Detection of small cancer biomarkers with low molecular weight and a low concentration range has always been challenging yet urgent in many clinical applications such as diagnosing early-stage cancer,monitoring treatm...Detection of small cancer biomarkers with low molecular weight and a low concentration range has always been challenging yet urgent in many clinical applications such as diagnosing early-stage cancer,monitoring treatment and detecting relapse.Here,a highly enhanced plasmonic biosensor that can overcome this challenge is developed using atomically thin two-dimensional phase change nanomaterial.By precisely engineering the configuration with atomically thin materials,the phase singularity has been successfully achieved with a significantly enhanced lateral position shift effect.Based on our knowledge,it is the first experimental demonstration of a lateral position signal change>340μm at a sensing interface from all optical techniques.With this enhanced plasmonic effect,the detection limit has been experimentally demonstrated to be 10^(-15) mol L^(−1) for TNF-α cancer marker,which has been found in various human diseases including inflammatory diseases and different kinds of cancer.The as-reported novel integration of atomically thin Ge_(2)Sb_(2)Te_(5) with plasmonic substrate, which results in a phase singularity and thus a giant lateral position shift, enables the detection of cancer markers with low molecular weight at femtomolar level. These results will definitely hold promising potential in biomedical application and clinical diagnostics.展开更多
Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and str...Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and strong evanescent field. All these properties of WGM microresonators have ensured their great potentials for applications, such as physical sen- sors, bio/chemical sensors and microlasers. In this mini-review, the key parameters and coupling conditions of WGM microresonators are firstly introduced. The geometries of WGM optical microcavities are presented based on their fabri- cation methods. This is followed by the discussion on the state-of-the-art applications of WGM microresonators in sen- sors and microlasers.展开更多
We review the use of hollow-core photonic crystal fibre(HC-PCF)for high power laser beam delivery.A comparison of bandgap HC-PCF with Kagome-lattice HC-PCF on the geometry,guidance mechanism,and optical properties sho...We review the use of hollow-core photonic crystal fibre(HC-PCF)for high power laser beam delivery.A comparison of bandgap HC-PCF with Kagome-lattice HC-PCF on the geometry,guidance mechanism,and optical properties shows that the Kagome-type HC-PCF is an ideal host for high power laser beam transportation because of its large core size,low attenuation,broadband transmission,single-mode guidance,low dispersion and the ultra-low optical overlap between the core-guided modes and the silica core-surround.The power handling capability of Kagome-type HC-PCF is further experimentally demonstrated by millijoule nanosecond laser spark ignition and^100μJ sub-picosecond laser pulse transportation and compression.展开更多
Rapid plasmonic biosensing has attracted wide attention in early disease diagnosis and molecular biology research.However,it was still challenging for conventional angle-interrogating plasmonic sensors to obtain highe...Rapid plasmonic biosensing has attracted wide attention in early disease diagnosis and molecular biology research.However,it was still challenging for conventional angle-interrogating plasmonic sensors to obtain higher sensitivity without secondary amplifying labels such as plasmonic nanoparticles.To address this issue,we developed a plasmonic biosensor based on the enhanced lateral position shift by phase singularity.Such singularity presents as a sudden phase retardation at the dark point of reflection from resonating plasmonic substrate,leading to a giant position shift on reflected beam.Herein,for the first time,the atomically thin layer of Ge2Sb2Te5(GST)on silver nanofilm was demonstrated as a novel phase-response-enhancing plasmonic material.The GST layer was not only precisely engineered to singularize phase change but also served as a protective layer for active silver nanofilm.This new configuration has achieved a record-breaking largest position shift of 439.3μm measured in calibration experiments with an ultra-high sensitivity of 1.72×10^(8)nm RIU−1(refractive index unit).The detection limit was determined to be 6.97×10^(−7)RIU with a 0.12μm position resolution.Besides,a large figure of merit(FOM)of 4.54×10^(11)μm(RIU∙°)^(−1)was evaluated for such position shift interrogation,enabling the labelfree detection of trace amounts of biomolecules.In targeted biosensing experiments,the optimized sensor has successfully detected small cytokine biomarkers(TNF-αand IL-6)with the lowest concentration of 1×10^(−16)M.These two molecules are the key proinflammatory cancer markers in clinical diagnosis,which cannot be directly screened by current clinical techniques.To further validate the selectivity of our sensing systems,we also measured the affinity of integrin binding to arginylglycylaspartic acid(RGD)peptide(a key protein interaction in cell adhesion)with different Mn2+ion concentrations,ranging from 1 nM to 1 mM.展开更多
