We show that electric field on the plane surface of truncated sphere or cylinders(so called Janus particles)have sharp resonances versus the depth of removed segment of a sphere or cylinder.These resonances are relate...We show that electric field on the plane surface of truncated sphere or cylinders(so called Janus particles)have sharp resonances versus the depth of removed segment of a sphere or cylinder.These resonances are related to the excited whispering gallery waves caused by truncation.It is a new mechanism of the field localization.Optimization of this effect for cylinders permits to reach a super resolution in the line thickness,which can be used for contact optical lithography.展开更多
During the last decades the whispering gallery mode based sensors have become a prominent solution for label-free sensing of various physical and chemical parameters.At the same time,the widespread utilization of the ...During the last decades the whispering gallery mode based sensors have become a prominent solution for label-free sensing of various physical and chemical parameters.At the same time,the widespread utilization of the approach is hindered by the restricted applicability of the known configurations for ambient variations quantification outside the laboratory conditions and their low affordability,where necessity on the spectrally-resolved data collection is among the main limiting factors.In this paper we demonstrate the first realization of an affordable whispering gallery mode sensor powered by deep learning and multi-resonator imaging at a fixed frequency.It has been shown that the approach enables refractive index unit(RIU)prediction with an absolute error at 3×10^(-6) level for dynamic range of the RIU variations from 0 to 2×10^(-3) with temporal resolution of several milliseconds and instrument-driven detection limit of 3×10−5.High sensing accuracy together with instrumental affordability and production simplicity places the reported detector among the most cost-effective realizations of the whispering gallery mode approach.The proposed solution is expected to have a great impact on the shift of the whole sensing paradigm away from the model-based and to the flexible self-learning solutions.展开更多
We investigate theoretically the single-photon scattering by a A-type three-level system interacting with a whispering-gallery-type resonator which is coupled to a one-dimensional waveguide by full quantum-mechanical ...We investigate theoretically the single-photon scattering by a A-type three-level system interacting with a whispering-gallery-type resonator which is coupled to a one-dimensional waveguide by full quantum-mechanical approach. The single-photon transmission amplitude and reflection amplitude are obtained exactly via real-space approach. The single-photon transport properties controlling by classic optical field are discussed. The critical coupling condition in the coupled waveguide-whispering-gallery resonator-atom with three-level system is also analyzed.展开更多
The III-nitride semiconductor microdisk laser exhibits high quality factor and low excitation threshold with broad development potential in the field of nanophotonics such as nanoscale light-emitting devices and on-ch...The III-nitride semiconductor microdisk laser exhibits high quality factor and low excitation threshold with broad development potential in the field of nanophotonics such as nanoscale light-emitting devices and on-chip optical integration.So far,many works have been focused on process synthesis and nanostructural design of microdisk lasers.Nevertheless,there are still some limitations in the existing optical resonance mode which is an important internal influence factor for lasing characteristics.In this work,a new double-triangular whispering-gallery mode(D3-WGM)lasing from a hexagonal GaN microdisk with a high quality(Q)factor of 3049 and an excitation threshold of around 11.5μW has been experimentally demonstrated.In addition,the optical properties of hexagonal-WGM(6-WGM),triangular-WGM(3-WGM)and D3-WGM lasing from microdisk are explored by numerical calculation and Comsol simulation.These results confirm that the D3-WGM lasing has its own significant performance advantages,namely high Q factor and easy light emission.Based on this novel laser mode characteristic,microcavity lasers are expected to be further developed and applied in the field of nanophotonics.展开更多
A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode （WGM） resonance in bent optical fibers,is proposed. The sensor is composed of a single loop forme...A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode （WGM） resonance in bent optical fibers,is proposed. The sensor is composed of a single loop formed by loosely tying a knot using single mode fiber. To measure the transmission spectra, a tunable laser and an optic power meter are connected to the two ends of fi- ber loop, respectively. Significant WGM resonances occur over the investigated wavelength range for all the sensors with different bend radius. The angular-displacement sensitivity is studied in the range from -0. 1°to 0. 1°. The detection limit of 1.49 × 10 ^-7 rad can be achieved for the detecting system with the resolution of lpm. The simple loop-structure fiber sensor has potential application prospect in the field of architecture or bridge building with low detection limit and low cost.展开更多
