Herein,a method of true-temperature inversion for a multi-wavelength pyrometer based on fractional-order particle-swarm optimization is proposed for difficult inversion problems with unknown emissivity.Fractional-order...Herein,a method of true-temperature inversion for a multi-wavelength pyrometer based on fractional-order particle-swarm optimization is proposed for difficult inversion problems with unknown emissivity.Fractional-order calculus has the inherent advantage of easily jumping out of local extreme values;here,it is introduced into the particle-swarm algorithm to invert the true temperature.An improved adaptive-adjustment mechanism is applied to automatically adjust the current velocity order of the particles and update their velocity and position values,increasing the accuracy of the true temperature values.The results of simulations using the proposed algorithm were compared with three algorithms using typical emissivity models:the internal penalty function algorithm,the optimization function(fmincon)algorithm,and the conventional particle-swarm optimization algorithm.The results show that the proposed algorithm has good accuracy for true-temperature inversion.Actual experimental results from a rocket-motor plume were used to demonstrate that the true-temperature inversion results of this algorithm are in good agreement with the theoretical true-temperature values.展开更多
In general, the dependence of the logarithm of the emissivity upon wavelength is usually used in the treatment of data measured by multi-wavelength pyrometer. In this paper, the suitability of this expression for diff...In general, the dependence of the logarithm of the emissivity upon wavelength is usually used in the treatment of data measured by multi-wavelength pyrometer. In this paper, the suitability of this expression for different materials has been examined. Further more, an effective method for automatically searching the mathematical model between emissivity and wavelength has been procsed. The calculated results show that the accuracy is improved by using this data treatment method.展开更多
The surface temperature of casting slab is an important parameter in the metallurgy field. Because the surface emissivity is uncertain and also unknown, it is difficult to measure the slab surface temperature accurate...The surface temperature of casting slab is an important parameter in the metallurgy field. Because the surface emissivity is uncertain and also unknown, it is difficult to measure the slab surface temperature accurately. A method based on preceded reflector and multi-wavelength was put forward to deal with the difficulty in surface temperature measurement of casting slab. On the premise of preceded reflector and non-preceded reflector, the method establishes the radiation energy equations and works out the emissivity and temperature in the equations. Also, the multilayer modeling of casting slab surface and multiple reflection-absorption process modeling were built by Monte Carlo method. The temperature measuring method had been applied in the continuous casting field. In order to verify the measured result, the thermal imaging method was adopted when the slab surface emissivity was set by repeated tests. Finally, the measured and verified temperature curves keep a same tendency and the error of the values is lower than 5℃. The comparison result shows that the method can measure temperature accurately.展开更多
We report on a study of terahertz(THz) generation using implanted In Ga As photomixers and multi-wavelength quantum dot lasers. We carry out In Ga As materials growth, optical characterization, device design and fabri...We report on a study of terahertz(THz) generation using implanted In Ga As photomixers and multi-wavelength quantum dot lasers. We carry out In Ga As materials growth, optical characterization, device design and fabrication, and photomixing experiments. This approach is capable of generating a comb of electromagnetic radiation from microwave to terahertz. For shortening photomixer carrier lifetime, we employ proton implantation into an epitaxial layer of lattice matched In Ga As grown on InP. Under a 1.55 μm multimode In GaAs/In GaAsP quantum dot laser excitation, a frequency comb with a constant frequency spacing of 50 GHz generated on the photomixer is measured, which corresponds to the beats of the laser longitudinal modes. The measurement is performed with a Fourier transform infrared spectrometer. This approach affords a convenient method to achieve a broadband multi-peak coherent THz source.展开更多
