum efficiency in the evanescent coupling photodiodes （ECPDs） integrating a diluted waveguide as a fibre-to-waveguide coupler, by using the semi-...We have studied the optical matching layers （OMLs） and external quantum efficiency in the evanescent coupling photodiodes （ECPDs） integrating a diluted waveguide as a fibre-to-waveguide coupler, by using the semi-vectorial beam propagation method （BPM）. The physical basis of OML has been identified, thereby a general designing rule of OML is developed in such a kind of photodiode. In addition, the external quantum efficiency and the polarization sensitivity versus the absorption and coupling length are analysed. With an optical matching layer, the absorption medium with a length of 30μm could absorb 90% of the incident light at 1.55μm wavelength, thus the total absorption increases more than 7 times over that of the photodiode without any optical matching layer.展开更多
In this paper, we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency. High responsivity （〉 1 A/W）, hig...In this paper, we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency. High responsivity （〉 1 A/W）, high saturation power （〉 45 mA） in the static state and extremely low dark current density （0.04 pA/μm2） with 3 dB bandwidth at 13.4 GHz have been achieved.展开更多
The bi-dimensional optical lattices formed by several sets of laser evanescent standing waves propagating at the surface of a dielectric prism are investigated. The characteristics of the optical traps including their...The bi-dimensional optical lattices formed by several sets of laser evanescent standing waves propagating at the surface of a dielectric prism are investigated. The characteristics of the optical traps including their depths and the sizes are analysed. It is shown that the micro-optical lattice with a sub-half-wavelength size can be achieved by the interference of the selected evanescent waves. The scheme together with the recently developed atomic chip may be used for atomic quantum manipulation.展开更多
A discrete model of the Differential Evanescent Light Intensity (DELI) technique was developed to calculate and map 3D nanolayers thicknesses from the evanescent light intensity captured from optical waveguides. The m...A discrete model of the Differential Evanescent Light Intensity (DELI) technique was developed to calculate and map 3D nanolayers thicknesses from the evanescent light intensity captured from optical waveguides. The model was used for ultra-thin Pd nanometric layers sputtered on glass substrates. The layers thickness profiles were displayed in 3D and 1D profiles plots. The total thickness profiles of the ultra-thin Pd films obtained in the range of 1-10 nm were validated using AFM measurements. Based on the model developed the evanescent photon extraction parameter of the material was estimated.展开更多
To report the case of a patient who presented with idiopathic choroidal neovascularization(CNV)as the first sign of multiple evanescent white dot syndrome(MEWDS).A 25-year-old woman presented with recent onset of decr...To report the case of a patient who presented with idiopathic choroidal neovascularization(CNV)as the first sign of multiple evanescent white dot syndrome(MEWDS).A 25-year-old woman presented with recent onset of decreased vision and metamorphopsia in the right eye.The results of fundoscopic examination,fluorescein angiography,and optical coherence tomography(OCT) were compatible with a diagnosis of idiopathic CNV,which was treated with one intravitreal injection of bevacizumab.Five years later,the patient returned complaining of photopsia and decreased vision in the same eye.The fundoscopic examination showed typical signs of MEWDS.After 3 months,recurrence of CNV was observed in the same eye.In conclusion,idiopathic CNV might be the only manifestation of a subclinical occurrence of MEWDS.In this case,it was followed by a recurrence of MEWDS and subsequent reactivation of CNV.展开更多
