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2020
Volume: 18 Issue 12
20 Article(s)
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Research Articles
Biophotonics
Optical-resolution photoacoustic microscopy continually monitors macrophages activities of acute inflammation in vivo
Fei Duan, Haosong Ma, Jinde Zhang, Shi Li, Honghui Li, Zhiyou Wu, Fengqiu Hong, Lüming Zeng, and Liming Nie
Photoacoustic imaging has been developed to image the immune study at the macro scale. Macrophages play diverse roles in the acute response to infection and tissue repair. However, macrophages activities in acute inflammation at the microscopic level still remain challenging. In this work, we proposed optical-resolution photoacoustic microscopy to promptly monitor the labeled macrophages activities in normal and inflammatory groups. The result showed that many labeled macrophages emerged around the vessels firstly, then exuded into tissues, and finally disappeared in the inflammatory group injected with labeled macrophages. In summary, our method allows us to exactly image and track the immune cells of inflammatory diseases.Photoacoustic imaging has been developed to image the immune study at the macro scale. Macrophages play diverse roles in the acute response to infection and tissue repair. However, macrophages activities in acute inflammation at the microscopic level still remain challenging. In this work, we proposed optical-resolution photoacoustic microscopy to promptly monitor the labeled macrophages activities in normal and inflammatory groups. The result showed that many labeled macrophages emerged around the vessels firstly, then exuded into tissues, and finally disappeared in the inflammatory group injected with labeled macrophages. In summary, our method allows us to exactly image and track the immune cells of inflammatory diseases..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121701 (2020)
Molecular vibrational imaging by stimulated Raman scattering microscopy: principles and applications [Invited] | On the Cover
Yasuyuki Ozeki
The recent development of stimulated Raman scattering (SRS) microscopy allows for highly sensitive biological imaging with molecular vibrational contrast, opening up a variety of applications including label-free imaging, metabolic imaging, and super-multiplex imaging. This paper introduces the principle of SRS microscopy and the methods of multicolor SRS imaging and describes an overview of biomedical applications.The recent development of stimulated Raman scattering (SRS) microscopy allows for highly sensitive biological imaging with molecular vibrational contrast, opening up a variety of applications including label-free imaging, metabolic imaging, and super-multiplex imaging. This paper introduces the principle of SRS microscopy and the methods of multicolor SRS imaging and describes an overview of biomedical applications..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121702 (2020)
Design and implementation of the galvanometer scanning system for reflectance confocal and stimulated Raman scattering microscopy
Fangyu Wang, Yuhao Yuan, Qiang Sun, Ming Dai, Li Ai, and Fake Lu
We report on two strategies to design and implement the galvanometer-based laser-scanning mechanisms for the realization of reflectance confocal microscopy (RCM) and stimulated Raman scattering (SRS) microscopy systems. The RCM system uses a resonant galvanometer scanner driven by a home-built field-programmable gate array circuit with a novel dual-trigger mode and a home-built high-speed data acquisition card. The SRS system uses linear galvanometers with commercially available modules. We demonstrate video-rate high-resolution imaging at 11 frames per second of in vivo human skin with the RCM system and label-free biomolecular imaging of cancer cells with the SRS system. A comparison of the two strategies for controlling galvanometer scanners provides scientific and technical reference for future design and commercialization of various laser-scanning microscopes using galvanometers.We report on two strategies to design and implement the galvanometer-based laser-scanning mechanisms for the realization of reflectance confocal microscopy (RCM) and stimulated Raman scattering (SRS) microscopy systems. The RCM system uses a resonant galvanometer scanner driven by a home-built field-programmable gate array circuit with a novel dual-trigger mode and a home-built high-speed data acquisition card. The SRS system uses linear galvanometers with commercially available modules. We demonstrate video-rate high-resolution imaging at 11 frames per second of in vivo human skin with the RCM system and label-free biomolecular imaging of cancer cells with the SRS system. A comparison of the two strategies for controlling galvanometer scanners provides scientific and technical reference for future design and commercialization of various laser-scanning microscopes using galvanometers..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121703 (2020)
Feasibility study for bone health assessment based on photoacoustic imaging method
