The whole brain imaging of animal models is a major challenge in the current optical field, especially in freely moving animals. In this paper, in vivo high-resolution and long-term characterization of zebrafish brain were achieved with optical coherence tomography (OCT) and photoacoustic microscopy (PAM). The combination of OCT and PAM demonstrated gratifying results in vivo characterization of adult zebrafish brain’s complex structure.
{"title":"Optical properties of adult zebrafish brain detected by optical coherence tomography and photoacoustic imaging in vivo","authors":"Yintao Lan, Weijian Gao, Mengyu Zhou, Jing Huang, Shuqi Gan, Yao Xu, Ting Lu, Yiqing Zhang, Jian Zhang","doi":"10.1117/12.2603247","DOIUrl":"https://doi.org/10.1117/12.2603247","url":null,"abstract":"The whole brain imaging of animal models is a major challenge in the current optical field, especially in freely moving animals. In this paper, in vivo high-resolution and long-term characterization of zebrafish brain were achieved with optical coherence tomography (OCT) and photoacoustic microscopy (PAM). The combination of OCT and PAM demonstrated gratifying results in vivo characterization of adult zebrafish brain’s complex structure.","PeriodicalId":330466,"journal":{"name":"Sixteenth National Conference on Laser Technology and Optoelectronics","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126977009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A wide wavelength tunable Er3+: ZBLAN passively mode-locked fiber laser operating in the 3 μm mid-infrared region with Ti3C2Tx as a saturable absorber has been presented. The wavelength was selected by rotating the blazed grating. The fiber laser can achieve stable continuous-wave mode-locked state in the wide wavelength tuning range of 118.6 nm (2709 nm~2827.6 nm) with a repetition frequency of 28.3 MHz. When the launched pump power is 1.77 W, a stable mode-locked pulse with a maximum output power of 137.4 mW can be obtained at 2786 nm, and the corresponding single pulse energy is ~4.9 nJ. However, the pulse duration was not measured by the autocorrelator due to the limited output power. To the best of our knowledge, this is a passively mode-locked fiber laser at ~3 μm with the largest tuning range based on a saturable absorber. The presented widely wavelength tunable laser is a stable seed source for applications in laser medical treatment, spectroscopy and supercontinuum generation.
{"title":"118 nm-wavelength-tunable Er3+-doped ZBLAN passively mode-locked fiber laser","authors":"P. Chang, Chenchen Wang, Qi Wu, Jianfeng Li","doi":"10.1117/12.2603061","DOIUrl":"https://doi.org/10.1117/12.2603061","url":null,"abstract":"A wide wavelength tunable Er3+: ZBLAN passively mode-locked fiber laser operating in the 3 μm mid-infrared region with Ti3C2Tx as a saturable absorber has been presented. The wavelength was selected by rotating the blazed grating. The fiber laser can achieve stable continuous-wave mode-locked state in the wide wavelength tuning range of 118.6 nm (2709 nm~2827.6 nm) with a repetition frequency of 28.3 MHz. When the launched pump power is 1.77 W, a stable mode-locked pulse with a maximum output power of 137.4 mW can be obtained at 2786 nm, and the corresponding single pulse energy is ~4.9 nJ. However, the pulse duration was not measured by the autocorrelator due to the limited output power. To the best of our knowledge, this is a passively mode-locked fiber laser at ~3 μm with the largest tuning range based on a saturable absorber. The presented widely wavelength tunable laser is a stable seed source for applications in laser medical treatment, spectroscopy and supercontinuum generation.","PeriodicalId":330466,"journal":{"name":"Sixteenth National Conference on Laser Technology and Optoelectronics","volume":"159 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116299151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Radially symmetric Airy-like beams have the ability to autofocus abruptly, which leads to a wild application, for instance, particle manipulation and light bullets. On the basic of the theory of 1D self-accelerating Airy beam, this thesis starts the research on propagation property of Airy-like self-focusing pin-like beams. Based on the theory of stationary phase calculation, we obtain the trajectory function of Airy-like beams and dynamics of the optical beam before the focus and beyond. With the method of beam split-step Fourier method, we theoretically analyze the transverse and longitude amplitude trending of this optical beam. It turns out that Airy-like beam propose an abruptly autofocusing property like circularly symmetric Airy beam, its propagation follows a parabolic trajectory and tends to focus on the axial; after focusing, the optical beam morphs into a Bessel-like beam, its main lobe size decreases during the propagation and finally becomes pin-like.