A portable evanescent wave optic ?ber immunosensor was developed for detection of 2,4-dichlorophenoxyacetic acid(2,4-D) using a indirect competitive immunoassay. In this paper, hapten conjugates 2,4-D-OVA were immobil...A portable evanescent wave optic ?ber immunosensor was developed for detection of 2,4-dichlorophenoxyacetic acid(2,4-D) using a indirect competitive immunoassay. In this paper, hapten conjugates 2,4-D-OVA were immobilized with covalent binding methods. After pre-reacting, 2,4-D-antibody-Cy5.5 in sample specifically recognized the 2,4-D antigens binding sites on surface of the optical fiber probe. Under optimum conditions, 2,4-D could be detected in less than 18 min for each assay cycle. The regeneration of the optic ?ber surface allowed more than 200 times without losing performance. The limits of detection of 0.039 ug/L and the quantitative detection range of 0.47 - 81.02 ug/L were obtained when the concentration of 2,4-D was 1 mg/L. This immunosensor shows great potential in rapid simultaneous detection of 2,4-D in waters samples.展开更多
We design and fabricate a parallel system with 10 high speed side-illuminated evanescently coupled waveguide photodetectors （ECPDs）. The 10 ECPDs exhibit a uniform 3dB bandwidth of 20 GHz and low dark current of abo...We design and fabricate a parallel system with 10 high speed side-illuminated evanescently coupled waveguide photodetectors （ECPDs）. The 10 ECPDs exhibit a uniform 3dB bandwidth of 20 GHz and low dark current of about i nA at 2 V reverse bias. The 10 ECPDs also exhibit uniform photo-responsivity of about 0.23A/W with an active region of 5 × 25μmS. The photodetector array has a total bandwidth of more than 200 GHz and can be integrated with other optoelectronic devices.展开更多
It is pointed out that the evanescent light wave occurring at total reflection does not possess a transverse spin angular momentum as Bliokh, Bekshaev, and Nori claimed recently in (2014) Nature Communications, 5,3300...It is pointed out that the evanescent light wave occurring at total reflection does not possess a transverse spin angular momentum as Bliokh, Bekshaev, and Nori claimed recently in (2014) Nature Communications, 5,3300. This is not only because of the nonlocality of the photon spin but also because the evanescent wave is such a state whose angular momentum cannot be separated into spin and orbital parts.展开更多
Nanometric profiles of sputtered ultra-thin Pd layers with thicknesses in the range 1 - 10 nm were investigated by capturing the leaking evanescent light from optical waveguides. The Pd films were deposited by sputter...Nanometric profiles of sputtered ultra-thin Pd layers with thicknesses in the range 1 - 10 nm were investigated by capturing the leaking evanescent light from optical waveguides. The Pd films were deposited by sputtering on glass substratesalso servingas light waveguides. Calibrating the thickness values for the ultra-thin Pd films obtained from the sputtering rate combined with the DELI estimation technique, gave detailed 1Dand 3D morphological nanometric profiles of the deposited layers.展开更多
Usually, electromagnetic evanescent waves are some kinds of near fields. However, it looks as if the evanescent waves inside a cut-off waveguide had nothing to do with any near field. In this paper, we will show that ...Usually, electromagnetic evanescent waves are some kinds of near fields. However, it looks as if the evanescent waves inside a cut-off waveguide had nothing to do with any near field. In this paper, we will show that the evanescent waves inside a cut-off waveguide can also be regarded as the near fields of an aerial array.展开更多
In addition to offering morphological visualizations via capture of the spatial distributions of optical absorption,photoacoustic imaging technology can reveal abundant physical information about biological particles,...In addition to offering morphological visualizations via capture of the spatial distributions of optical absorption,photoacoustic imaging technology can reveal abundant physical information about biological particles,including their orientation,density,and viscoelasticity,through analysis of the pressure transients in the spectral domain.However,the low-amplitude wideband photoacoustic signals of intrinsic microscopic optically-absorbing objects under the action of confined photoacoustic excitation power continue to hinder simultaneous photoacoustic structural imaging and spectroscopic analysis of the nonfluorescent chromophores in living biological tissues because of the inadequate responses to photoacoustic impulses observed in most photoacoustic imaging setups that include piezoelectric