Ting Feng, Yunhao Zhu, Yejing Xie, Dean Ta, Jie Yuan, and Qian Cheng
This study investigated the feasibility of photoacoustic (PA) imaging of bone and characterization of bone features. By conducting the experiments on bovine femoral heads ex vivo, the light and ultrasonic penetration in bones was studied, together with the depth of PA imaging and measurement in bones. Then, the possibility of three-dimensional (3D) PA imaging of bones by raster scanning of the focusing transducer was studied. The micro-computerized tomography images of the bovine ribs with and without ethylenediaminetetraacetic acid (EDTA) treatment indicated that the 3D PA images could present the changes of bone microstructure resulting from the EDTA treatment. By using PA spectral analysis, the bone samples with and without the treatment of EDTA solution can be distinguished, and the microstructures can be characterized. This study was based on the bovine bone whose size is comparable to human bones, suggesting that PA technology can be used as a novel bone diagnostic technique.This study investigated the feasibility of photoacoustic (PA) imaging of bone and characterization of bone features. By conducting the experiments on bovine femoral heads ex vivo, the light and ultrasonic penetration in bones was studied, together with the depth of PA imaging and measurement in bones. Then, the possibility of three-dimensional (3D) PA imaging of bones by raster scanning of the focusing transducer was studied. The micro-computerized tomography images of the bovine ribs with and without ethylenediaminetetraacetic acid (EDTA) treatment indicated that the 3D PA images could present the changes of bone microstructure resulting from the EDTA treatment. By using PA spectral analysis, the bone samples with and without the treatment of EDTA solution can be distinguished, and the microstructures can be characterized. This study was based on the bovine bone whose size is comparable to human bones, suggesting that PA technology can be used as a novel bone diagnostic technique..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121704 (2020)
Deep learning virtual colorful lens-free on-chip microscopy
Hua Shen, and Jinming Gao
Currently, it is generally known that lens-free holographic microscopy, which has no imaging lens, can realize a large field-of-view imaging with a low-cost setup. However, in order to obtain colorful images, traditional lens-free holographic microscopy should utilize at least three quasi-chromatic light sources of discrete wavelengths, such as red LED, green LED, and blue LED. Here, we present a virtual colorization by deep learning methods to transfer a gray lens-free microscopy image into a colorful image. Through pairs of images, i.e., grayscale lens-free microscopy images under green LED at 550 nm illumination and colorful bright-field microscopy images, a generative adversarial network (GAN) is trained, and its effectiveness of virtual colorization is proved by applying it to hematoxylin and eosin stained pathological tissue samples imaging. Our computational virtual colorization method might strengthen the monochromatic illumination lens-free microscopy in medical pathology applications and label staining biomedical research.Currently, it is generally known that lens-free holographic microscopy, which has no imaging lens, can realize a large field-of-view imaging with a low-cost setup. However, in order to obtain colorful images, traditional lens-free holographic microscopy should utilize at least three quasi-chromatic light sources of discrete wavelengths, such as red LED, green LED, and blue LED. Here, we present a virtual colorization by deep learning methods to transfer a gray lens-free microscopy image into a colorful image. Through pairs of images, i.e., grayscale lens-free microscopy images under green LED at 550 nm illumination and colorful bright-field microscopy images, a generative adversarial network (GAN) is trained, and its effectiveness of virtual colorization is proved by applying it to hematoxylin and eosin stained pathological tissue samples imaging. Our computational virtual colorization method might strengthen the monochromatic illumination lens-free microscopy in medical pathology applications and label staining biomedical research..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121705 (2020)
Diffraction, Gratings, and Holography
Multiple super-resolution imaging in the second band of gradient lattice spacing photonic crystal flat lens
Jie Sheng, Jianlan Xie, and Jianjun Liu
