Journals >Chinese Optics Letters
Contents
2023
Volume: 21 Issue 8
13 Article(s)
Export citation format
Research Articles
Atomic and Molecular Optics
Momentum filtering scheme of cooling atomic clouds for the Chinese Space Station
Hui Li, Biao Wu, Jiachen Yu, Xiaolong Yuan, Xiaoji Zhou, Bin Wang, Weibiao Chen, Wei Xiong, and Xuzong Chen
To obtain cold atom samples with temperatures lower than 100 pK in the cold atom physics rack experiment of the Chinese Space Station, we propose to use the momentum filtering method for deep cooling of atoms. This paper introduces the experimental results of the momentum filtering method verified by our ground testing system. In the experiment, we designed a specific experimental sequence of standing-wave light pulses to control the temperature, atomic number, and size of the atomic cloud. The results show that the momentum filter can effectively and conveniently reduce the temperature of the atomic cloud and the energy of Bose–Einstein condensation, and can be flexibly combined with other cooling methods to enhance the cooling effect. This work provides a method for the atomic cooling scheme of the ultra-cold atomic system on the ground and on the space station, and shows a way of deep cooling atoms.To obtain cold atom samples with temperatures lower than 100 pK in the cold atom physics rack experiment of the Chinese Space Station, we propose to use the momentum filtering method for deep cooling of atoms. This paper introduces the experimental results of the momentum filtering method verified by our ground testing system. In the experiment, we designed a specific experimental sequence of standing-wave light pulses to control the temperature, atomic number, and size of the atomic cloud. The results show that the momentum filter can effectively and conveniently reduce the temperature of the atomic cloud and the energy of Bose–Einstein condensation, and can be flexibly combined with other cooling methods to enhance the cooling effect. This work provides a method for the atomic cooling scheme of the ultra-cold atomic system on the ground and on the space station, and shows a way of deep cooling atoms..
Chinese Optics Letters
- Publication Date: Aug. 08, 2023
- Vol. 21, Issue 8, 080201 (2023)
Diffraction, Gratings, and Holography
Suppressing defocus noise with U-net in optical scanning holography
Haiyan Ou, Yong Wu, Kun Zhu, Edmund Y. Lam, and Bing-Zhong Wang
Optical scanning holography (OSH) records both the amplitude and phase information of a 3D object by a 2D scan. To reconstruct a 3D volumetric image from an OSH hologram is difficult, as it suffers from the defocus noise from the other sections. The use of a random phase pupil can convert defocus noise into speckle-like noise, which may require further processing in sectional image reconstruction. In this paper, we propose a U-shaped neural network to reduce this speckle haze. Simulation results show that the proposed method works effectively and efficiently both in simple and complex graphics.Optical scanning holography (OSH) records both the amplitude and phase information of a 3D object by a 2D scan. To reconstruct a 3D volumetric image from an OSH hologram is difficult, as it suffers from the defocus noise from the other sections. The use of a random phase pupil can convert defocus noise into speckle-like noise, which may require further processing in sectional image reconstruction. In this paper, we propose a U-shaped neural network to reduce this speckle haze. Simulation results show that the proposed method works effectively and efficiently both in simple and complex graphics..
Chinese Optics Letters
- Publication Date: Aug. 07, 2023
- Vol. 21, Issue 8, 080501 (2023)
Imaging Systems and Image Processing
Underwater ghost imaging with pseudo-Bessel-ring modulation pattern | Editors' Pick
Zhe Sun, Tong Tian, Sukyoon Oh, Jiang Wang, Guanghua Cheng, and Xuelong Li
In this study, we propose an underwater ghost-imaging scheme using a modulation pattern combining offset-position pseudo-Bessel-ring (OPBR) and random binary (RB) speckle pattern illumination. We design the experiments based on modulation rules to order the OPBR speckle patterns. We retrieve ghost images by OPBR beam with different modulation speckle sizes. The obtained ghost images have a better contrast-to-noise rate compared to RB beam ghost imaging under the same conditions. We verify the results both in the experiment and simulation. In addition, we also check the image quality at different turbidities. Furthermore, we demonstrate that the OPBR speckle pattern also provides better image quality in other objects. The proposed method promises wide applications in highly scattering media, atmosphere, turbid water, etc.In this study, we propose an underwater ghost-imaging scheme using a modulation pattern combining offset-position pseudo-Bessel-ring (OPBR) and random binary (RB) speckle pattern illumination. We design the experiments based on modulation rules to order the OPBR speckle patterns. We retrieve ghost images by OPBR beam with different modulation speckle sizes. The obtained ghost images have a better contrast-to-noise rate compared to RB beam ghost imaging under the same conditions. We verify the results both in the experiment and simulation. In addition, we also check the image quality at different turbidities. Furthermore, we demonstrate that the OPBR speckle pattern also provides better image quality in other objects. The proposed method promises wide applications in highly scattering media, atmosphere, turbid water, etc..