transducers.Building upon a recently-developed optical evanescent wave sensor that can respond to ultrasound with high sensitivity over a broad frequency range,we propose in vivo spatial-spectral photoacoustic microscopy for recovery of structural imaging in three dimensions and characterization of anatomical features in the acoustic frequency domain.Label-free photoacoustic images of a living zebrafish are acquired in which spectroscopically-resolved differentiation of the microarchitecture is accessed,along with isometric micrometer-scale volumetric visualizations.The proposed imaging technology could potentially provide more comprehensive evaluations of the physiopathological status of living small animals.展开更多
In the realm of near-infrared spectroscopy,the detection of molecules has been achieved using on-chip waveguides and resonators.In the mid-infrared band,the integration and sensitivity of chemical sensing chips are of...In the realm of near-infrared spectroscopy,the detection of molecules has been achieved using on-chip waveguides and resonators.In the mid-infrared band,the integration and sensitivity of chemical sensing chips are often constrained by the reliance on off-chip light sources and detectors.In this study,we demonstrate an InAs/GaAsSb superlattice mid-infrared waveguide integrated detector.The GaAsSb waveguide layer and the InAs/GaAsSb superlattice absorbing layer are connected through evanescent coupling,facilitating efficient and highquality detection of mid-infrared light with minimal loss.We conducted a simulation to analyze the photoelectric characteristics of the device.Additionally,we investigated the factors that affect the integration of the InAs/GaAs⁃Sb superlattice photodetector and the GaAsSb waveguide.Optimal thicknesses and lengths for the absorption lay⁃er are determined.When the absorption layer has a thickness of 0.3μm and a length of 50μm,the noise equiva⁃lent power reaches its minimum value,and the quantum efficiency can achieve a value of 68.9%.The utilization of waveguide detectors constructed with Ⅲ-Ⅴ materials offers a more convenient means of integrating mid-infra⁃red light sources and achieving photoelectric detection chips.展开更多
A novel high sensitivity relative humidity(RH)sensor was proposed by using micro structure plastic optical fiber(POF)based on the surface plasmon resonance(SPR)effect and the evanescent wave(EW)loss.The micro structur...A novel high sensitivity relative humidity(RH)sensor was proposed by using micro structure plastic optical fiber(POF)based on the surface plasmon resonance(SPR)effect and the evanescent wave(EW)loss.The micro structure was fabricated on the POF and coated with a gold layer and agarose,adopting the sputtering and dip-coating technique.These construction effects on the attenuation of power caused by the SPR effect and the EW loss were used to perform RH detections.The agarose9s different refractive indexes(RIs)caused fluctuations in the transmission power when the humidity increased.The demonstrated experimental results showed that the proposed sensor achieved a linear response from 20%RH to 80%RH with a high sensitivity of 0.595μW/%.The proposed sensor had the advantages of fast response and recovery.Furthermore,the temperature dependence and the repeatability test of the sensor were also performed.展开更多
Abbe’s resolution limit,one of the best-known physical limitations,poses a great challenge for any wave system in imaging,wave transport,and dynamics.Originally formulated in linear optics,the Abbe limit can be broke...Abbe’s resolution limit,one of the best-known physical limitations,poses a great challenge for any wave system in imaging,wave transport,and dynamics.Originally formulated in linear optics,the Abbe limit can be broken using nonlinear optical interactions.We extend the Abbe theory into a nonlinear regime and experimentally demonstrate a far-field,label-free,and scan-free super-resolution imaging technique based on nonlinear four-wave mixing to retrieve near-field scattered evanescent waves,achieving a sub-wavelength resolution ofλ∕5.6.This method paves the way for numerous new applications in biomedical imaging,semiconductor metrology,and photolithography.展开更多
基金Supported by the National Natural Science Foundation of China(No.82171073No.82101147).