In this letter,a humidity sensor is demonstrated by applying a whispering gallery mode(WGM)from a microsphere resonator onto the ZnO nanorods coated glass surface.The diameter of the microsphere was 234μm and the gla...In this letter,a humidity sensor is demonstrated by applying a whispering gallery mode(WGM)from a microsphere resonator onto the ZnO nanorods coated glass surface.The diameter of the microsphere was 234μm and the glass surface was coated with ZnO nanorods using the hydrothermal method at growth duration of 12 h.A significant response to humidity level ranging from 35%RH to 85%RH has been observed with the sensitivity of 0.0142 nm/%RH.The proposed humidity sensor has successfully employed to enhance interaction between the whispering gallery mode evanescent and surrounds analyte with the assistance of ZnO nanorods coated glass.展开更多
Lithium tetraborate(LB4)is a lithium borate compound known for its exceptional linear and nonlinear optical properties,including a wide transparency range(0.16–3.5μm)and high Raman gain.Here,a millimeter-sized LB4 w...Lithium tetraborate(LB4)is a lithium borate compound known for its exceptional linear and nonlinear optical properties,including a wide transparency range(0.16–3.5μm)and high Raman gain.Here,a millimeter-sized LB4 whispering gallery mode(WGM)resonator with a record quality factor of 2.0×10^(9) at 517 nm was fabricated using single-point diamond cutting.Pumped with about 10 m W at 517 nm,it demonstrated four cascaded stimulated Raman scattering(SRS)peaks(537–608 nm),with the first-order SRS achieving a threshold of 0.71 m W and 7.2% slope efficiency.To our knowledge,this marks the first LB4 WGM resonator Raman laser.展开更多
Upconversion nanoparticles(UCNPs)have attracted considerable interest due to their large anti-Stokes shift,offering promising applications in lasing.Here,multi-wavelength upconversion whispering gallery mode(WGM)lasin...Upconversion nanoparticles(UCNPs)have attracted considerable interest due to their large anti-Stokes shift,offering promising applications in lasing.Here,multi-wavelength upconversion whispering gallery mode(WGM)lasing is demonstrated in silica microspheres coated with NaYF_(4)@NaYbF_(4):1%Tm^(3+)@NaYF_(4)nanoparticles and coupled with tapered fibers.Under continuous-wave 980 nm pumping,low-threshold lasing is achieved across Tm3+transitions from near-infrared to visible,with an ultra-low threshold of 0.61μWfor the 3H_(4)→3H_(6)transition.Additionally,upconversion laser output can also be achieved in Er^(3+)-and Ho^(3+)-activated microspheres.These results establish tapered fiber coupling as a versatile approach for enhancing upconversion microlasers.展开更多
This paper investigates the use of artificial neural networks(ANNs)as a viable digital twin or alternative to the typical whispering gallery mode(WGM)optical sensors in engineering systems,especially in dynamic enviro...This paper investigates the use of artificial neural networks(ANNs)as a viable digital twin or alternative to the typical whispering gallery mode(WGM)optical sensors in engineering systems,especially in dynamic environments like robotics.Because of its fragility and limited endurance,the WGM sensor which is based on micro-optical resonators is inappropriate in these kinds of situations.In order to address these issues,the paper suggests an ANN that is specifically designed for the system and makes use of the WGM sensor’s high-quality factor(Q-factor).By extending the applicability and endurance to dynamic contexts and reducing fragility problems,the ANN seeks to give high-resolution measurement.In order to minimize post-processing requirements and maintain system robustness,the study goal is for the ANN to function as a representative predictor of the WGM sensor output.The GUCnoid 1.0 humanoid robot is used in the paper as an example to show how the WGM optical sensors may improve humanoid robot performance for a variety of applications.The results of the experiments demonstrate that the sensitivity,precision,and resolution of ANN outputs and actual WGM shifts are equivalent.As a consequence,current obstacles to the widespread use of high-precision sensing in the robotics industry are removed,and the potential of ANNs as virtual substitutes or the digital twin for genuine WGM sensors in robotics systems is validated.So,this paper can be very beneficial not only to the sensing technologies that are used in robotics,which are subjected to the dynamic environments,but also to the industrial automation and human-machine interface.展开更多
Whispering gallery mode resonators(WGMRs)are used as excellent optical feedback components of narrow-linewidth fiber lasers,applied from distributed fiber sensing to optical fiber communication.However,WGMRs lead to o...Whispering gallery mode resonators(WGMRs)are used as excellent optical feedback components of narrow-linewidth fiber lasers,applied from distributed fiber sensing to optical fiber communication.However,WGMRs lead to output of a few microwatts and serious multi-modes in lasers.In this Letter,we fabricated the specially designed WGMR with an overcoupling structure,and its quality(Q)factor was over 10^(9).It improved laser output power significantly.Based on that,dynamic population gratings were applied successfully in the laser.Finally,a single-frequency WGMR fiber laser was realized.Its linewidth was less than 1.07 kHz,its output power was over 0.107 mW,and its spectral signal-to-noise ratio(SNR)was nearly 50 dB.Our research offers a new scheme of a single-frequency narrow-linewidth WGMR fiber laser.展开更多
Whispering gallery modes (WGMs) were first discovered for sound waves in the whispering gallery of St Paul’s Cathedral and explained by Rayleigh [1] in 1878. In 1961, Garrett et al.[2] applied the concept of WGMs to ...Whispering gallery modes (WGMs) were first discovered for sound waves in the whispering gallery of St Paul’s Cathedral and explained by Rayleigh [1] in 1878. In 1961, Garrett et al.[2] applied the concept of WGMs to optical systems and realized stimulated emissions in Sm2+-doped CaF2 spheres.Since then, WGMs have been widely and intensively studied in a range of micro-sized systems, including microdroplets,microspheres, microtoroids, microdisks, and microtubes.展开更多