The high-energy few-cycle mid-infrared laser pulse beyond 2μm is of immense importance for attosecond science and strong-field physics.However,the limited gain bandwidth of laser crystals such as Ho:YLF and Ho:YAG al...The high-energy few-cycle mid-infrared laser pulse beyond 2μm is of immense importance for attosecond science and strong-field physics.However,the limited gain bandwidth of laser crystals such as Ho:YLF and Ho:YAG allows the generation of picosecond(ps)long pulses and,hence,makes it challenging to generate few-cycle pulse at 2μm without utilizing an optical parametric chirped-pulse amplifier(OPCPA).Moreover,the exclusive use of the near-infrared wavelength has limited the generation of wavelengths beyond 4μm(OPCPA).Furthermore,high harmonic generation(HHG)conversion efficiency reduces dramatically when driven by a long-wavelength laser.Novel schemes such as multi-color HHG have been proposed to enhance the harmonic flux.Therefore,it is highly desirable to generate few-cycle to femtosecond pulses from a 2μm laser for driving these experiments.Here,we utilize two-stage nonlinear spectral broadening and pulse compression based on the Kagome-type hollow-core photonic crystal fiber(HC-PCF)to compress few-ps pulses to sub-50 fs from a Ho:YLF amplifier at 2μm at 1 kHz repetition rate.We demonstrate both experimentally and numerically the compression of 3.3 ps at 140μJ pulses to 48 fs at 11μJ with focal intensity reaching 10^(13)W/cm^(20.Thereby,this system can be used for driving HHG in solids at 2μm.In the first stage,the pulses are spectrally broadened in Kagome fiber and compressed in a silicon-based prism compressor to 285 fs at a pulse energy of 90μJ.In the second stage,the 285 fs pulse is self-compressed in air-filled HC-PCF.With fine-tuning of the group delay dispersion(GDD)externally in a 3 mm window,a compressed pulse of 48 fs is achieved.This leads to a 70-fold compression of the ps pulses at 2050 nm.We further used the sub-50 fs laser pulses to generate white light by focusing the pulse into a thin medium of YAG.展开更多
Historically, nonlinear optical phenomena such as spectral broadening by harmonic generation have been associated with crystals owing to their strong nonlinear refractive indices, which are in the range of 10-14cm^2∕...Historically, nonlinear optical phenomena such as spectral broadening by harmonic generation have been associated with crystals owing to their strong nonlinear refractive indices, which are in the range of 10-14cm^2∕W.This association was also the result of the limited optical power available from early lasers and the limited interaction length that the laser–crystal interaction architecture could offer. Consequently, these limitations disqualified a large number of materials whose nonlinear coefficient is lower than n210-16cm^2∕W as suitable materials for nonlinear optics applications. For example, it is a common practice in most of optical laboratories to consider ambient or atmospheric air as a "nonlinear optically" inert medium due to its very low nonlinear coefficient(10.10^-19cm^2∕W) and low density. Today, the wide spread of high-power ultra-short pulse lasers on one hand, and low transmission loss and high-power handling of Kagome hollow-core photonic crystal fiber on the other hand, provide the necessary ingredients to excite strong nonlinear optical effects in practically any gas media, regardless of how low its optical nonlinear response is. By using a single table-top 1 m J ultra-short pulse laser and an air exposed inhibited-coupling guiding hollow-core photonic crystal fiber, we observed generation of supercontinuum and third harmonic generation when the laser pulse duration was set at 600 fs and Raman comb generation when the duration was 300 ps. The supercontinuum spectrum spans over 1000 THz and exhibits a typical spectral-density energy of 150 n J/nm. The dispersion profile of inhibited-coupling hollow-core fiber imprints a distinctive sequence in the supercontinuum generation, which is triggered by the generation of a cascade of four-wave mixing lines and concluded by solitonic dynamics. The Raman comb spans over 300 THz and exhibits multiple sidebands originating from N2 vibrational and ro-vibrational Raman transitions. With the growing use of hollow-core photonic crystal fiber in different fields, the results can be applied to mitigate air nonlinear response when it is not desired or to use ambient air as a convenient nonlinear medium.展开更多