文摘●Multiple evanescent white dot syndrome(MEWDS)is a rare fundus disease,characterized by acute vision loss and visual field defects.Many previous studies have explained the possible pathogenesis and clinical features of primary MEWDS.However,as the number of reported cases increases,secondary MEWDS occurs in other related retinal diseases and injuries,exhibiting some special characteristics.The associated retinal diseases include multifocal choroiditis/punctate inner choroidopathy(MFC/PIC),acute zonal occult outer retinopathy,best vitelliform macular dystrophy,pseudoxanthoma elasticum,and ocular toxoplasmosis.The related retinal injury is laser photocoagulation,surgery,and trauma.Although primary MEWDS often have a self-limiting course,secondary MEWDS may require treatment in some cases,according to the severity of concomitant diseases and complications.Notably,MEWDS secondary to MFC/PIC that is prone to forming choroidal neovascularization and focal choroidal excavation,needs positive treatment with corticosteroids.The possible underlying pathogenesis of secondary MEWDS is the exposure of choroidal antigen after the disruption of Bruch’s membrane.The MEWDS-related features in secondary MEWDS are still evanescent under most circumstances.Its prognosis and treatment depend on the severity of complications.Current studies propose that the etiology is associated with immune factors,including viral infection,inflammation in choroid and Bruch’s membrane,and antigen exposure caused by retinal and/or choroidal insults.More pathogenic studies should be conducted in the future.Accurate diagnosis for secondary MEWDS could benefit patients in aspects of management and prognosis.
文摘Using a nanoscale silica fiber taper,light can be efficiently coupled into a single ZnO nanowire by means of evanescent coupling. The method is valid for launching light into a single nanowire in the ultraviolet to infrared range with a coupling efficiency of 25%, Low-loss optical guiding of ZnO nanowires is demonstrated, and the photoluminescence of a single ZnO nanowire is also observed. Compared to conventional approaches in which a lensfocused laser beam is used to excite nanowires at specific wavelengths,this evanescent coupling approach has advantages such as high coupling efficiency and broad-band validity, and it is promising for the optical characterization of semiconductor nanowires or nanoribbons.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60877037 and 10564005)
文摘A novel Whispering-Gallery-Mode （WGM） fibre laser, emitting linearly polarised three-colour light, is demonstrated by pumping and gain coupling with evanescent waves. The pump light is longitudinally coupled into a bare optical fibre immersed in a dye solution of lower refractive index. The dye molecules around the bare fibre are excited by the evanescent waves of pump light when they propagate along the fibre in a total internal reflection. When the pump beam within the fibre is a meridian beam, the WGM lasing emission from the fibre laser is a linearly polarised transverse electric wave, while it is a mixed wave of the linearly polarised transverse electric and magnetic waves if the pump beam is a skew beam within the fibre. Because the excited molecules are located within the evanescent field of WGM, a good spatial overlap between the dye gain and the evanescent field leads to a high pumping efficiency and a longer gain distance along the fibre. Once the bare fibre is inserted into three glass capillaries filled with Rhodamine 6G, 610 and 640 dye solutions, respectively, WGM laser oscillations at the wavelengths of 567-575, 605-614 and 656-666 nm occur simultaneously, and a linearly polarised three-colour lasing emission is achieved in a single optical fibre.
基金Project supported by the High Technology Research and Development Program of China (Grant Nos.2012AA012202 and 2013AA031401)the National Basic Research Program of China (Grant No.2012CB933503)the National Natural Science Foundation of China (Grant Nos.61176053,61274069,and 61021003)
文摘In this paper, we present the design, fabrication, and measurement of an evanescently coupled waveguide photode- tector operating at 1.55 gm, which mainly comprises a diluted waveguide, a single-mode rib waveguide and a p-i-n photodiode with an extended optical matching layer. The optical characteristics of this structure are studied by using a three-dimensional finite-difference time-domain （3D FDTD） method. The photodetector exhibits a high 3-dB bandwidth of more than 35 GHz and a responsivity of 0.291 A/W at 1550 nm directly coupled with a cleaved fiber. Moreover, a linear response of more than 72-mW optical power is achieved, where a photocurrent of more than 21 mA is obtained at a reverse bias voltage of 3 V.