In this study, we investigate the fabrication of periodically poled lithium niobate(PPLN) microdisk cavities on a chip. These resonators are fabricated from a PPLN film with a 16 μm poling period on insulator using c...In this study, we investigate the fabrication of periodically poled lithium niobate(PPLN) microdisk cavities on a chip. These resonators are fabricated from a PPLN film with a 16 μm poling period on insulator using conventional microfabrication techniques.The quality factor of the PPLN microdisk resonators with a 40-μm radius and a 700-nm thickness is 6.7×10~5. Second harmonic generation(SHG) with an efficiency of 2.2×10^(-6) mW(-1) is demonstrated in the fabricated PPLN microdisks. The nonlinear conversion efficiency could be considerably enhanced by optimizing the period and pattern of the poled structure and by improving the cavity quality factors.展开更多
Conventionally, metallic nanostructures are used for surface-enhanced Raman spectroscopy(SERS), but recently there has been increasing interest in the enhancement of Raman scattering from dielectric substrates due to ...Conventionally, metallic nanostructures are used for surface-enhanced Raman spectroscopy(SERS), but recently there has been increasing interest in the enhancement of Raman scattering from dielectric substrates due to their improved stability and biocompatibility compared with metallic substrates. Here, we report the observation of enhanced Raman scattering from rhodamine 6 G molecules coated on silica microspheres. We excite the whispering gallery modes(WGMs) supported in the microspheres with a tapered fiber coupler for efficient WGM excitation, and the Raman enhancement can be attributed to the WGM mechanism. Strong resonance enhancement in pump laser intensity and modified Raman emission from the Purcell effect in the microsphere resonator are observed from the experiment and compared with theoretical results. A total Raman enhancement factor of 1.4 × 10~4 is observed, with contribution mostly from the enhancement in pump laser intensity. Our results show that, with an efficient pumping scheme, dielectric microspheres are a viable alternative to metallic SERS substrates.展开更多
Optical whispering gallery microcavities with high-quality factors have shown great potential toward achieveing ultrahigh-sensitivity sensing up to a single molecule or nanoparticle, which raises a huge demand on a de...Optical whispering gallery microcavities with high-quality factors have shown great potential toward achieveing ultrahigh-sensitivity sensing up to a single molecule or nanoparticle, which raises a huge demand on a deep theoretical insight into the crucial phenomena such as the mode shift, mode splitting, and mode broadening in sensing experiments. Here we propose an intuitive model to analyze these phenomena from the viewpoint of the nanoparticle-induced multiple scattering of the azimuthally propagating mode(APM). The model unveils explicit relations between these phenomena and the phase change and energy loss of the APM when scattered at the nanoparticle; the model also explains the observed polarization-dependent preservation of one resonance and the particle-dependent redshift or blueshift. The model indicates that the particle-induced coupling between the pair of unperturbed degenerate whispering gallery modes(WGMs) and the coupling between the WGMs and the free-space radiation modes, which are widely adopted in current theoretical formalisms, are realized via the reflection and scattering-induced free-space radiation of the APM, respectively, and additionally exhibits the contribution of cross coupling between the unperturbed WGMs and other different WGMs to forming the splittingresonant modes, especially for large particles.展开更多
We report the fabrication and optical characterization of spherical whispering gallery mode(WGM) resonators made from ultraviolet(UV)-curable adhesive. The fabricated microspheres have good sphericity and surface smoo...We report the fabrication and optical characterization of spherical whispering gallery mode(WGM) resonators made from ultraviolet(UV)-curable adhesive. The fabricated microspheres have good sphericity and surface smoothness, and can directly adhere to the tip of half-tapered fibers for easy manipulation. WGMs are e?ciently excited in the microsphere using an evanescent field of the tapered silica optical fibers. Resonances with quality factors of 1.3×10 5 are observed. The dependence of wavelength shifts of WGM resonances on the input light powers shows that the resonant wavelength of the proposed microsphere resonators can be tuned thermo-optically.展开更多
A whispering gallery mode resonator(WGMR)filter can narrow laser linewidth while significantly changing the output power characteristics of fiber laser system.It is found that traditional laser output power model is i...A whispering gallery mode resonator(WGMR)filter can narrow laser linewidth while significantly changing the output power characteristics of fiber laser system.It is found that traditional laser output power model is invalid.We report a correction model of a narrow linewidth fiber laser filtered with a WGMR to analyze its power.We believe that the loss of the laser system and the threshold gain increase caused by the WGMR filter lead to the predominate amplified spontaneous emission during the original laser period.According to that,we assume the correction coefficient is an exponential decay related to the Er-doped fiber length in the large loss situation,and we verify it experimentally.As a result,the correction model is valid for WGMR-filtered fiber laser.展开更多