Propagation of light in multimode optical fibers usually gives a spatial and temporal randomization of the transmitted field similar to the propagation through scattering media.Randomization still applies when scatter...Propagation of light in multimode optical fibers usually gives a spatial and temporal randomization of the transmitted field similar to the propagation through scattering media.Randomization still applies when scattering or multimode propagation occurs in gain media.We demonstrate that appropriate structuration of the input beam wavefront can shape the light amplified by a rareearth-doped multimode fiber.Profiling of the wavefront was achieved by a deformable mirror in combination with an iterative optimization process.We present experimental results and simulations showing the shaping of a single sharp spot at different places in the output cross-section of an ytterbium-doped fiber amplifier.Cleaning and narrowing of the amplifier far-field pattern was realized as well.Tailoring the wavefront to shape the amplified light can also serve to improve the effective gain.The shaping approach still works under gain saturation,showing the robustness of the method.Modeling and experiments attest that the shaping is effective even with a highly multimode fiber amplifier carrying up to 127 modes.展开更多
基金We thank Shiyue Liu from School of Life Sciences in The Chinese University of Hong Kong for helpful discussions.This work is supported under the PROCORE-France/Hong Kong Joint Research Scheme(F-CUHK402/19)the Research Grants Council,Hong Kong Special Administration Region(AoE/P-02/12,14210517,14207419,N_CUHK407/16)the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No.798916.Y.Wang is supported under the Hong Kong PhD Fellowship Scheme.
文摘Detection of small cancer biomarkers with low molecular weight and a low concentration range has always been challenging yet urgent in many clinical applications such as diagnosing early-stage cancer,monitoring treatment and detecting relapse.Here,a highly enhanced plasmonic biosensor that can overcome this challenge is developed using atomically thin two-dimensional phase change nanomaterial.By precisely engineering the configuration with atomically thin materials,the phase singularity has been successfully achieved with a significantly enhanced lateral position shift effect.Based on our knowledge,it is the first experimental demonstration of a lateral position signal change>340μm at a sensing interface from all optical techniques.With this enhanced plasmonic effect,the detection limit has been experimentally demonstrated to be 10^(-15) mol L^(−1) for TNF-α cancer marker,which has been found in various human diseases including inflammatory diseases and different kinds of cancer.The as-reported novel integration of atomically thin Ge_(2)Sb_(2)Te_(5) with plasmonic substrate, which results in a phase singularity and thus a giant lateral position shift, enables the detection of cancer markers with low molecular weight at femtomolar level. These results will definitely hold promising potential in biomedical application and clinical diagnostics.
基金This work is partially supported by National Natural Science Foundation of China （11774102）, the Scientific Research Funds and Promotion Program for Young and Middle-aged Teacher in Science ＆ Technology Research of Huaqiao University （ZQN-YXS04, 17BS412）, Open Fund of IPOC （BUPT）, National Research Foundation Singapore （NRF） （NRF-CRP13-2014-05）, European Union＇s Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement （No. 798916） and Singapore Ministry of Education Academic Research Fund Tier 1 （RG89/16）.
文摘Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and strong evanescent field. All these properties of WGM microresonators have ensured their great potentials for applications, such as physical sen- sors, bio/chemical sensors and microlasers. In this mini-review, the key parameters and coupling conditions of WGM microresonators are firstly introduced. The geometries of WGM optical microcavities are presented based on their fabri- cation methods. This is followed by the discussion on the state-of-the-art applications of WGM microresonators in sen- sors and microlasers.