Multi-wavelength continuous-wave self-Raman laser with an a-cut composite YVO4/Nd:YVO4/YVO4 crystal pumped by an 879-nm wavelength-locked laser diode is demonstrated for the first time.Multi-wavelength Raman lasers at...Multi-wavelength continuous-wave self-Raman laser with an a-cut composite YVO4/Nd:YVO4/YVO4 crystal pumped by an 879-nm wavelength-locked laser diode is demonstrated for the first time.Multi-wavelength Raman lasers at 1168.4,1176,1178.7,and 1201.6 nm are achieved by the first Stokes shift of the multi-wavelength fundamental lasers at 1064,1066.7,1073.6,1084,and 1085.6 nm with two Raman shifts of 890 and 816 cm^-1.A maximum Raman output power of 2.56 W is achieved through the use of a 20-mm-long composite crystal,with a corresponding optical conversion efficiency of 9.8%.The polarization directions of different fundamental and Raman lasers are investigated and found to be orthogonalπandσpolarizations.These orthogonally polarized multi-wavelength lasers with small wavelength separation pave the way to the development of a potential laser source for application in spectral analysis,laser radar and THz generation.展开更多
A method for measurement of ultra-low flying height in head-disk spacing is described. Three different wavelengths are selected out from white light by filters to measure the spacing simultaneously. Besides solving th...A method for measurement of ultra-low flying height in head-disk spacing is described. Three different wavelengths are selected out from white light by filters to measure the spacing simultaneously. Besides solving the ambiguity problem, a more reliable result is achieved by using weighted average of measurement results from three different wavelengths, where the weight is dependent upon spacing. Fringe-bunching correction algorithm （FBC） and spot-tilling technique are adopted to suppress calibration and random errors. Moreover, incident bandwidth correction （IBC） method is introduced to compensate the error caused by low monochromaticity of incident light. Based on dynamic flying height tester （DFHT Ⅱ）, with the redesigned of photo-electric conversion and signal acquirement module, an instrument has been developed. And comparing the experimental data from the instrument with those from a KLA-FHT D6, the discrepancy is less than 5%. It indicates that the instrument is suitable to perform ultra-low flying height measurement and satisfies the reauirement of magnetic heads manufacturing.展开更多
A seed laser oscillating at different frequencies is proved to have the potential to mitigate the stimulated Brillouin scattering（SBS） effect in a fiber amplifier,which may increase the emission power of a coherent ...A seed laser oscillating at different frequencies is proved to have the potential to mitigate the stimulated Brillouin scattering（SBS） effect in a fiber amplifier,which may increase the emission power of a coherent beam combination（CBC） system greatly.In this study,a basic mathematical model describing the multi-wavelength CBC is proposed on the fundamentals of CBC.A useful method for estimating the combination effect and analysing the feasibility and the validity of the multi-wavelength coherent combination is provided.In the numerical analysis,accordant results with four-wavelength four-channel CBC experiments are obtained.Through calculations of some examples with certain spectra,the unanticipated excellent combination effect with a few frequencies involved is explained,and the dependence of the combination effect on the variance of the amplifier chain length and the channel number is clarified.展开更多
This investigation developed a new method for determining metal complex's property containing the stepwise real absorptivity(epsilon) and stability constant (K-m). The correction equation of the multi-wavelength s...This investigation developed a new method for determining metal complex's property containing the stepwise real absorptivity(epsilon) and stability constant (K-m). The correction equation of the multi-wavelength spectral absorption was established for the simultaneous determination of various complexes to give high accuracy for trace analysis. This method was more acceptable in theory and simpler in operation than the classical methods.展开更多
Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was prepared.In order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state dens...Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was prepared.In order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state density of the sample.At the same time,Nd^(3+)was introduced to transfer the energy to Ho^(3+)pumped with a 793 nm laser(Nd^(3+):4 F5/2,4 F3/2→Ho^(3+):5 I6).The effect of different halogen ion on the luminescent properties of the fluoride halide glass was compared.The results show that the luminescent intensity of infrared increases with the introduction of different halogen ions.By comparison,it is found that the sample with I-has the strongest luminescence of 1064 nm,2.0μm and 2.9μm.This is consistent with the calculated J-O intensity parameters.In addition,the 2.0 and 2.9μm emission of Ho^(3+)pumped with a 450 nm laser will not disappear.A mid-infrared sample with multi-wavelength excitation and multi-wavelength emission can be obtained.Nd^(3+)/Ho^(3+)co-doped fluoride halide glasses with 1064 nm,2.0μm and 2.9μm luminescence were prepared by melt quenching method.The luminescent mechanism and the energy transfer process between the two ions