文摘Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with fluorescein angiography （FA） and electrophysiology suggested that MEWDS to be a disease in the retinal pigment epithelium （RPE） or outer retina, while recent studies with spectral- domain optical coherence tomography （SD-OCT） suggested it may be an outer retinal disease due to observation of hyperreflective material in outer retina and subtle disruptionsof the ellipsoid zone without RPE disruption.
文摘To improve the sensitivity of protein microarray, a prism surface replaces the surface of the common microscope slide.The protein targets arrayed on the surface are hybridized and labelled by fluorescent probes. Evanescent excitation occurs when the convergent laser reaches the surface, and a photomultiplier tube detects the emitted fluorescent signal. A two-dimensional actuator scans the whole surface to achieve planar laser excitation and fluorescence collection. The penetration depth of the evanescent field into the protein targets is only some hundred nanometers and can be controlled by different incident angle of the laser beam, so the undesired background signals are reduced dramatically and the detection sensitivity is improved by a factor of 50 to 100 comparing to confocal excitation. This approach can detect low abundance analytes without signal amplification.
基金Project supported by the National High Technology Research and Development Program of China (Grant No 2006CB302802)
文摘We have studied the optical matching layers （OMLs） and external quantum efficiency in the evanescent coupling photodiodes （ECPDs） integrating a diluted waveguide as a fibre-to-waveguide coupler, by using the semi-vectorial beam propagation method （BPM）. The physical basis of OML has been identified, thereby a general designing rule of OML is developed in such a kind of photodiode. In addition, the external quantum efficiency and the polarization sensitivity versus the absorption and coupling length are analysed. With an optical matching layer, the absorption medium with a length of 30μm could absorb 90% of the incident light at 1.55μm wavelength, thus the total absorption increases more than 7 times over that of the photodiode without any optical matching layer.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2006CB302802)
文摘In this paper, we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency. High responsivity （〉 1 A/W）, high saturation power （〉 45 mA） in the static state and extremely low dark current density （0.04 pA/μm2） with 3 dB bandwidth at 13.4 GHz have been achieved.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10434080 and 60578018）, the National Basic Research Program of China （Grant No 2006CB921102） and also by the CFKSTIP （705010） and PCSIRT （IRT0516） from MEC.
文摘The bi-dimensional optical lattices formed by several sets of laser evanescent standing waves propagating at the surface of a dielectric prism are investigated. The characteristics of the optical traps including their depths and the sizes are analysed. It is shown that the micro-optical lattice with a sub-half-wavelength size can be achieved by the interference of the selected evanescent waves. The scheme together with the recently developed atomic chip may be used for atomic quantum manipulation.
文摘A discrete model of the Differential Evanescent Light Intensity (DELI) technique was developed to calculate and map 3D nanolayers thicknesses from the evanescent light intensity captured from optical waveguides. The model was used for ultra-thin Pd nanometric layers sputtered on glass substrates. The layers thickness profiles were displayed in 3D and 1D profiles plots. The total thickness profiles of the ultra-thin Pd films obtained in the range of 1-10 nm were validated using AFM measurements. Based on the model developed the evanescent photon extraction parameter of the material was estimated.
文摘To report the case of a patient who presented with idiopathic choroidal neovascularization(CNV)as the first sign of multiple evanescent white dot syndrome(MEWDS).A 25-year-old woman presented with recent onset of decreased vision and metamorphopsia in the right eye.The results of fundoscopic examination,fluorescein angiography,and optical coherence tomography(OCT) were compatible with a diagnosis of idiopathic CNV,which was treated with one intravitreal injection of bevacizumab.Five years later,the patient returned complaining of photopsia and decreased vision in the same eye.The fundoscopic examination showed typical signs of MEWDS.After 3 months,recurrence of CNV was observed in the same eye.In conclusion,idiopathic CNV might be the only manifestation of a subclinical occurrence of MEWDS.In this case,it was followed by a recurrence of MEWDS and subsequent reactivation of CNV.