文摘We review the use of hollow-core photonic crystal fibre(HC-PCF)for high power laser beam delivery.A comparison of bandgap HC-PCF with Kagome-lattice HC-PCF on the geometry,guidance mechanism,and optical properties shows that the Kagome-type HC-PCF is an ideal host for high power laser beam transportation because of its large core size,low attenuation,broadband transmission,single-mode guidance,low dispersion and the ultra-low optical overlap between the core-guided modes and the silica core-surround.The power handling capability of Kagome-type HC-PCF is further experimentally demonstrated by millijoule nanosecond laser spark ignition and^100μJ sub-picosecond laser pulse transportation and compression.
基金the UTT Project Stratégique NanoSPR(OPE-2022-0293)the Graduate School(Ecole Universitaire de Recherche)“NANOPHOT”(ANR-18-EURE-0013)+1 种基金PHC PROCORE-Campus France/Hong Kong Joint Research Scheme(No.44683Q)AAP1-LABEX SigmaPIX 2021.
文摘Rapid plasmonic biosensing has attracted wide attention in early disease diagnosis and molecular biology research.However,it was still challenging for conventional angle-interrogating plasmonic sensors to obtain higher sensitivity without secondary amplifying labels such as plasmonic nanoparticles.To address this issue,we developed a plasmonic biosensor based on the enhanced lateral position shift by phase singularity.Such singularity presents as a sudden phase retardation at the dark point of reflection from resonating plasmonic substrate,leading to a giant position shift on reflected beam.Herein,for the first time,the atomically thin layer of Ge2Sb2Te5(GST)on silver nanofilm was demonstrated as a novel phase-response-enhancing plasmonic material.The GST layer was not only precisely engineered to singularize phase change but also served as a protective layer for active silver nanofilm.This new configuration has achieved a record-breaking largest position shift of 439.3μm measured in calibration experiments with an ultra-high sensitivity of 1.72×10^(8)nm RIU−1(refractive index unit).The detection limit was determined to be 6.97×10^(−7)RIU with a 0.12μm position resolution.Besides,a large figure of merit(FOM)of 4.54×10^(11)μm(RIU∙°)^(−1)was evaluated for such position shift interrogation,enabling the labelfree detection of trace amounts of biomolecules.In targeted biosensing experiments,the optimized sensor has successfully detected small cytokine biomarkers(TNF-αand IL-6)with the lowest concentration of 1×10^(−16)M.These two molecules are the key proinflammatory cancer markers in clinical diagnosis,which cannot be directly screened by current clinical techniques.To further validate the selectivity of our sensing systems,we also measured the affinity of integrin binding to arginylglycylaspartic acid(RGD)peptide(a key protein interaction in cell adhesion)with different Mn2+ion concentrations,ranging from 1 nM to 1 mM.
基金European Research Council(609920)Hamburg Centre for Ultrafast Imaging+3 种基金Deutsche ForschungsgemeinschaftGordon and Betty Moore FoundationAgence Nationale de la RechercheConseil Regional du Limousin.
文摘The high-energy few-cycle mid-infrared laser pulse beyond 2μm is of immense importance for attosecond science and strong-field physics.However,the limited gain bandwidth of laser crystals such as Ho:YLF and Ho:YAG allows the generation of picosecond(ps)long pulses and,hence,makes it challenging to generate few-cycle pulse at 2μm without utilizing an optical parametric chirped-pulse amplifier(OPCPA).Moreover,the exclusive use of the near-infrared wavelength has limited the generation of wavelengths beyond 4μm(OPCPA).Furthermore,high harmonic generation(HHG)conversion efficiency reduces dramatically when driven by a long-wavelength laser.Novel schemes such as multi-color HHG have been proposed to enhance the harmonic flux.Therefore,it is highly desirable to generate few-cycle to femtosecond pulses from a 2μm laser for driving these experiments.Here,we utilize two-stage nonlinear spectral broadening and pulse compression based on the Kagome-type hollow-core photonic crystal fiber(HC-PCF)to compress few-ps pulses to sub-50 fs from a Ho:YLF amplifier at 2μm at 1 kHz repetition rate.We demonstrate both experimentally and numerically the compression of 3.3 ps at 140μJ pulses to 48 fs at 11μJ with focal intensity reaching 10^(13)W/cm^(20.Thereby,this system can be used for driving HHG in solids at 2μm.In the first stage,the pulses are spectrally broadened in Kagome fiber and compressed in a silicon-based prism compressor to 285 fs at a pulse energy of 90μJ.In the second stage,the 285 fs pulse is self-compressed in air-filled HC-PCF.With fine-tuning of the group delay dispersion(GDD)externally in a 3 mm window,a compressed pulse of 48 fs is achieved.This leads to a 70-fold compression of the ps pulses at 2050 nm.We further used the sub-50 fs laser pulses to generate white light by focusing the pulse into a thin medium of YAG.