Based on the triangular lattice two-dimensional photonic crystal (PC), the lattice spacing along the transverse direction to propagation is altered, and a gradient PC (GPC) flat lens is designed. The band structures and equal frequency curves of the GPC are calculated; then, the imaging mechanism and feasibility are analyzed. The imaging characteristics of the GPC flat lens are investigated. It is observed that the GPC can achieve multiple types of super-resolution imaging for the point source. This GPC lens is allowed to be applied to imaging and other fields such as filtering and sensing.Based on the triangular lattice two-dimensional photonic crystal (PC), the lattice spacing along the transverse direction to propagation is altered, and a gradient PC (GPC) flat lens is designed. The band structures and equal frequency curves of the GPC are calculated; then, the imaging mechanism and feasibility are analyzed. The imaging characteristics of the GPC flat lens are investigated. It is observed that the GPC can achieve multiple types of super-resolution imaging for the point source. This GPC lens is allowed to be applied to imaging and other fields such as filtering and sensing..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 120501 (2020)
Fiber Optics and Optical Communications
Near-navigation-grade interferometric fiber optic gyroscope with an integrated optical chip
Kejun Shang, Ming Lei, Qiang Xiang, Yonglin Na, Lizhe Zhang, and Huaiyong Yu
We present a near-navigation-grade interferometric fiber optic gyroscope (IFOG) based on an integrated optical chip. The chip comprises a light source, a photodiode, and a 3 dB coupler within an area of 48 mm2. By interrogating with an integrated optical modulator and a small-diameter sensing coil, the IFOG is realized. This allows for a significant reduction in size, weight, power consumption, and cost. Preliminary performance data of a gyro prototype exhibits 0.018 deg/h bias instability.We present a near-navigation-grade interferometric fiber optic gyroscope (IFOG) based on an integrated optical chip. The chip comprises a light source, a photodiode, and a 3 dB coupler within an area of 48 mm2. By interrogating with an integrated optical modulator and a small-diameter sensing coil, the IFOG is realized. This allows for a significant reduction in size, weight, power consumption, and cost. Preliminary performance data of a gyro prototype exhibits 0.018 deg/h bias instability..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 120601 (2020)
Single scattering turbulence model based on the division of effective scattering volume for ultraviolet communication
Tao Shan, Jianshe Ma, Tianfeng Wu, Zanqiu Shen, and Ping Su
In this Letter, a single scattering turbulence model in a narrow beam case for ultraviolet (UV) communication is proposed based on the division of the effective scattering volume. This model takes the variation of atmospheric scattering, absorption, and turbulence in different paths into account. Meanwhile, the applicable transceiver configurations of this model are provided by analyzing path loss error caused by the single scattering assumption in the UV channel. Furthermore, we investigate the effect of turbulence on the probability density function of the arriving power in both coplanar and non-coplanar scenarios. The averaging effect of multipath propagation on the arriving power’s fluctuations is presented. Then, the bit-error-rate performance is also studied. This work provides an efficient way for UV turbulence channel estimation.In this Letter, a single scattering turbulence model in a narrow beam case for ultraviolet (UV) communication is proposed based on the division of the effective scattering volume. This model takes the variation of atmospheric scattering, absorption, and turbulence in different paths into account. Meanwhile, the applicable transceiver configurations of this model are provided by analyzing path loss error caused by the single scattering assumption in the UV channel. Furthermore, we investigate the effect of turbulence on the probability density function of the arriving power in both coplanar and non-coplanar scenarios. The averaging effect of multipath propagation on the arriving power’s fluctuations is presented. Then, the bit-error-rate performance is also studied. This work provides an efficient way for UV turbulence channel estimation..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 120602 (2020)
Lasers, Optical Amplifiers, and Laser Optics
Cylindrical vector beam rotary Nd:YAG disk laser with birefringent crystal
Sanbin Chen, Jianlang Li, and Ken-Ichi Ueda
A rotating neodymium-doped yttrium aluminum garnet (Nd:YAG) disk laser resonator for efficiently generating vector beams with azimuthal and radial polarization is demonstrated. In the study, the laser crystal rotary for thermal alleviation and polarization discrimination uses c-cut ytterbium vanadate (YVO4). The laser output could be switched between azimuthal and radial polarizations by simply adjusting the cavity length. The laser power reached 4.38 W and 4.64 W for azimuthally and radially polarized beams at the slope efficiencies of 45.3% and 48.5%, respectively. Our study proved that an efficient, high-power vector rotary disk laser would be realistic.A rotating neodymium-doped yttrium aluminum garnet (Nd:YAG) disk laser resonator for efficiently generating vector beams with azimuthal and radial polarization is demonstrated. In the study, the laser crystal rotary for thermal alleviation and polarization discrimination uses c-cut ytterbium vanadate (YVO4). The laser output could be switched between azimuthal and radial polarizations by simply adjusting the cavity length. The laser power reached 4.38 W and 4.64 W for azimuthally and radially polarized beams at the slope efficiencies of 45.3% and 48.5%, respectively. Our study proved that an efficient, high-power vector rotary disk laser would be realistic..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121401 (2020)