With the support by the National Natural Science Foundation of China,Chinese Academy of Sciences,and Ministry of Science and Technology of China,the research group led by Dr.Dong Chunhua(董春华)at the CAS Key Lab of Q...With the support by the National Natural Science Foundation of China,Chinese Academy of Sciences,and Ministry of Science and Technology of China,the research group led by Dr.Dong Chunhua(董春华)at the CAS Key Lab of Quantum Information,University of Science and Technology of China。展开更多
In this paper,we experimentally investigate the tuning characteristics of laser modes for an ultrahigh-Q Er^(3+)-doped microbottle resonator(MBR)based on the whispering gallery mode(WGM).Thanks to the optimized Er^(3+...In this paper,we experimentally investigate the tuning characteristics of laser modes for an ultrahigh-Q Er^(3+)-doped microbottle resonator(MBR)based on the whispering gallery mode(WGM).Thanks to the optimized Er^(3+)doping technique,the laser threshold could be as low as 70μW.Benefiting from the abundant axial modes and radial modes of the MBR,our experiments demonstrate that the number of laser modes can be flexibly controlled by varying the pump power,adjusting the coupling positions along the axis of the MBR,as well as modifying the coupling diameter of the tapered fiber.The laser mode switching is performed from single-mode to multimodes.Furthermore,different from the traditional external tuning method,we propose a simple and stable approach for continuous wavelength tuning of the laser mode based on the thermal effect associated with the high Q MBR.By precisely adjusting the pump laser wavelength,the emitted laser wavelength can be tuned over a range of 0.102 nm with a high linearity of 99.96%.The engineering of laser mode switching and precise wavelength tuning of the Er^(3+)-doped MBR is expected to have promising applications in miniature tunable single-mode lasers,laser precision measurement,and so on.展开更多
Based on optofluidics and whispering gallery mode(WGM)theory,here an optofluidic refractive index sensor with microtube-coupled suspended core fiber(SCF)is proposed.It solves the issues of general sensors with microca...Based on optofluidics and whispering gallery mode(WGM)theory,here an optofluidic refractive index sensor with microtube-coupled suspended core fiber(SCF)is proposed.It solves the issues of general sensors with microcavity-coupled fiber taper such as too fragile,unstable performance due to open coupling,poor portability and repeatability,while overcoming the poor performance of low refractive index sensing in general full-package fiber sensors.The sensor only needs a very small amount of liquid sample(about 1.8 nL).The proposed sensor combines the excellent performance of full package,optofluidics and WGM resonator.The resonant characteristics and sensing performance of the sensor are analyzed and discussed by the theoretical simulation.The simulation results indicate that the sensor has a wide refractive index sensing range(1.330-1.700)and good performance.The resonance wavelength shift has a good linear relationship with the liquid refractive index variation.In the low refractive index region,the sensitivity is 222.5-247.5 nm/RIU,Q-factor is 1.03×10^(3) and the detection limit is 3.64×10^(-4) RIU.In the medium and high refractive index regions,the sensitivity is 564.4-846.2 nm/RIU,Q-factor is up to 8.62×10^(4),and the detection limit can be as low as 1.29×10^(-6) RIU.The sensor exhibits a high sensitivity,a high Q-factor and a very low detection limit.展开更多
Microsphere and microcylinder-assisted microscopy(MAM)has grown steadily over the last decade and is still an intensively studied optical far-field imaging technique that promises to overcome the fundamental lateral r...Microsphere and microcylinder-assisted microscopy(MAM)has grown steadily over the last decade and is still an intensively studied optical far-field imaging technique that promises to overcome the fundamental lateral resolution limit of microscopy.However,the physical effects leading to resolution enhancement are still frequently debated.In addition,various configurations of MAM operating in transmission mode as well as reflection mode are examined,and the results are sometimes generalized.We present a rigorous simulation model of MAM and introduce a way to quantify the resolution enhancement.The lateral resolution is compared for microscope arrangements in reflection and transmission modes.Furthermore,we discuss different physical effects with respect to their contribution to resolution enhancement.The results indicate that the effects impacting the resolution in MAM strongly depend on the arrangement of the microscope and the measurement object.As a highlight,we outline that evanescent waves in combination with whispering gallery modes also improve the imaging capabilities,enabling super-resolution under certain circumstances.This result is contrary to the conclusions drawn from previous studies,where phase objects have been analyzed,and thus further emphasizes the complexity of the physical mechanisms underlying MAM.展开更多
基金This work was also supported by the Ministry of Science and Higher Education of the Russian Federation(project no.14.W03.31.0008)in part by the Russian Science Foundation(project no.20-12-00389)+1 种基金in part by the Russian Foundation for Basic Research(projects no.20-02-00715,no.21-58-10005,no.21-57-10001).Z.B.Wang acknowledges European ERDF grants(CPE 81400 and SPARCII c81133)through WEFO,and Royal society grants(IEC\NSFC\181378 and IEC\R2\202178).