of Nd^(3+)/Ho^(3+)co-doped fluoride halide glass were studied.The J-O parameters,luminescence lifetime and absorption emission cross-sectional area of Ho^(3+)and Nd^(3+)were calculated,respectively.It is found that the value ofΩ2 in the glass matrix increases with the introduction of different halogen ions,whileΩ4 andΩ6 do not change obviously in different glass compositions.This is because the environment of the crystal field around the rare earth ions changes.The crystal phase and phonon energy of the sample were analyzed by X-ray diffraction pattern and a Fourier transform infrared spectrometer,respectively.Based on the above spectra and data(phonon energy is 634.71 cm-1),it can be predicted that Nd^(3+)/Ho^(3+)co-doped fluoride halide glass is a potential mid-infrared luminescent material.展开更多
A method of measuring turbidity based on a multi-wavelength spectral sensor is proposed by using SFH4737 broad-band infrared LED,a multi-wavelength spectral sensor and independently developed data processing software....A method of measuring turbidity based on a multi-wavelength spectral sensor is proposed by using SFH4737 broad-band infrared LED,a multi-wavelength spectral sensor and independently developed data processing software.Combining multiple wavelength data from the sensor,the unitary and multivariate fitting models were constructed to investigate the relationship among light intensity information,absorbance and turbidity,respectively.The turbidity of the actual water bodies was measured separately by using proposed method and a commercially visible spectrophotometer.The independent-samples T test(p>0.05)showed that there was no significant difference between the method in this paper and the standard assay method.The method is simple and inexpensive,and can be applied to the rapid detection of water turbidity,providing a new way of industrial online measurement.展开更多
A tunable self-seeded multi-wavelength Brillouin-erbium fiber laser(BEFL) is proposed and demonstrated based on a few-mode fiber filter(FMFF) with varying temperature. The FMFF configuration is a section of uncoated f...A tunable self-seeded multi-wavelength Brillouin-erbium fiber laser(BEFL) is proposed and demonstrated based on a few-mode fiber filter(FMFF) with varying temperature. The FMFF configuration is a section of uncoated few-mode fiber(FMF) sandwiched between two up-tapers. As the temperature varies from 25 °C to 125 °C, the transmission spectrum of FMFF moves towards the longer wavelength. The self-excited Brillouin pump is internally achieved by cascaded stimulated Brillouin scattering(SBS) in the single mode fiber(SMF). Then employing the FMFF temperature variation characteristics in the ring cavity fiber laser, the multi-wavelength of the output laser can be tuned, and the tunable range is about 8.0 nm. The generation of up to 15 Brillouin Stokes wavelengths with 16 d B optical signal-to-noise ratio(OSNR) is realized.展开更多
In this Letter,we propose and experimentally demonstrate,to the best of our knowledge,a novel compact power-equalized multi-wavelength laser(MWL)source for optical I/O technology.This multi-wavelength distributed feed...In this Letter,we propose and experimentally demonstrate,to the best of our knowledge,a novel compact power-equalized multi-wavelength laser(MWL)source for optical I/O technology.This multi-wavelength distributed feedback(DFB)laser array is used to achieve simultaneous emission of multiple wavelengths with balanced output power and stable single-mode operation.The reconstruction equivalent chirp technique is used to design and fabricate theπ-phase shifted DFB laser array to achieve precise wavelength spacing.The power equalizers(PEs)are monolithically integrated in front of the laser unit to equalize the output power.The experimental results show that the wavelength spacing of the proposed eight-channel MWL is 100 G±4.38 G,and the maximum deviation of the intensity(MDOI)is 1.00 dB under a 25℃working environment.Compared with the traditional MWL structure,the wavelength spacing error is reduced from 0.32 to 0.035 nm,and the MODI is reduced from 3.8 to 1.0 dB.The output power exceeds 25 mW when the current injected into the semiconductor optical amplifier(SOA)is 150 mA.Besides,the relative intensity noise(RIN)of all wavelengths is below-138 dB/Hz,and clear 25 Gb/s non-return-to-zero(NRZ)eye diagrams are obtained for the eight wavelengths with the external lithium-niobate Mach-Zehnder modulator.The superior performance of the proposed MWL makes it a promising method for low-bit-error optical I/O links and high-density chip interconnection systems.展开更多