Simultaneous generation of controllable double white light lasers by focusing an intense femtosecond laser pulse in air
Yaoxiang Liu, Tie-Jun Wang, Na Chen, Hao Guo, Haiyi Sun, Lu Zhang, Zheng Qi, Yuxin Leng, Zhanshan Wang, and Ruxin Li
We report on a simultaneous generation of double white light lasers through filamentation by focusing a femtosecond laser pulse. The appearance of the two white light lasers can be controlled by tilting the focusing lens. The spectral bandwidth and the pulse energy of the double white light lasers were controlled by tuning laser filamenting pulse energy and polarization. Two white light lasers with pulse energies of 1.54 mJ and 1.84 mJ, respectively, were generated with the pump laser energy of 7.43 mJ. Besides being beneficial in understanding the multiple white light lasers generation process through multiple filamentation and its control, the results are also valuable for white light laser-based applications.We report on a simultaneous generation of double white light lasers through filamentation by focusing a femtosecond laser pulse. The appearance of the two white light lasers can be controlled by tilting the focusing lens. The spectral bandwidth and the pulse energy of the double white light lasers were controlled by tuning laser filamenting pulse energy and polarization. Two white light lasers with pulse energies of 1.54 mJ and 1.84 mJ, respectively, were generated with the pump laser energy of 7.43 mJ. Besides being beneficial in understanding the multiple white light lasers generation process through multiple filamentation and its control, the results are also valuable for white light laser-based applications..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121402 (2020)
Noise-like pulse with a 690 fs pedestal generated from a nonlinear Yb-doped fiber amplification system | Editors' Pick
Zexin Zhang, Jinrong Tian, Changxing Xu, Runqin Xu, Youshuo Cui, Bihui Zhuang, and Yanrong Song
Noise-like pulses having a pedestal of 690 fs and a spike of 59.6 fs were generated in a nonlinear Yb-doped fiber amplification system. The seed source is a mode-locked Yb-doped fiber laser by nonlinear polarization rotation, and dissipative soliton pulses were obtained in it. Then, the dissipative soliton pulses passed through a 7.6 m dispersive fiber to enhance the dispersion and nonlinearity. Further on, the dissipative soliton pulses were launched into a Yb-doped fiber nonlinear amplifier, and stable noise-like pulses with a pedestal of 6.26 ps and a spike of 227 fs were achieved. Finally, by a grating pair, the pedestal and spike of the noise-like pulses were effectively compressed to 690 fs and 59.6 fs, respectively. To the best of our knowledge, this is the shortest pedestal demonstrated in noise-like pulses operating at 1 μm.Noise-like pulses having a pedestal of 690 fs and a spike of 59.6 fs were generated in a nonlinear Yb-doped fiber amplification system. The seed source is a mode-locked Yb-doped fiber laser by nonlinear polarization rotation, and dissipative soliton pulses were obtained in it. Then, the dissipative soliton pulses passed through a 7.6 m dispersive fiber to enhance the dispersion and nonlinearity. Further on, the dissipative soliton pulses were launched into a Yb-doped fiber nonlinear amplifier, and stable noise-like pulses with a pedestal of 6.26 ps and a spike of 227 fs were achieved. Finally, by a grating pair, the pedestal and spike of the noise-like pulses were effectively compressed to 690 fs and 59.6 fs, respectively. To the best of our knowledge, this is the shortest pedestal demonstrated in noise-like pulses operating at 1 μm..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121403 (2020)
Light-matter Interaction
Picosecond burst pulse machining with temporal energy modulation [Invited] | Editors' Pick
Akinao Nakamura, Tomoki Mizuta, Yasuhiko Shimotsuma, Masaaki Sakakura, Tomohito Otobe, Masahiro Shimizu, and Kiyotaka Miura
Suppression of stress and crack generation during picosecond laser processing in transparent brittle materials such as glass was successfully demonstrated by a picosecond laser pulse with temporal energy modulation. The origin of deterioration in processing accuracy could be interpreted in terms of the discontinuous movement of plasma in the vicinity of the focus. To reveal the effectiveness of the temporal energy modulation for smooth machining, such plasma motion was simulated by the finite-difference time-domain method. Furthermore, photoinduced birefringence was observed using a high-speed polarization camera.Suppression of stress and crack generation during picosecond laser processing in transparent brittle materials such as glass was successfully demonstrated by a picosecond laser pulse with temporal energy modulation. The origin of deterioration in processing accuracy could be interpreted in terms of the discontinuous movement of plasma in the vicinity of the focus. To reveal the effectiveness of the temporal energy modulation for smooth machining, such plasma motion was simulated by the finite-difference time-domain method. Furthermore, photoinduced birefringence was observed using a high-speed polarization camera..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 123801 (2020)