文摘We show that electric field on the plane surface of truncated sphere or cylinders(so called Janus particles)have sharp resonances versus the depth of removed segment of a sphere or cylinder.These resonances are related to the excited whispering gallery waves caused by truncation.It is a new mechanism of the field localization.Optimization of this effect for cylinders permits to reach a super resolution in the line thickness,which can be used for contact optical lithography.
文摘During the last decades the whispering gallery mode based sensors have become a prominent solution for label-free sensing of various physical and chemical parameters.At the same time,the widespread utilization of the approach is hindered by the restricted applicability of the known configurations for ambient variations quantification outside the laboratory conditions and their low affordability,where necessity on the spectrally-resolved data collection is among the main limiting factors.In this paper we demonstrate the first realization of an affordable whispering gallery mode sensor powered by deep learning and multi-resonator imaging at a fixed frequency.It has been shown that the approach enables refractive index unit(RIU)prediction with an absolute error at 3×10^(-6) level for dynamic range of the RIU variations from 0 to 2×10^(-3) with temporal resolution of several milliseconds and instrument-driven detection limit of 3×10−5.High sensing accuracy together with instrumental affordability and production simplicity places the reported detector among the most cost-effective realizations of the whispering gallery mode approach.The proposed solution is expected to have a great impact on the shift of the whole sensing paradigm away from the model-based and to the flexible self-learning solutions.
基金＊Supported by National Natural Science Foundation of China under Grant Nos. 10874134, 11004001, and 10947115 and Anhui Province for Young Teachers Foundation under Crant No. 2010SQRL037ZD
文摘We investigate theoretically the single-photon scattering by a A-type three-level system interacting with a whispering-gallery-type resonator which is coupled to a one-dimensional waveguide by full quantum-mechanical approach. The single-photon transmission amplitude and reflection amplitude are obtained exactly via real-space approach. The single-photon transport properties controlling by classic optical field are discussed. The critical coupling condition in the coupled waveguide-whispering-gallery resonator-atom with three-level system is also analyzed.
基金supported financially by the State Key Program of National Natural Science Foundation of China(No.61734008)the National Natural Science Foundation of China(Nos.61574097,61604170 and 61604169)+1 种基金the National Key Research and Development Program of China(Nos.2016YFA0201101 and 2017YFB0404100)the National Key Scientific Instrument and Equipment Development Project(No.11327804)。
文摘The III-nitride semiconductor microdisk laser exhibits high quality factor and low excitation threshold with broad development potential in the field of nanophotonics such as nanoscale light-emitting devices and on-chip optical integration.So far,many works have been focused on process synthesis and nanostructural design of microdisk lasers.Nevertheless,there are still some limitations in the existing optical resonance mode which is an important internal influence factor for lasing characteristics.In this work,a new double-triangular whispering-gallery mode(D3-WGM)lasing from a hexagonal GaN microdisk with a high quality(Q)factor of 3049 and an excitation threshold of around 11.5μW has been experimentally demonstrated.In addition,the optical properties of hexagonal-WGM(6-WGM),triangular-WGM(3-WGM)and D3-WGM lasing from microdisk are explored by numerical calculation and Comsol simulation.These results confirm that the D3-WGM lasing has its own significant performance advantages,namely high Q factor and easy light emission.Based on this novel laser mode characteristic,microcavity lasers are expected to be further developed and applied in the field of nanophotonics.
基金Supported by the National Basic Research Program of China （ ＂973＂ Program） （ 2011 CB013000 ） the National Natural Sci- ence Foundation of China （NSFC） （ 90923039 51105038）
文摘A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode （WGM） resonance in bent optical fibers,is proposed. The sensor is composed of a single loop formed by loosely tying a knot using single mode fiber. To measure the transmission spectra, a tunable laser and an optic power meter are connected to the two ends of fi- ber loop, respectively. Significant WGM resonances occur over the investigated wavelength range for all the sensors with different bend radius. The angular-displacement sensitivity is studied in the range from -0. 1°to 0. 1°. The detection limit of 1.49 × 10 ^-7 rad can be achieved for the detecting system with the resolution of lpm. The simple loop-structure fiber sensor has potential application prospect in the field of architecture or bridge building with low detection limit and low cost.