Conventional microscopes designed for submicron resolution in biological research are hindered by a limited field of view,typically around 1 mm.This restriction poses a challenge when attempting to simultaneously anal...Conventional microscopes designed for submicron resolution in biological research are hindered by a limited field of view,typically around 1 mm.This restriction poses a challenge when attempting to simultaneously analyze various parts of a sample,such as different brain areas.In addition,conventional objective lenses struggle to perform consistently across the required range of wavelengths for brain imaging in vivo.Here we present a novel mesoscopic objective lens with an impressive field of view of 8 mm,a numerical aperture of 0.5,and a working wavelength range from 400 to 1000 nm.We achieved a resolution of 0.74μm in fluorescent beads imaging.The versatility of this lens was further demonstrated through high-quality images of mouse brain and kidney sections in a wide-field imaging system,a confocal laser scanning system,and a two-photon imaging system.This mesoscopic objective lens holds immense promise for advancing multi-wavelength imaging of large fields of view at high resolution.展开更多
Because of the complexity and difficulty of realizing a multi-wavelength soliton state,reports on its internal dynamic characteristics are scarce.In this study,the switching and periodic soliton explosion processes of...Because of the complexity and difficulty of realizing a multi-wavelength soliton state,reports on its internal dynamic characteristics are scarce.In this study,the switching and periodic soliton explosion processes of the multi-wavelength soliton state in a negative dispersion passively mode-locked fiber laser are realized.The generation of the multi-wavelength soliton state undergoes the process of noise,oscillation,and stable mode-locking,and the splitting and annihilation of solitons with different group velocities directly impact the generation and disappearance of three wavelengths.Positive and negative dispersion lead to different group velocities of solitons.The presence and displacement of solitons with different group velocities cause soliton collisions,which lead to soliton explosions.A soliton experiences relative phase oscillation,chaos,and oscillation,as well as convergence and separation before and after an explosion.With an increase in parameters related to pump power,single-soliton oscillation,multi-wavelength solitons,and chaos are found in experiments and simulations,proving the relevance and reliability between simulation and experimental results.This work promotes the dynamical study of multi-soliton collisions in nonlinear science and the development of chaos theory in multi-comb lasers.展开更多
This study demonstrates a kilowatt-level, spectrum-programmable, multi-wavelength fiber laser(MWFL) with wavelength, interval and intensity tunability. The central wavelength tuning range is 1060–1095 nm and the tuna...This study demonstrates a kilowatt-level, spectrum-programmable, multi-wavelength fiber laser(MWFL) with wavelength, interval and intensity tunability. The central wavelength tuning range is 1060–1095 nm and the tunable number is controllable from 1 to 5. The wavelength interval can be tuned from 6 to 32 nm and the intensity of each channel can be adjusted independently. Maximum output power up to approximately 1100 W has been achieved by master oscillator power amplifier structures. We also investigate the wavelength evolution experimentally considering the difference of gain competition, which may give a primary reference for kW-level high-power MWFL spectral manipulation. To the best of our knowledge, this is the highest output power ever reported for a programmable MWFL. Benefiting from its high power and flexible spectral manipulability, the proposed MWFL has great potential in versatile applications such as nonlinear frequency conversion and spectroscopy.展开更多
We propose and demonstrate the cascaded multi-wavelength mode-locked erbium-doped fiber laser(EDFL) based on ultralong-period gratings(ULPGs) for the first time, to the best of our knowledge.Study found that the ULPG ...We propose and demonstrate the cascaded multi-wavelength mode-locked erbium-doped fiber laser(EDFL) based on ultralong-period gratings(ULPGs) for the first time, to the best of our knowledge.Study found that the ULPG can be used as both a mode-locker for pulse shaping and a comb filter for multi-wavelength generation simultaneously.Using the dual-function of ULPG, three-, four-, five-, six-, and seven-wavelength mode-locked pulses are obtained in EDFL, seven of which are the largest number of wavelengths up to now.For the four-wavelength soliton pulses, their pulse width is about 7.8 ps.The maximum average output power and slope efficiency of these pulses are 8.4 m W and 2.03%, respectively.Besides the conventional pulses, hybrid soliton pulses composed of a four-wavelength pulse and single soliton are also observed.Finally, the effect of cavity dispersion on the multi-wavelength mode-locked pulses is also discussed.Our findings indicate that apart from common sensing and filtering, the ULPG may also possess attractive nonlinear pulse-shaping property for ultrafast photonics application.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.62205280)the Graduate Innovation Foundation of Yantai University(Grant No.GGIFYTU2348).