Microwave Photonics
Ultra-wideband signal acquisition by use of channel-interleaved photonic analog-to-digital converter under the assistance of dilated fully convolutional network
Rui Wang, Shaofu Xu, Jianping Chen, and Weiwen Zou
We demonstrate a photonic architecture to enable the separation of ultra-wideband signals. The architecture consists of a channel-interleaved photonic analog-to-digital converter (PADC) and a dilated fully convolutional network (DFCN). The aim of the PADC is to perform ultra-wideband signal acquisition, which introduces the mixing of signals between different frequency bands. To alleviate the interference among wideband signals, the DFCN is applied to reconstruct the waveform of the target signal from the ultra-wideband mixed signals in the time domain. The channel-interleaved PADC provides a wide spectrum reception capability. Relying on the DFCN reconstruction algorithm, the ultra-wideband signals, which are originally mixed up, are effectively separated. Additionally, experimental results show that the DFCN reconstruction algorithm improves the average bit error rate by nearly three orders of magnitude compared with that without the algorithm.We demonstrate a photonic architecture to enable the separation of ultra-wideband signals. The architecture consists of a channel-interleaved photonic analog-to-digital converter (PADC) and a dilated fully convolutional network (DFCN). The aim of the PADC is to perform ultra-wideband signal acquisition, which introduces the mixing of signals between different frequency bands. To alleviate the interference among wideband signals, the DFCN is applied to reconstruct the waveform of the target signal from the ultra-wideband mixed signals in the time domain. The channel-interleaved PADC provides a wide spectrum reception capability. Relying on the DFCN reconstruction algorithm, the ultra-wideband signals, which are originally mixed up, are effectively separated. Additionally, experimental results show that the DFCN reconstruction algorithm improves the average bit error rate by nearly three orders of magnitude compared with that without the algorithm..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 123901 (2020)
Concurrent photonic measurement of angle-of-arrival and chirp rate of microwave LFM signal
Shangyuan Li, Haidong Cao, and Xiaoping Zheng
A photonic approach to concurrently measure the angle-of-arrival (AOA) and the chirp rate of a linear frequency modulated (LFM) signal is proposed and experimentally demonstrated. The measurement is achieved by estimating the differential frequency of a two-tone signal output by a dual-parallel Mach–Zehnder modulator and an additional asymmetry Mach–Zehnder interferometer. Experiments show that the AOA and the chirp rate are measured simultaneously, with an AOA measurement error of ±0.1° at an signal-to-noise ratio (SNR) of 9.6 dB. When the SNR is -10.4 dB, the AOA error is ±1.3°, and the chirp rate, measured as 210.2±1.5 Hz/ps, has a standard deviation of 0.7%. The measured chirp rate agrees well with the real LFM signal.A photonic approach to concurrently measure the angle-of-arrival (AOA) and the chirp rate of a linear frequency modulated (LFM) signal is proposed and experimentally demonstrated. The measurement is achieved by estimating the differential frequency of a two-tone signal output by a dual-parallel Mach–Zehnder modulator and an additional asymmetry Mach–Zehnder interferometer. Experiments show that the AOA and the chirp rate are measured simultaneously, with an AOA measurement error of
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 123902 (2020)
Nonlinear Optics
Neural-network-assisted femtosecond laser pulse duration measurement using two-photon absorption
Junbao Chen, Ming Wang, and Wei Xia
In this work, a neural network (NN) method is developed for pulse duration inferring for an erbium-doped fiber laser at 1550 nm. Experimentally, the interferometric autocorrelation trace is observed clearly with the use of the two-photon absorption (TPA) effect in a GaAs photodiode. The intensity autocorrelation function is curve-fitted by the NN with an appropriate performance, and the measuring accuracy is consistent with a commercial autocorrelator. Compared with the Levenberg–Marquardt curve-fitting method, the NN can retrieve the intensity autocorrelation function more stably and has a certain noise reduction ability, simplifying the signal processing for a TPA photodiode-based autocorrelator.In this work, a neural network (NN) method is developed for pulse duration inferring for an erbium-doped fiber laser at 1550 nm. Experimentally, the interferometric autocorrelation trace is observed clearly with the use of the two-photon absorption (TPA) effect in a GaAs photodiode. The intensity autocorrelation function is curve-fitted by the NN with an appropriate performance, and the measuring accuracy is consistent with a commercial autocorrelator. Compared with the Levenberg–Marquardt curve-fitting method, the NN can retrieve the intensity autocorrelation function more stably and has a certain noise reduction ability, simplifying the signal processing for a TPA photodiode-based autocorrelator..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121901 (2020)