{"title":"Study on propagation property of self-focusing pin-like beams","authors":"Kaichen Pi, Y.-G. Kuang, Yuanshen Xiao, Xiang Zhang","doi":"10.1117/12.2602872","DOIUrl":"https://doi.org/10.1117/12.2602872","url":null,"abstract":"Radially symmetric Airy-like beams have the ability to autofocus abruptly, which leads to a wild application, for instance, particle manipulation and light bullets. On the basic of the theory of 1D self-accelerating Airy beam, this thesis starts the research on propagation property of Airy-like self-focusing pin-like beams. Based on the theory of stationary phase calculation, we obtain the trajectory function of Airy-like beams and dynamics of the optical beam before the focus and beyond. With the method of beam split-step Fourier method, we theoretically analyze the transverse and longitude amplitude trending of this optical beam. It turns out that Airy-like beam propose an abruptly autofocusing property like circularly symmetric Airy beam, its propagation follows a parabolic trajectory and tends to focus on the axial; after focusing, the optical beam morphs into a Bessel-like beam, its main lobe size decreases during the propagation and finally becomes pin-like.","PeriodicalId":330466,"journal":{"name":"Sixteenth National Conference on Laser Technology and Optoelectronics","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115464440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Huang, Leshi Shu, Qi Zhou, P. Jiang, Geng Shaoning
The root hump defect is easy to appear in the process of high power laser welding. Through the observation of welding experiment, it is found that there is obvious correlation between root hump defect and the character of keyhole and molten pool. Therefore, this paper proposes a method to monitor the root hump defect by identifying the keyhole and molten pool features in the welding process. In this method, image sensing technology and machine vision method are used to analyze and extract the keyhole and weld pool information in real time. The BP neural network algorithm is used to classify the welding states. It is found that adding the feature of weld pool length as input will greatly improve the recognition accuracy of the model.
{"title":"Root hump defect monitoring of high power fiber laser thick plate welding based on the character of keyhole and molten pool","authors":"D. Huang, Leshi Shu, Qi Zhou, P. Jiang, Geng Shaoning","doi":"10.1117/12.2602992","DOIUrl":"https://doi.org/10.1117/12.2602992","url":null,"abstract":"The root hump defect is easy to appear in the process of high power laser welding. Through the observation of welding experiment, it is found that there is obvious correlation between root hump defect and the character of keyhole and molten pool. Therefore, this paper proposes a method to monitor the root hump defect by identifying the keyhole and molten pool features in the welding process. In this method, image sensing technology and machine vision method are used to analyze and extract the keyhole and weld pool information in real time. The BP neural network algorithm is used to classify the welding states. It is found that adding the feature of weld pool length as input will greatly improve the recognition accuracy of the model.","PeriodicalId":330466,"journal":{"name":"Sixteenth National Conference on Laser Technology and Optoelectronics","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115701200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The influence of pulse width on relativistic motion and full spatial characteristics of radiation generated from electron oscillations driven by circularly polarized intense femtosecond laser pulses have been investigated theoretically and numerically using a single electron model. The electron trajectories show asymmetric spiral patterns for few-cycle laser pulse which do not resemble with twofold symmetric spiral patterns in the multi-cycle laser pulse. It is discovered that the patterns of the full spatial distribution of electron emission are of the shape resembling a flower of calla for few-cycle laser pulse and the radiated power per unit solid angle show a horn like shape directed toward the direction of the laser pulses propagation with a narrower divergence for multi-cycle laser pulse.