文摘Herein,a method of true-temperature inversion for a multi-wavelength pyrometer based on fractional-order particle-swarm optimization is proposed for difficult inversion problems with unknown emissivity.Fractional-order calculus has the inherent advantage of easily jumping out of local extreme values;here,it is introduced into the particle-swarm algorithm to invert the true temperature.An improved adaptive-adjustment mechanism is applied to automatically adjust the current velocity order of the particles and update their velocity and position values,increasing the accuracy of the true temperature values.The results of simulations using the proposed algorithm were compared with three algorithms using typical emissivity models:the internal penalty function algorithm,the optimization function(fmincon)algorithm,and the conventional particle-swarm optimization algorithm.The results show that the proposed algorithm has good accuracy for true-temperature inversion.Actual experimental results from a rocket-motor plume were used to demonstrate that the true-temperature inversion results of this algorithm are in good agreement with the theoretical true-temperature values.
文摘In general, the dependence of the logarithm of the emissivity upon wavelength is usually used in the treatment of data measured by multi-wavelength pyrometer. In this paper, the suitability of this expression for different materials has been examined. Further more, an effective method for automatically searching the mathematical model between emissivity and wavelength has been procsed. The calculated results show that the accuracy is improved by using this data treatment method.
基金Item Sponsored by National Natural Science Foundation of China(61004135)
文摘The surface temperature of casting slab is an important parameter in the metallurgy field. Because the surface emissivity is uncertain and also unknown, it is difficult to measure the slab surface temperature accurately. A method based on preceded reflector and multi-wavelength was put forward to deal with the difficulty in surface temperature measurement of casting slab. On the premise of preceded reflector and non-preceded reflector, the method establishes the radiation energy equations and works out the emissivity and temperature in the equations. Also, the multilayer modeling of casting slab surface and multiple reflection-absorption process modeling were built by Monte Carlo method. The temperature measuring method had been applied in the continuous casting field. In order to verify the measured result, the thermal imaging method was adopted when the slab surface emissivity was set by repeated tests. Finally, the measured and verified temperature curves keep a same tendency and the error of the values is lower than 5℃. The comparison result shows that the method can measure temperature accurately.
基金supported in part by NSERC. HCL thanks the support by the National Ma jor Basic Research Pro jects (2011CB925603)Shanghai Municipal Ma jor Basic Research Pro ject (09DJ1400102)
文摘We report on a study of terahertz(THz) generation using implanted In Ga As photomixers and multi-wavelength quantum dot lasers. We carry out In Ga As materials growth, optical characterization, device design and fabrication, and photomixing experiments. This approach is capable of generating a comb of electromagnetic radiation from microwave to terahertz. For shortening photomixer carrier lifetime, we employ proton implantation into an epitaxial layer of lattice matched In Ga As grown on InP. Under a 1.55 μm multimode In GaAs/In GaAsP quantum dot laser excitation, a frequency comb with a constant frequency spacing of 50 GHz generated on the photomixer is measured, which corresponds to the beats of the laser longitudinal modes. The measurement is performed with a Fourier transform infrared spectrometer. This approach affords a convenient method to achieve a broadband multi-peak coherent THz source.
基金Project supported by the National Natural Science Foundation of China(Grant No.11774301)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.11804292)
文摘Multi-wavelength continuous-wave self-Raman laser with an a-cut composite YVO4/Nd:YVO4/YVO4 crystal pumped by an 879-nm wavelength-locked laser diode is demonstrated for the first time.Multi-wavelength Raman lasers at 1168.4,1176,1178.7,and 1201.6 nm are achieved by the first Stokes shift of the multi-wavelength fundamental lasers at 1064,1066.7,1073.6,1084,and 1085.6 nm with two Raman shifts of 890 and 816 cm^-1.A maximum Raman output power of 2.56 W is achieved through the use of a 20-mm-long composite crystal,with a corresponding optical conversion efficiency of 9.8%.The polarization directions of different fundamental and Raman lasers are investigated and found to be orthogonalπandσpolarizations.These orthogonally polarized multi-wavelength lasers with small wavelength separation pave the way to the development of a potential laser source for application in spectral analysis,laser radar and THz generation.