文摘A portable evanescent wave optic ?ber immunosensor was developed for detection of 2,4-dichlorophenoxyacetic acid(2,4-D) using a indirect competitive immunoassay. In this paper, hapten conjugates 2,4-D-OVA were immobilized with covalent binding methods. After pre-reacting, 2,4-D-antibody-Cy5.5 in sample specifically recognized the 2,4-D antigens binding sites on surface of the optical fiber probe. Under optimum conditions, 2,4-D could be detected in less than 18 min for each assay cycle. The regeneration of the optic ?ber surface allowed more than 200 times without losing performance. The limits of detection of 0.039 ug/L and the quantitative detection range of 0.47 - 81.02 ug/L were obtained when the concentration of 2,4-D was 1 mg/L. This immunosensor shows great potential in rapid simultaneous detection of 2,4-D in waters samples.
基金Supported by the High-Tech Research and Development Program of China under Grant Nos 2013AA031401,2015AA016902 and 2015AA016904the National Natural Science Foundation of China under Grant Nos 61176053,61274069 and 61435002the National Basic Research Program of China under Grant No 2012CB933503
文摘We design and fabricate a parallel system with 10 high speed side-illuminated evanescently coupled waveguide photodetectors （ECPDs）. The 10 ECPDs exhibit a uniform 3dB bandwidth of 20 GHz and low dark current of about i nA at 2 V reverse bias. The 10 ECPDs also exhibit uniform photo-responsivity of about 0.23A/W with an active region of 5 × 25μmS. The photodetector array has a total bandwidth of more than 200 GHz and can be integrated with other optoelectronic devices.
文摘It is pointed out that the evanescent light wave occurring at total reflection does not possess a transverse spin angular momentum as Bliokh, Bekshaev, and Nori claimed recently in (2014) Nature Communications, 5,3300. This is not only because of the nonlocality of the photon spin but also because the evanescent wave is such a state whose angular momentum cannot be separated into spin and orbital parts.
文摘Nanometric profiles of sputtered ultra-thin Pd layers with thicknesses in the range 1 - 10 nm were investigated by capturing the leaking evanescent light from optical waveguides. The Pd films were deposited by sputtering on glass substratesalso servingas light waveguides. Calibrating the thickness values for the ultra-thin Pd films obtained from the sputtering rate combined with the DELI estimation technique, gave detailed 1Dand 3D morphological nanometric profiles of the deposited layers.
文摘Usually, electromagnetic evanescent waves are some kinds of near fields. However, it looks as if the evanescent waves inside a cut-off waveguide had nothing to do with any near field. In this paper, we will show that the evanescent waves inside a cut-off waveguide can also be regarded as the near fields of an aerial array.
基金This work was supported in part by the Guangdong Major Project of Basic and Applied Basic Research[grant number 2020B0301030009]the National Natural Science Foundation of China(NSFC)[grant numbers 62175159,62175157,12174204,62071306]+3 种基金the Natural Science Foundation of Guangdong Province,Guangdong,China[2023A1515012888]the Science and Technology Innovation Commission of Shenzhen[grant numbers KQTD20170330110444030,JCYJ20200109113808048,RCJC20210609103232046,JCYJ20200109113601723,JSGG20210802154203011,JSGG20210420091805014,JCYJ20220818101417039]Key Research Project of Zhejiang Lab:K2022MG0AC05China Postdoctoral Science Foundation:2022M722174.