{"title":"Influence of different pulse width on electron emission characteristics driven by circularly polarized intense laser","authors":"Lingxiao Li, Mengyuan Tao, P. Yu, Youwei Tian","doi":"10.1117/12.2600833","DOIUrl":"https://doi.org/10.1117/12.2600833","url":null,"abstract":"The influence of pulse width on relativistic motion and full spatial characteristics of radiation generated from electron oscillations driven by circularly polarized intense femtosecond laser pulses have been investigated theoretically and numerically using a single electron model. The electron trajectories show asymmetric spiral patterns for few-cycle laser pulse which do not resemble with twofold symmetric spiral patterns in the multi-cycle laser pulse. It is discovered that the patterns of the full spatial distribution of electron emission are of the shape resembling a flower of calla for few-cycle laser pulse and the radiated power per unit solid angle show a horn like shape directed toward the direction of the laser pulses propagation with a narrower divergence for multi-cycle laser pulse.","PeriodicalId":330466,"journal":{"name":"Sixteenth National Conference on Laser Technology and Optoelectronics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123924921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Huaimiao Sun, Zejun Li, Zhanda Zhu, Yongling Hui, H. Lei, Qiang Li
LD pumped erbium glass passively Q-switched 1.5μm microchip laser is a research hotspot in laser ranging and imaging application. The high repetition rate microchip laser has serious thermal effect problem, so it is difficult to work stably for a long time. This paper reports a passively Q-switched 1535nm laser with erbium-ytterbium co-doped phosphate glass using double-ended adhesive-free bonding technology. The laser combines YAG crystal, Er3+/Yb3+: glass and Co2+[/sup : MgAl2O4 by bonding to improve the thermal effect of the laser. At the same time, by optimizing the size of the pump light spot, the initial transmittance T0 of the saturable absorber and the reflectivity R of the output mirror, the utilization efficiency of the pump light is improved and the influence of thermal effect is further reduced. The results show that the laser output with the repetition rate of 1kHz, the single pulse energy of 40μJ, pulse width of 8ns, peak power of 5kW, beam quality of 1.4, can output stably for a long time.
{"title":"1kHz, Er3+/Yb3+: glass passively Q-switched microchip laser with long time stable operation","authors":"Huaimiao Sun, Zejun Li, Zhanda Zhu, Yongling Hui, H. Lei, Qiang Li","doi":"10.1117/12.2602899","DOIUrl":"https://doi.org/10.1117/12.2602899","url":null,"abstract":"LD pumped erbium glass passively Q-switched 1.5μm microchip laser is a research hotspot in laser ranging and imaging application. The high repetition rate microchip laser has serious thermal effect problem, so it is difficult to work stably for a long time. This paper reports a passively Q-switched 1535nm laser with erbium-ytterbium co-doped phosphate glass using double-ended adhesive-free bonding technology. The laser combines YAG crystal, Er3+/Yb3+: glass and Co2+[/sup : MgAl2O4 by bonding to improve the thermal effect of the laser. At the same time, by optimizing the size of the pump light spot, the initial transmittance T0 of the saturable absorber and the reflectivity R of the output mirror, the utilization efficiency of the pump light is improved and the influence of thermal effect is further reduced. The results show that the laser output with the repetition rate of 1kHz, the single pulse energy of 40μJ, pulse width of 8ns, peak power of 5kW, beam quality of 1.4, can output stably for a long time.","PeriodicalId":330466,"journal":{"name":"Sixteenth National Conference on Laser Technology and Optoelectronics","volume":"109 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115158958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhang Jingtao, Yongtao Deng, Tao Yuliang, Ao-you Wang, Long Wang, Xu Li
The large dynamic range of the satellite-borne laser altimeter receiver is a necessary condition for obtaining high-precision ranging values. The upper and lower limits of the dynamic range reflect the ecological adaptability of the altimeter. The power of the echo signal is given in the performance of the altimeter, atmospheric reflection, and target surface reflection. If the waveform of the strong echo signal with high ground reflectivity and specular reflection appears saturated, broadened and distorted, it will interfere with the extraction of helpful information during waveform inversion and affect the accuracy of ranging. Although the waveform saturation can be corrected by the mid-to-late GLAS correction method, this paper proposes a high-sensitivity signal detection technology for a space borne laser altimeter with a large dynamic range, which is suitable for laser altimeters with any linear detection system without waveform saturation. The correction can obtain a larger dynamic range, and the mechanism analysis does not require the dual-channel gain method to obtain a larger dynamic range. In this paper, the method of combining Bessel filter and adjustable gain amplifier is utilized to optimize the design bandwidth to suppress noise, and the sensitivity is not less than 5.1nW. If the parameters are not adjusted, the dynamic range is not less than 33.7dB; if the parameters are adjusted, the sensitivity is not Below 1nW, the dynamic range is about 73.9dB. Through the ground vacuum environment test, under the condition of high signal-to-noise ratio, the ranging accuracy is better than 0.08m; when the signal-to-noise ratio is not less than 8, the ranging accuracy is not less than 0.4m.