基金National Basic Research Program of China(973 Program,No. 2003CB716207)National Natural Science Foundation of China(No.50775091)
文摘A method for measurement of ultra-low flying height in head-disk spacing is described. Three different wavelengths are selected out from white light by filters to measure the spacing simultaneously. Besides solving the ambiguity problem, a more reliable result is achieved by using weighted average of measurement results from three different wavelengths, where the weight is dependent upon spacing. Fringe-bunching correction algorithm （FBC） and spot-tilling technique are adopted to suppress calibration and random errors. Moreover, incident bandwidth correction （IBC） method is introduced to compensate the error caused by low monochromaticity of incident light. Based on dynamic flying height tester （DFHT Ⅱ）, with the redesigned of photo-electric conversion and signal acquirement module, an instrument has been developed. And comparing the experimental data from the instrument with those from a KLA-FHT D6, the discrepancy is less than 5%. It indicates that the instrument is suitable to perform ultra-low flying height measurement and satisfies the reauirement of magnetic heads manufacturing.
基金Project supported by the Innovation Foundation for Postgraduates in the National University of Defense Technology,China(Grant No. S090701)
文摘A seed laser oscillating at different frequencies is proved to have the potential to mitigate the stimulated Brillouin scattering（SBS） effect in a fiber amplifier,which may increase the emission power of a coherent beam combination（CBC） system greatly.In this study,a basic mathematical model describing the multi-wavelength CBC is proposed on the fundamentals of CBC.A useful method for estimating the combination effect and analysing the feasibility and the validity of the multi-wavelength coherent combination is provided.In the numerical analysis,accordant results with four-wavelength four-channel CBC experiments are obtained.Through calculations of some examples with certain spectra,the unanticipated excellent combination effect with a few frequencies involved is explained,and the dependence of the combination effect on the variance of the amplifier chain length and the channel number is clarified.
基金the Natural Science Foundation of Anhui Province (No. 99045332)
文摘This investigation developed a new method for determining metal complex's property containing the stepwise real absorptivity(epsilon) and stability constant (K-m). The correction equation of the multi-wavelength spectral absorption was established for the simultaneous determination of various complexes to give high accuracy for trace analysis. This method was more acceptable in theory and simpler in operation than the classical methods.
基金Project supported by the National Key Foundation for Exploring Scientific Instrument of China(2014YQ120351)National Natural Science Foundation of China(11504266,51702235,51871167)the Natural Science Foundation of Tianjin,China(17JCQNJC02300,18JCYBJC86200)。
文摘Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was prepared.In order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state density of the sample.At the same time,Nd^(3+)was introduced to transfer the energy to Ho^(3+)pumped with a 793 nm laser(Nd^(3+):4 F5/2,4 F3/2→Ho^(3+):5 I6).The effect of different halogen ion on the luminescent properties of the fluoride halide glass was compared.The results show that the luminescent intensity of infrared increases with the introduction of different halogen ions.By comparison,it is found that the sample with I-has the strongest luminescence of 1064 nm,2.0μm and 2.9μm.This is consistent with the calculated J-O intensity parameters.In addition,the 2.0 and 2.9μm emission of Ho^(3+)pumped with a 450 nm laser will not disappear.A mid-infrared sample with multi-wavelength excitation and multi-wavelength emission can be obtained.Nd^(3+)/Ho^(3+)co-doped fluoride halide glasses with 1064 nm,2.0μm and 2.9μm luminescence were prepared by melt quenching method.The luminescent mechanism and the energy transfer process between the two ions of Nd^(3+)/Ho^(3+)co-doped fluoride halide glass were studied.The J-O parameters,luminescence lifetime and absorption emission cross-sectional area of Ho^(3+)and Nd^(3+)were calculated,respectively.It is found that the value ofΩ2 in the glass matrix increases with the introduction of different halogen ions,whileΩ4 andΩ6 do not change obviously in different glass compositions.This is because the environment of the crystal field around the rare earth ions changes.The crystal phase and phonon energy of the sample were analyzed by X-ray diffraction pattern and a Fourier transform infrared spectrometer,respectively.Based on the above spectra and data(phonon energy is 634.71 cm-1),it can be predicted that Nd^(3+)/Ho^(3+)co-doped fluoride halide glass is a potential mid-infrared luminescent material.