Robust second-order correlation of twin parametric beams generated by amplified spontaneous parametric down-conversion
Kunpeng Jia, Xiaohan Wang, Xinjie Lü, Ping Xu, Zhenlin Wang, Chee Wei Wong, Gang Zhao, Yan-Xiao Gong, Zhenda Xie, and Shining Zhu
We report an observation of the second-order correlation between twin beams generated by amplified spontaneous parametric down-conversion operating above threshold with kilowatt-level peak power, from a periodically poled LiTaO3 crystal via a single-pass scheme. Photocurrent correlation was measured because of the bright photon streams, with raw visibility of 37.9% or 97.3% after electronic filtering. As expected in our theory, this correlation is robust and insensitive to parametric gain and detection loss, enabling important applications in optical communications, precision measurement, and nonlocal imaging.We report an observation of the second-order correlation between twin beams generated by amplified spontaneous parametric down-conversion operating above threshold with kilowatt-level peak power, from a periodically poled LiTaO3 crystal via a single-pass scheme. Photocurrent correlation was measured because of the bright photon streams, with raw visibility of 37.9% or 97.3% after electronic filtering. As expected in our theory, this correlation is robust and insensitive to parametric gain and detection loss, enabling important applications in optical communications, precision measurement, and nonlocal imaging..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121902 (2020)
Optical Design and Fabrication
Gabor superlens with variable focus
A. Garza-Rivera, J. E. Gómez-Correa, F. J. Renero-Carrillo, J. P. Trevino, and V. Coello
In this Letter, a Gabor superlens with variable focus is presented. This configuration uses tunable liquid lenses in the third microlens array of the Gabor superlens. By applying voltage, the radius of curvature of the micro-tunable doublet arrays changes, and the Gabor conditions are fulfilled at different focal planes. As a consequence, the magnification of the image at the focal planes changes, and a zoom effect is observed. The marginal depth plane for this system goes from 0.86 to 0.89 mm. The optical simulation, calculations, and results of the simulated optical system performance are presented.In this Letter, a Gabor superlens with variable focus is presented. This configuration uses tunable liquid lenses in the third microlens array of the Gabor superlens. By applying voltage, the radius of curvature of the micro-tunable doublet arrays changes, and the Gabor conditions are fulfilled at different focal planes. As a consequence, the magnification of the image at the focal planes changes, and a zoom effect is observed. The marginal depth plane for this system goes from 0.86 to 0.89 mm. The optical simulation, calculations, and results of the simulated optical system performance are presented..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 122201 (2020)
Optical Materials
Broadband fluorescence emission in Bi-doped silica glass prepared by laser additive manufacturing technology
Jiaming Li, Chuangkai Li, Yun Chen, Nan Zhao, Zhiyun Hou, Qingmao Zhang, and Guiyao Zhou
In this work, we proposed a feasible method to prepare the Bi/Al co-doped silica glass by using laser additive manufacturing technology. Bi was uniformly doped into the silica matrix. The hydroxyl content of the glass sample was measured to be 29.36 ppm. Using an 808 nm laser diode as the excitation source, a broadband near-infrared emission from 1000 to 1600 nm was obtained. The emission peak was centered at 1249 nm, and the corresponding FWHM was more than 400 nm. The results show that the laser additive manufacturing technology is promising to fabricate highly homogeneous Bi-doped core materials with broader emission band, which is beneficial to solving the communication capacity crunch and promotes the development of fiber communication in the upcoming fifth and sixth generation systems.In this work, we proposed a feasible method to prepare the Bi/Al co-doped silica glass by using laser additive manufacturing technology. Bi was uniformly doped into the silica matrix. The hydroxyl content of the glass sample was measured to be 29.36 ppm. Using an 808 nm laser diode as the excitation source, a broadband near-infrared emission from 1000 to 1600 nm was obtained. The emission peak was centered at 1249 nm, and the corresponding FWHM was more than 400 nm. The results show that the laser additive manufacturing technology is promising to fabricate highly homogeneous Bi-doped core materials with broader emission band, which is beneficial to solving the communication capacity crunch and promotes the development of fiber communication in the upcoming fifth and sixth generation systems..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 121601 (2020)