{"title":"Large dynamic range and high sensitive signal detection technology of spaceborne laser altimeter","authors":"Zhang Jingtao, Yongtao Deng, Tao Yuliang, Ao-you Wang, Long Wang, Xu Li","doi":"10.1117/12.2603037","DOIUrl":"https://doi.org/10.1117/12.2603037","url":null,"abstract":"The large dynamic range of the satellite-borne laser altimeter receiver is a necessary condition for obtaining high-precision ranging values. The upper and lower limits of the dynamic range reflect the ecological adaptability of the altimeter. The power of the echo signal is given in the performance of the altimeter, atmospheric reflection, and target surface reflection. If the waveform of the strong echo signal with high ground reflectivity and specular reflection appears saturated, broadened and distorted, it will interfere with the extraction of helpful information during waveform inversion and affect the accuracy of ranging. Although the waveform saturation can be corrected by the mid-to-late GLAS correction method, this paper proposes a high-sensitivity signal detection technology for a space borne laser altimeter with a large dynamic range, which is suitable for laser altimeters with any linear detection system without waveform saturation. The correction can obtain a larger dynamic range, and the mechanism analysis does not require the dual-channel gain method to obtain a larger dynamic range. In this paper, the method of combining Bessel filter and adjustable gain amplifier is utilized to optimize the design bandwidth to suppress noise, and the sensitivity is not less than 5.1nW. If the parameters are not adjusted, the dynamic range is not less than 33.7dB; if the parameters are adjusted, the sensitivity is not Below 1nW, the dynamic range is about 73.9dB. Through the ground vacuum environment test, under the condition of high signal-to-noise ratio, the ranging accuracy is better than 0.08m; when the signal-to-noise ratio is not less than 8, the ranging accuracy is not less than 0.4m.","PeriodicalId":330466,"journal":{"name":"Sixteenth National Conference on Laser Technology and Optoelectronics","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124362139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jie Wang, L. Bai, Tianjiao Zhang, Q. Lv, Chaofan Xue
The ultraviolet radiation generated by NO transition in the shock layer of hypersonic vehicle provides an important basis for target detection and recognition. In this paper, direct simulation Monte Carlo (DSMC) method is used to simulate the high temperature flow field of the Apollo aircraft. Based on the temperature, pressure, and mass fraction, SPECAIR software is used to calculate the NO(γ) spectral absorption coefficient, and combined with the line of sight (LOS) method, the ultraviolet radiation produced by the NO(γ) transition along the stagnation line at different heights is calculated. Based on the wall heat flux, the wall energy conservation equation is used to calculate the wall temperature, combined with the Planck's law to calculate the wall radiation, and the influence of the wall catalytic effect on the ultraviolet radiation is studied. The results show that with the increase of the height, the gas pressure and temperature decrease obviously, and the ultraviolet radiation from NO(γ) transition decreases. The wall heat flux calculated by the wall catalytic model is very different. The choice of the wall catalytic model is particularly important when studying the influence of the wall radiation on the ultraviolet radiation.