基金National Natural Science Foundation of China(No.71801108)Natural Science Fund for Colleges and Universities of Anhui Province(No.KJ2017ZD32)。
文摘A method of measuring turbidity based on a multi-wavelength spectral sensor is proposed by using SFH4737 broad-band infrared LED,a multi-wavelength spectral sensor and independently developed data processing software.Combining multiple wavelength data from the sensor,the unitary and multivariate fitting models were constructed to investigate the relationship among light intensity information,absorbance and turbidity,respectively.The turbidity of the actual water bodies was measured separately by using proposed method and a commercially visible spectrophotometer.The independent-samples T test(p>0.05)showed that there was no significant difference between the method in this paper and the standard assay method.The method is simple and inexpensive,and can be applied to the rapid detection of water turbidity,providing a new way of industrial online measurement.
基金supported by the National Natural Science Foundation of China(Nos.61405096 and 61504058)the Introduction of Talent Research Fund of Nanjing University of Posts and Telecommunications(No.NY214158)+1 种基金the Open Fund of Laboratory of Solid State Micro-structures,Nanjing University(No.M28035)the Open Fund of State Key Laboratory of Transient Optics and Photonics,Chinese Academy of Sciences(No.SKLST201404)
文摘A tunable self-seeded multi-wavelength Brillouin-erbium fiber laser(BEFL) is proposed and demonstrated based on a few-mode fiber filter(FMFF) with varying temperature. The FMFF configuration is a section of uncoated few-mode fiber(FMF) sandwiched between two up-tapers. As the temperature varies from 25 °C to 125 °C, the transmission spectrum of FMFF moves towards the longer wavelength. The self-excited Brillouin pump is internally achieved by cascaded stimulated Brillouin scattering(SBS) in the single mode fiber(SMF). Then employing the FMFF temperature variation characteristics in the ring cavity fiber laser, the multi-wavelength of the output laser can be tuned, and the tunable range is about 8.0 nm. The generation of up to 15 Brillouin Stokes wavelengths with 16 d B optical signal-to-noise ratio(OSNR) is realized.
基金supported by the National Natural Science Foundation of China(No.62404098)the Natural Science Foundation of Jiangsu Province of China(No.BK20241196)the National Key Research and Development Program of China(Nos.2023YFB2806400,2021YFB2801902,and 2018YFB2201801)。
文摘In this Letter,we propose and experimentally demonstrate,to the best of our knowledge,a novel compact power-equalized multi-wavelength laser(MWL)source for optical I/O technology.This multi-wavelength distributed feedback(DFB)laser array is used to achieve simultaneous emission of multiple wavelengths with balanced output power and stable single-mode operation.The reconstruction equivalent chirp technique is used to design and fabricate theπ-phase shifted DFB laser array to achieve precise wavelength spacing.The power equalizers(PEs)are monolithically integrated in front of the laser unit to equalize the output power.The experimental results show that the wavelength spacing of the proposed eight-channel MWL is 100 G±4.38 G,and the maximum deviation of the intensity(MDOI)is 1.00 dB under a 25℃working environment.Compared with the traditional MWL structure,the wavelength spacing error is reduced from 0.32 to 0.035 nm,and the MODI is reduced from 3.8 to 1.0 dB.The output power exceeds 25 mW when the current injected into the semiconductor optical amplifier(SOA)is 150 mA.Besides,the relative intensity noise(RIN)of all wavelengths is below-138 dB/Hz,and clear 25 Gb/s non-return-to-zero(NRZ)eye diagrams are obtained for the eight wavelengths with the external lithium-niobate Mach-Zehnder modulator.The superior performance of the proposed MWL makes it a promising method for low-bit-error optical I/O links and high-density chip interconnection systems.
基金supported by National Key R&D Program of China(grant no.2022YFC2404201)the Chinese Academy of Sciences Project for Young Scientists in Basic Research(grant no.YSBR067).