基金supported by the National Natural Science Foundation of China(Nos.U1304608 and 61774053)the Project of Henan Provincial Department of Science and Technology(No.182102410047)the Program of Henan Polytechnic University(No.B2014-020)。
文摘In this letter,a humidity sensor is demonstrated by applying a whispering gallery mode(WGM)from a microsphere resonator onto the ZnO nanorods coated glass surface.The diameter of the microsphere was 234μm and the glass surface was coated with ZnO nanorods using the hydrothermal method at growth duration of 12 h.A significant response to humidity level ranging from 35%RH to 85%RH has been observed with the sensitivity of 0.0142 nm/%RH.The proposed humidity sensor has successfully employed to enhance interaction between the whispering gallery mode evanescent and surrounds analyte with the assistance of ZnO nanorods coated glass.
基金Royal Society of New Zealand Marsden Council fund(20UOO-080)。
文摘Lithium tetraborate(LB4)is a lithium borate compound known for its exceptional linear and nonlinear optical properties,including a wide transparency range(0.16–3.5μm)and high Raman gain.Here,a millimeter-sized LB4 whispering gallery mode(WGM)resonator with a record quality factor of 2.0×10^(9) at 517 nm was fabricated using single-point diamond cutting.Pumped with about 10 m W at 517 nm,it demonstrated four cascaded stimulated Raman scattering(SRS)peaks(537–608 nm),with the first-order SRS achieving a threshold of 0.71 m W and 7.2% slope efficiency.To our knowledge,this marks the first LB4 WGM resonator Raman laser.
基金National Natural Science Foundation of China(62122027,62075063,62205109,62405092,52202004)Postdoctoral Fellowship Program of CPSF(GZC20230852)+1 种基金State Key Laboratory of Luminescent Materials and Devices(Skllmd-2024-12)China Scholarship Council Grant(202406150002)。
文摘Upconversion nanoparticles(UCNPs)have attracted considerable interest due to their large anti-Stokes shift,offering promising applications in lasing.Here,multi-wavelength upconversion whispering gallery mode(WGM)lasing is demonstrated in silica microspheres coated with NaYF_(4)@NaYbF_(4):1%Tm^(3+)@NaYF_(4)nanoparticles and coupled with tapered fibers.Under continuous-wave 980 nm pumping,low-threshold lasing is achieved across Tm3+transitions from near-infrared to visible,with an ultra-low threshold of 0.61μWfor the 3H_(4)→3H_(6)transition.Additionally,upconversion laser output can also be achieved in Er^(3+)-and Ho^(3+)-activated microspheres.These results establish tapered fiber coupling as a versatile approach for enhancing upconversion microlasers.
文摘This paper investigates the use of artificial neural networks(ANNs)as a viable digital twin or alternative to the typical whispering gallery mode(WGM)optical sensors in engineering systems,especially in dynamic environments like robotics.Because of its fragility and limited endurance,the WGM sensor which is based on micro-optical resonators is inappropriate in these kinds of situations.In order to address these issues,the paper suggests an ANN that is specifically designed for the system and makes use of the WGM sensor’s high-quality factor(Q-factor).By extending the applicability and endurance to dynamic contexts and reducing fragility problems,the ANN seeks to give high-resolution measurement.In order to minimize post-processing requirements and maintain system robustness,the study goal is for the ANN to function as a representative predictor of the WGM sensor output.The GUCnoid 1.0 humanoid robot is used in the paper as an example to show how the WGM optical sensors may improve humanoid robot performance for a variety of applications.The results of the experiments demonstrate that the sensitivity,precision,and resolution of ANN outputs and actual WGM shifts are equivalent.As a consequence,current obstacles to the widespread use of high-precision sensing in the robotics industry are removed,and the potential of ANNs as virtual substitutes or the digital twin for genuine WGM sensors in robotics systems is validated.So,this paper can be very beneficial not only to the sensing technologies that are used in robotics,which are subjected to the dynamic environments,but also to the industrial automation and human-machine interface.
基金supported by the National Natural Science Foundation of China(Nos.52075131 and 62305006)the Jiangsu Natural Science Foundation(Basic Research Program of Jiangsu Province)(No.BK20230286)。
文摘Whispering gallery mode resonators(WGMRs)are used as excellent optical feedback components of narrow-linewidth fiber lasers,applied from distributed fiber sensing to optical fiber communication.However,WGMRs lead to output of a few microwatts and serious multi-modes in lasers.In this Letter,we fabricated the specially designed WGMR with an overcoupling structure,and its quality(Q)factor was over 10^(9).It improved laser output power significantly.Based on that,dynamic population gratings were applied successfully in the laser.Finally,a single-frequency WGMR fiber laser was realized.Its linewidth was less than 1.07 kHz,its output power was over 0.107 mW,and its spectral signal-to-noise ratio(SNR)was nearly 50 dB.Our research offers a new scheme of a single-frequency narrow-linewidth WGMR fiber laser.