{"title":"Ultraviolet radiation characteristics of NO in shock layer of hypersonic vehicle","authors":"Jie Wang, L. Bai, Tianjiao Zhang, Q. Lv, Chaofan Xue","doi":"10.1117/12.2601819","DOIUrl":"https://doi.org/10.1117/12.2601819","url":null,"abstract":"The ultraviolet radiation generated by NO transition in the shock layer of hypersonic vehicle provides an important basis for target detection and recognition. In this paper, direct simulation Monte Carlo (DSMC) method is used to simulate the high temperature flow field of the Apollo aircraft. Based on the temperature, pressure, and mass fraction, SPECAIR software is used to calculate the NO(γ) spectral absorption coefficient, and combined with the line of sight (LOS) method, the ultraviolet radiation produced by the NO(γ) transition along the stagnation line at different heights is calculated. Based on the wall heat flux, the wall energy conservation equation is used to calculate the wall temperature, combined with the Planck's law to calculate the wall radiation, and the influence of the wall catalytic effect on the ultraviolet radiation is studied. The results show that with the increase of the height, the gas pressure and temperature decrease obviously, and the ultraviolet radiation from NO(γ) transition decreases. The wall heat flux calculated by the wall catalytic model is very different. The choice of the wall catalytic model is particularly important when studying the influence of the wall radiation on the ultraviolet radiation.","PeriodicalId":330466,"journal":{"name":"Sixteenth National Conference on Laser Technology and Optoelectronics","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116858332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jia-Chen Liu, Yongzhen Huang, Youzeng Hao, Jiliang Wu, Ke Yang, Yuede Yang, J. Xiao
A numerical scheme for calculating phase noise is proposed for hybrid square-rectangular semiconductor lasers. By establishing a two-section single-mode rate equation model driven by Langevin noise sources and considering the nonlinear gain effect, we numerically studied the phase noise characteristics and linewidth of the hybrid-cavity laser. The time-varying spectra of carrier density, photon density and phase are simulated and the frequency spectra of phase noise are presented with the help of the fast Fourier transform. With the increase of the bias current, the frequency noise has an obvious downward trend and a narrower linewidth is obtained. The linewidth of the hybrid square-rectangular laser is calculated according to the phase noise at low frequency. The simulated linewidth of the hybrid-cavity semiconductor laser is 0.36 MHz at the linewidth enhancement factor of 3 when the square microcavity bias current is 20 mA and the FP cavity bias current is 100 mA.
{"title":"Numerical simulation of phase noise in hybrid square-rectangular lasers","authors":"Jia-Chen Liu, Yongzhen Huang, Youzeng Hao, Jiliang Wu, Ke Yang, Yuede Yang, J. Xiao","doi":"10.1117/12.2603057","DOIUrl":"https://doi.org/10.1117/12.2603057","url":null,"abstract":"A numerical scheme for calculating phase noise is proposed for hybrid square-rectangular semiconductor lasers. By establishing a two-section single-mode rate equation model driven by Langevin noise sources and considering the nonlinear gain effect, we numerically studied the phase noise characteristics and linewidth of the hybrid-cavity laser. The time-varying spectra of carrier density, photon density and phase are simulated and the frequency spectra of phase noise are presented with the help of the fast Fourier transform. With the increase of the bias current, the frequency noise has an obvious downward trend and a narrower linewidth is obtained. The linewidth of the hybrid square-rectangular laser is calculated according to the phase noise at low frequency. The simulated linewidth of the hybrid-cavity semiconductor laser is 0.36 MHz at the linewidth enhancement factor of 3 when the square microcavity bias current is 20 mA and the FP cavity bias current is 100 mA.","PeriodicalId":330466,"journal":{"name":"Sixteenth National Conference on Laser Technology and Optoelectronics","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116889869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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