Physical Optics
Tunable azimuthally non-uniform orbital angular momentum carried by vector optical fields
Yue Pan, Xu-Zhen Gao, Rende Ma, Chenghou Tu, Yongnan Li, and Hui-Tian Wang
Orbital angular momentum (OAM), as a fundamental parameter of a photon, has attracted great attention in recent years. Although various properties and applications have been developed by modulating the OAM of photons, there is rare research about the non-uniform OAM. We propose and generate a new kind of continuously tunable azimuthally non-uniform OAM for the first time, to the best of our knowledge, which is carried by a hybridly polarized vector optical field with a cylindrically symmetric intensity profile and a complex polarization singularity. We also present the perfect vector optical field carrying non-uniform OAM with a fixed radius independent of topological charges, which can propagate steadily without radial separation, solving the problem of the unsteady propagation due to the broadened OAM spectrum of the non-uniform OAM. This new kind of tunable non-uniform OAM with a cylindrical symmetric intensity profile, complex polarization singularity, and propagation stability enriches the family of OAMs and can be widely used in many regions such as optical manipulation, quantum optics, and optical communications.Orbital angular momentum (OAM), as a fundamental parameter of a photon, has attracted great attention in recent years. Although various properties and applications have been developed by modulating the OAM of photons, there is rare research about the non-uniform OAM. We propose and generate a new kind of continuously tunable azimuthally non-uniform OAM for the first time, to the best of our knowledge, which is carried by a hybridly polarized vector optical field with a cylindrically symmetric intensity profile and a complex polarization singularity. We also present the perfect vector optical field carrying non-uniform OAM with a fixed radius independent of topological charges, which can propagate steadily without radial separation, solving the problem of the unsteady propagation due to the broadened OAM spectrum of the non-uniform OAM. This new kind of tunable non-uniform OAM with a cylindrical symmetric intensity profile, complex polarization singularity, and propagation stability enriches the family of OAMs and can be widely used in many regions such as optical manipulation, quantum optics, and optical communications..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 122601 (2020)
Quantum Optics and Quantum Information
Quantum fluctuation and interference effect in a single atom–cavity QED system driven by a broadband squeezed vacuum
Liangwei Wang, and Jing Shi
Squeezed vacuum, as a nonclassical field, has many interesting properties and results in many potential applications for quantum measurement and information processing. Here, we investigate a single atom–cavity quantum electrodynamics (QED) system driven by a broadband squeezed vacuum. In the presence of the atom, we show that both the mean photon number and the quantum fluctuations of photons in the cavity undergo a significant depletion due to the additional transition pathways generated by the atom–cavity interaction. By measuring these features, one can detect the existence of atoms in the cavity. We also show that two-photon excitation can be significantly suppressed by the quantum destructive interference when the squeezing parameter is very small. These results presented here are helpful in understanding the quantum nature of the broadband squeezed vacuum.Squeezed vacuum, as a nonclassical field, has many interesting properties and results in many potential applications for quantum measurement and information processing. Here, we investigate a single atom–cavity quantum electrodynamics (QED) system driven by a broadband squeezed vacuum. In the presence of the atom, we show that both the mean photon number and the quantum fluctuations of photons in the cavity undergo a significant depletion due to the additional transition pathways generated by the atom–cavity interaction. By measuring these features, one can detect the existence of atoms in the cavity. We also show that two-photon excitation can be significantly suppressed by the quantum destructive interference when the squeezing parameter is very small. These results presented here are helpful in understanding the quantum nature of the broadband squeezed vacuum..
Chinese Optics Letters
- Publication Date: Dec. 10, 2020
- Vol. 18, Issue 12, 122701 (2020)
About the Cover
Molecular-vibrational imaging by stimulated Raman scattering microscopy utilizes two-color optical pulses to provide the vibrational spectroscopic signature of biomolecules.
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