基金supported by the Shenzhen Fundamental Research Projects(Grant No.JCYJ20160427183259083)the National Natural Science Foundation of China(Grant No.91850204)the Shenzhen Engineering Laboratory on Organic-Inorganic Perovskite Devices
文摘Whispering gallery modes (WGMs) were first discovered for sound waves in the whispering gallery of St Paul’s Cathedral and explained by Rayleigh [1] in 1878. In 1961, Garrett et al.[2] applied the concept of WGMs to optical systems and realized stimulated emissions in Sm2+-doped CaF2 spheres.Since then, WGMs have been widely and intensively studied in a range of micro-sized systems, including microdroplets,microspheres, microtoroids, microdisks, and microtubes.
基金supported by the National Natural Science Foundation of China(Grant Nos.11734009,11674181,11774182,and 11674184)the 111 Project(Grant No.B07013)+1 种基金PCSIRT(Grant No.IRT 13R29)CAS Interdisciplinary Innovation Team
文摘In this study, we investigate the fabrication of periodically poled lithium niobate(PPLN) microdisk cavities on a chip. These resonators are fabricated from a PPLN film with a 16 μm poling period on insulator using conventional microfabrication techniques.The quality factor of the PPLN microdisk resonators with a 40-μm radius and a 700-nm thickness is 6.7×10~5. Second harmonic generation(SHG) with an efficiency of 2.2×10^(-6) mW(-1) is demonstrated in the fabricated PPLN microdisks. The nonlinear conversion efficiency could be considerably enhanced by optimizing the period and pattern of the poled structure and by improving the cavity quality factors.
基金National Science Foundation(NSF)(CBET1264750,CBET 1264997)Army Research Office(ARO)(W911NF-16-1-0339)
文摘Conventionally, metallic nanostructures are used for surface-enhanced Raman spectroscopy(SERS), but recently there has been increasing interest in the enhancement of Raman scattering from dielectric substrates due to their improved stability and biocompatibility compared with metallic substrates. Here, we report the observation of enhanced Raman scattering from rhodamine 6 G molecules coated on silica microspheres. We excite the whispering gallery modes(WGMs) supported in the microspheres with a tapered fiber coupler for efficient WGM excitation, and the Raman enhancement can be attributed to the WGM mechanism. Strong resonance enhancement in pump laser intensity and modified Raman emission from the Purcell effect in the microsphere resonator are observed from the experiment and compared with theoretical results. A total Raman enhancement factor of 1.4 × 10~4 is observed, with contribution mostly from the enhancement in pump laser intensity. Our results show that, with an efficient pumping scheme, dielectric microspheres are a viable alternative to metallic SERS substrates.
基金National Key Basic Research Program of China(2013CB328701)National Natural Science Foundation of China(NSFC)(61322508,11504270)
文摘Optical whispering gallery microcavities with high-quality factors have shown great potential toward achieveing ultrahigh-sensitivity sensing up to a single molecule or nanoparticle, which raises a huge demand on a deep theoretical insight into the crucial phenomena such as the mode shift, mode splitting, and mode broadening in sensing experiments. Here we propose an intuitive model to analyze these phenomena from the viewpoint of the nanoparticle-induced multiple scattering of the azimuthally propagating mode(APM). The model unveils explicit relations between these phenomena and the phase change and energy loss of the APM when scattered at the nanoparticle; the model also explains the observed polarization-dependent preservation of one resonance and the particle-dependent redshift or blueshift. The model indicates that the particle-induced coupling between the pair of unperturbed degenerate whispering gallery modes(WGMs) and the coupling between the WGMs and the free-space radiation modes, which are widely adopted in current theoretical formalisms, are realized via the reflection and scattering-induced free-space radiation of the APM, respectively, and additionally exhibits the contribution of cross coupling between the unperturbed WGMs and other different WGMs to forming the splittingresonant modes, especially for large particles.
基金supported by the National Natural Science Foundation of China(No.61275050)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120121110034)the Fundamental Research Funds for the Central Universities of Xiamen University(Nos.2010121059 and 2011121048)
文摘We report the fabrication and optical characterization of spherical whispering gallery mode(WGM) resonators made from ultraviolet(UV)-curable adhesive. The fabricated microspheres have good sphericity and surface smoothness, and can directly adhere to the tip of half-tapered fibers for easy manipulation. WGMs are e?ciently excited in the microsphere using an evanescent field of the tapered silica optical fibers. Resonances with quality factors of 1.3×10 5 are observed. The dependence of wavelength shifts of WGM resonances on the input light powers shows that the resonant wavelength of the proposed microsphere resonators can be tuned thermo-optically.