文摘In addition to offering morphological visualizations via capture of the spatial distributions of optical absorption,photoacoustic imaging technology can reveal abundant physical information about biological particles,including their orientation,density,and viscoelasticity,through analysis of the pressure transients in the spectral domain.However,the low-amplitude wideband photoacoustic signals of intrinsic microscopic optically-absorbing objects under the action of confined photoacoustic excitation power continue to hinder simultaneous photoacoustic structural imaging and spectroscopic analysis of the nonfluorescent chromophores in living biological tissues because of the inadequate responses to photoacoustic impulses observed in most photoacoustic imaging setups that include piezoelectric transducers.Building upon a recently-developed optical evanescent wave sensor that can respond to ultrasound with high sensitivity over a broad frequency range,we propose in vivo spatial-spectral photoacoustic microscopy for recovery of structural imaging in three dimensions and characterization of anatomical features in the acoustic frequency domain.Label-free photoacoustic images of a living zebrafish are acquired in which spectroscopically-resolved differentiation of the microarchitecture is accessed,along with isometric micrometer-scale volumetric visualizations.The proposed imaging technology could potentially provide more comprehensive evaluations of the physiopathological status of living small animals.
基金Supported by the National Natural Science Foundation of China(NSFC)(61904183,61974152,62104237,62004205)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y202057)+1 种基金Shanghai Science and Technology Committee Rising-Star Program(20QA1410500)Shanghai Sail Plans(21YF1455000)。
文摘In the realm of near-infrared spectroscopy,the detection of molecules has been achieved using on-chip waveguides and resonators.In the mid-infrared band,the integration and sensitivity of chemical sensing chips are often constrained by the reliance on off-chip light sources and detectors.In this study,we demonstrate an InAs/GaAsSb superlattice mid-infrared waveguide integrated detector.The GaAsSb waveguide layer and the InAs/GaAsSb superlattice absorbing layer are connected through evanescent coupling,facilitating efficient and highquality detection of mid-infrared light with minimal loss.We conducted a simulation to analyze the photoelectric characteristics of the device.Additionally,we investigated the factors that affect the integration of the InAs/GaAs⁃Sb superlattice photodetector and the GaAsSb waveguide.Optimal thicknesses and lengths for the absorption lay⁃er are determined.When the absorption layer has a thickness of 0.3μm and a length of 50μm,the noise equiva⁃lent power reaches its minimum value,and the quantum efficiency can achieve a value of 68.9%.The utilization of waveguide detectors constructed with Ⅲ-Ⅴ materials offers a more convenient means of integrating mid-infra⁃red light sources and achieving photoelectric detection chips.
基金This work was funded by the Fund of Shanxi“1331”Project Key Subject ConstructionNational Science Foundation of Shanxi Province,China(Grant No.20170ID 121065)。
文摘A novel high sensitivity relative humidity(RH)sensor was proposed by using micro structure plastic optical fiber(POF)based on the surface plasmon resonance(SPR)effect and the evanescent wave(EW)loss.The micro structure was fabricated on the POF and coated with a gold layer and agarose,adopting the sputtering and dip-coating technique.These construction effects on the attenuation of power caused by the SPR effect and the EW loss were used to perform RH detections.The agarose9s different refractive indexes(RIs)caused fluctuations in the transmission power when the humidity increased.The demonstrated experimental results showed that the proposed sensor achieved a linear response from 20%RH to 80%RH with a high sensitivity of 0.595μW/%.The proposed sensor had the advantages of fast response and recovery.Furthermore,the temperature dependence and the repeatability test of the sensor were also performed.
基金This work was supported by the National Key Research and Development Program(Grant Nos.2016YFA0302500 and 2017YFA0303700)National Natural Science Foundation of China(Grant Nos.92050113 and 11674228)Shanghai MEC Scientific Innovation Program(Grant No.E00075).
文摘Abbe’s resolution limit,one of the best-known physical limitations,poses a great challenge for any wave system in imaging,wave transport,and dynamics.Originally formulated in linear optics,the Abbe limit can be broken using nonlinear optical interactions.We extend the Abbe theory into a nonlinear regime and experimentally demonstrate a far-field,label-free,and scan-free super-resolution imaging technique based on nonlinear four-wave mixing to retrieve near-field scattered evanescent waves,achieving a sub-wavelength resolution ofλ∕5.6.This method paves the way for numerous new applications in biomedical imaging,semiconductor metrology,and photolithography.