文摘Conventional microscopes designed for submicron resolution in biological research are hindered by a limited field of view,typically around 1 mm.This restriction poses a challenge when attempting to simultaneously analyze various parts of a sample,such as different brain areas.In addition,conventional objective lenses struggle to perform consistently across the required range of wavelengths for brain imaging in vivo.Here we present a novel mesoscopic objective lens with an impressive field of view of 8 mm,a numerical aperture of 0.5,and a working wavelength range from 400 to 1000 nm.We achieved a resolution of 0.74μm in fluorescent beads imaging.The versatility of this lens was further demonstrated through high-quality images of mouse brain and kidney sections in a wide-field imaging system,a confocal laser scanning system,and a two-photon imaging system.This mesoscopic objective lens holds immense promise for advancing multi-wavelength imaging of large fields of view at high resolution.
基金supported by the National Natural Science Foundation of China(Grant Nos.12261131495,12075210,and 12275240)the Scientific Research and Development Fund of Zhejiang A&F University(Grant No.2021FR0009)。
文摘Because of the complexity and difficulty of realizing a multi-wavelength soliton state,reports on its internal dynamic characteristics are scarce.In this study,the switching and periodic soliton explosion processes of the multi-wavelength soliton state in a negative dispersion passively mode-locked fiber laser are realized.The generation of the multi-wavelength soliton state undergoes the process of noise,oscillation,and stable mode-locking,and the splitting and annihilation of solitons with different group velocities directly impact the generation and disappearance of three wavelengths.Positive and negative dispersion lead to different group velocities of solitons.The presence and displacement of solitons with different group velocities cause soliton collisions,which lead to soliton explosions.A soliton experiences relative phase oscillation,chaos,and oscillation,as well as convergence and separation before and after an explosion.With an increase in parameters related to pump power,single-soliton oscillation,multi-wavelength solitons,and chaos are found in experiments and simulations,proving the relevance and reliability between simulation and experimental results.This work promotes the dynamical study of multi-soliton collisions in nonlinear science and the development of chaos theory in multi-comb lasers.
基金supported by the National Natural Science Foundation of China(No.62305391)the Scientific Fund of the National University of Defense Technology(No.22-061)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20240126)
文摘This study demonstrates a kilowatt-level, spectrum-programmable, multi-wavelength fiber laser(MWFL) with wavelength, interval and intensity tunability. The central wavelength tuning range is 1060–1095 nm and the tunable number is controllable from 1 to 5. The wavelength interval can be tuned from 6 to 32 nm and the intensity of each channel can be adjusted independently. Maximum output power up to approximately 1100 W has been achieved by master oscillator power amplifier structures. We also investigate the wavelength evolution experimentally considering the difference of gain competition, which may give a primary reference for kW-level high-power MWFL spectral manipulation. To the best of our knowledge, this is the highest output power ever reported for a programmable MWFL. Benefiting from its high power and flexible spectral manipulability, the proposed MWFL has great potential in versatile applications such as nonlinear frequency conversion and spectroscopy.
基金supported by the Natural Science Foundation of Heilongjiang Province (No.JJ2019LH1509)National Natural Science Foundation of China (NSFC)(Nos.11704086 and61875043)+1 种基金Fundamental Research Funds for the Central Universities (No.3072020CF2519)111 Project of Harbin Engineering University (No.B13015)。
文摘We propose and demonstrate the cascaded multi-wavelength mode-locked erbium-doped fiber laser(EDFL) based on ultralong-period gratings(ULPGs) for the first time, to the best of our knowledge.Study found that the ULPG can be used as both a mode-locker for pulse shaping and a comb filter for multi-wavelength generation simultaneously.Using the dual-function of ULPG, three-, four-, five-, six-, and seven-wavelength mode-locked pulses are obtained in EDFL, seven of which are the largest number of wavelengths up to now.For the four-wavelength soliton pulses, their pulse width is about 7.8 ps.The maximum average output power and slope efficiency of these pulses are 8.4 m W and 2.03%, respectively.Besides the conventional pulses, hybrid soliton pulses composed of a four-wavelength pulse and single soliton are also observed.Finally, the effect of cavity dispersion on the multi-wavelength mode-locked pulses is also discussed.Our findings indicate that apart from common sensing and filtering, the ULPG may also possess attractive nonlinear pulse-shaping property for ultrafast photonics application.