基金supported by the National Natural Science Foundation of China(NSFC)(No.52075131)。
文摘A whispering gallery mode resonator(WGMR)filter can narrow laser linewidth while significantly changing the output power characteristics of fiber laser system.It is found that traditional laser output power model is invalid.We report a correction model of a narrow linewidth fiber laser filtered with a WGMR to analyze its power.We believe that the loss of the laser system and the threshold gain increase caused by the WGMR filter lead to the predominate amplified spontaneous emission during the original laser period.According to that,we assume the correction coefficient is an exponential decay related to the Er-doped fiber length in the large loss situation,and we verify it experimentally.As a result,the correction model is valid for WGMR-filtered fiber laser.
文摘With the support by the National Natural Science Foundation of China,Chinese Academy of Sciences,and Ministry of Science and Technology of China,the research group led by Dr.Dong Chunhua(董春华)at the CAS Key Lab of Quantum Information,University of Science and Technology of China。
基金supported by the National Natural Science Foundation of China(Nos.62205001 and 62275001)。
文摘In this paper,we experimentally investigate the tuning characteristics of laser modes for an ultrahigh-Q Er^(3+)-doped microbottle resonator(MBR)based on the whispering gallery mode(WGM).Thanks to the optimized Er^(3+)doping technique,the laser threshold could be as low as 70μW.Benefiting from the abundant axial modes and radial modes of the MBR,our experiments demonstrate that the number of laser modes can be flexibly controlled by varying the pump power,adjusting the coupling positions along the axis of the MBR,as well as modifying the coupling diameter of the tapered fiber.The laser mode switching is performed from single-mode to multimodes.Furthermore,different from the traditional external tuning method,we propose a simple and stable approach for continuous wavelength tuning of the laser mode based on the thermal effect associated with the high Q MBR.By precisely adjusting the pump laser wavelength,the emitted laser wavelength can be tuned over a range of 0.102 nm with a high linearity of 99.96%.The engineering of laser mode switching and precise wavelength tuning of the Er^(3+)-doped MBR is expected to have promising applications in miniature tunable single-mode lasers,laser precision measurement,and so on.
基金supported by the National Natural Science Foundation of China(No.12174199)the Wanjing Horizontal Research and Development Fund for Nature(No.HJ1060319960015).
文摘Based on optofluidics and whispering gallery mode(WGM)theory,here an optofluidic refractive index sensor with microtube-coupled suspended core fiber(SCF)is proposed.It solves the issues of general sensors with microcavity-coupled fiber taper such as too fragile,unstable performance due to open coupling,poor portability and repeatability,while overcoming the poor performance of low refractive index sensing in general full-package fiber sensors.The sensor only needs a very small amount of liquid sample(about 1.8 nL).The proposed sensor combines the excellent performance of full package,optofluidics and WGM resonator.The resonant characteristics and sensing performance of the sensor are analyzed and discussed by the theoretical simulation.The simulation results indicate that the sensor has a wide refractive index sensing range(1.330-1.700)and good performance.The resonance wavelength shift has a good linear relationship with the liquid refractive index variation.In the low refractive index region,the sensitivity is 222.5-247.5 nm/RIU,Q-factor is 1.03×10^(3) and the detection limit is 3.64×10^(-4) RIU.In the medium and high refractive index regions,the sensitivity is 564.4-846.2 nm/RIU,Q-factor is up to 8.62×10^(4),and the detection limit can be as low as 1.29×10^(-6) RIU.The sensor exhibits a high sensitivity,a high Q-factor and a very low detection limit.
基金supported by the German Research Foundation(DFG)(Grant Nos.LE 992/14-3 and LE 992/15-3).
文摘Microsphere and microcylinder-assisted microscopy(MAM)has grown steadily over the last decade and is still an intensively studied optical far-field imaging technique that promises to overcome the fundamental lateral resolution limit of microscopy.However,the physical effects leading to resolution enhancement are still frequently debated.In addition,various configurations of MAM operating in transmission mode as well as reflection mode are examined,and the results are sometimes generalized.We present a rigorous simulation model of MAM and introduce a way to quantify the resolution enhancement.The lateral resolution is compared for microscope arrangements in reflection and transmission modes.Furthermore,we discuss different physical effects with respect to their contribution to resolution enhancement.The results indicate that the effects impacting the resolution in MAM strongly depend on the arrangement of the microscope and the measurement object.As a highlight,we outline that evanescent waves in combination with whispering gallery modes also improve the imaging capabilities,enabling super-resolution under certain circumstances.This result is contrary to the conclusions drawn from previous studies,where phase objects have been analyzed,and thus further emphasizes the complexity of the physical mechanisms underlying MAM.