基金BPI via PIA-4F projectAgence Nationale de la Recherche(ANR)(PhotoSynth,Labex SigmaLim,UVfactor)+1 种基金Région Nouvelle Aquitaine,Air Force Office of Scientific Research(AFOSR)(FA9+550-14-1-0024)National Science Formation(NSF)(PHY-1068865).
文摘Historically, nonlinear optical phenomena such as spectral broadening by harmonic generation have been associated with crystals owing to their strong nonlinear refractive indices, which are in the range of 10-14cm^2∕W.This association was also the result of the limited optical power available from early lasers and the limited interaction length that the laser–crystal interaction architecture could offer. Consequently, these limitations disqualified a large number of materials whose nonlinear coefficient is lower than n210-16cm^2∕W as suitable materials for nonlinear optics applications. For example, it is a common practice in most of optical laboratories to consider ambient or atmospheric air as a "nonlinear optically" inert medium due to its very low nonlinear coefficient(10.10^-19cm^2∕W) and low density. Today, the wide spread of high-power ultra-short pulse lasers on one hand, and low transmission loss and high-power handling of Kagome hollow-core photonic crystal fiber on the other hand, provide the necessary ingredients to excite strong nonlinear optical effects in practically any gas media, regardless of how low its optical nonlinear response is. By using a single table-top 1 m J ultra-short pulse laser and an air exposed inhibited-coupling guiding hollow-core photonic crystal fiber, we observed generation of supercontinuum and third harmonic generation when the laser pulse duration was set at 600 fs and Raman comb generation when the duration was 300 ps. The supercontinuum spectrum spans over 1000 THz and exhibits a typical spectral-density energy of 150 n J/nm. The dispersion profile of inhibited-coupling hollow-core fiber imprints a distinctive sequence in the supercontinuum generation, which is triggered by the generation of a cascade of four-wave mixing lines and concluded by solitonic dynamics. The Raman comb spans over 300 THz and exhibits multiple sidebands originating from N2 vibrational and ro-vibrational Raman transitions. With the growing use of hollow-core photonic crystal fiber in different fields, the results can be applied to mitigate air nonlinear response when it is not desired or to use ambient air as a convenient nonlinear medium.
基金funding from the French Agence Nationale de la Recherche in the frame of the POMAD project(14-CE26-0035-01)。
文摘Propagation of light in multimode optical fibers usually gives a spatial and temporal randomization of the transmitted field similar to the propagation through scattering media.Randomization still applies when scattering or multimode propagation occurs in gain media.We demonstrate that appropriate structuration of the input beam wavefront can shape the light amplified by a rareearth-doped multimode fiber.Profiling of the wavefront was achieved by a deformable mirror in combination with an iterative optimization process.We present experimental results and simulations showing the shaping of a single sharp spot at different places in the output cross-section of an ytterbium-doped fiber amplifier.Cleaning and narrowing of the amplifier far-field pattern was realized as well.Tailoring the wavefront to shape the amplified light can also serve to improve the effective gain.The shaping approach still works under gain saturation,showing the robustness of the method.Modeling and experiments attest that the shaping is effective even with a highly multimode fiber amplifier carrying up to 127 modes.