Chinese Optics Letters
- Publication Date: Aug. 02, 2023
- Vol. 21, Issue 8, 081101 (2023)
Integrated Optics
Cryogenic thermo-optic thin-film lithium niobate modulator with an NbN superconducting heater
Hailong Han, Xingyu Zhang, You Xiao, Pusheng Yuan, Huiqin Yu, Shuna Wang, Heng Li, Weikeng Xie, Mingzhi Lu, Lingyun Li, Xiaoping Liu, Hao Li, and Lixing You
We propose and demonstrate a cryogenic thermo-optic (TO) modulator in x-cut thin-film lithium niobate (TFLN) with an NbN superconducting heater. Compared to a conventional metal heating electrode, a fast and energy-efficient modulation is obtained by placing an NbN superconducting heating electrode above the TFLN waveguide. The transition of the NbN superconducting electrode between superconducting and normal states turns the heating and cooling processes from continuous to discontinuous change. Thus, the energy consumption during the modulation process is reduced proportionally. The rise/fall time of the proposed device is 22 µs/15 µs, which has been the fastest response time reported in TFLN thermo-optic modulators so far. The presented TO modulator can easily be used at cryogenic temperatures and has great potential for applications in cryogenic optoelectronics.We propose and demonstrate a cryogenic thermo-optic (TO) modulator in x-cut thin-film lithium niobate (TFLN) with an NbN superconducting heater. Compared to a conventional metal heating electrode, a fast and energy-efficient modulation is obtained by placing an NbN superconducting heating electrode above the TFLN waveguide. The transition of the NbN superconducting electrode between superconducting and normal states turns the heating and cooling processes from continuous to discontinuous change. Thus, the energy consumption during the modulation process is reduced proportionally. The rise/fall time of the proposed device is 22 µs/15 µs, which has been the fastest response time reported in TFLN thermo-optic modulators so far. The presented TO modulator can easily be used at cryogenic temperatures and has great potential for applications in cryogenic optoelectronics..
Chinese Optics Letters
- Publication Date: Aug. 08, 2023
- Vol. 21, Issue 8, 081301 (2023)
Lasers, Optical Amplifiers, and Laser Optics
Immersed liquid cooling Nd:YAG slab laser oscillator
Zhibin Ye, Xiaolong Zhou, Shu Jiang, Meng Huang, Fei Wu, and Dongge Lei
An immersed liquid cooling slab laser is demonstrated with deionized water as the coolant and a Nd:YAG slab as the gain medium. Using waveguides, a highly uniform pump beam distribution is achieved, and the flow velocity distribution is also optimized in the channels of the gain module (GM). At various flow velocities, the convective heat transfer coefficient (CHTC) is obtained. Experimentally, a maximum output power of 434 W is obtained with an optical–optical efficiency of 27.1% and a slope efficiency of 36.6%. To the best of our knowledge, it is the highest output power of an immersed liquid cooling laser oscillator with a single Nd:YAG slab.An immersed liquid cooling slab laser is demonstrated with deionized water as the coolant and a Nd:YAG slab as the gain medium. Using waveguides, a highly uniform pump beam distribution is achieved, and the flow velocity distribution is also optimized in the channels of the gain module (GM). At various flow velocities, the convective heat transfer coefficient (CHTC) is obtained. Experimentally, a maximum output power of 434 W is obtained with an optical–optical efficiency of 27.1% and a slope efficiency of 36.6%. To the best of our knowledge, it is the highest output power of an immersed liquid cooling laser oscillator with a single Nd:YAG slab..
Chinese Optics Letters
- Publication Date: Aug. 02, 2023
- Vol. 21, Issue 8, 081401 (2023)
Coherent combining of a fiber laser array via cascaded internal phase control technique
Jinhu Long, Jiayi Zhang, Hongxiang Chang, Qi Chang, Yu Deng, Zixin Yang, Jian Wu, Rongtao Su, Yanxing Ma, Pengfei Ma, and Pu Zhou
We experimentally demonstrated a cascaded internal phase control technique. A laser array with 12 channels was divided into three sub-arrays and a stage array, and phases of the sub-arrays and the stage array were locked by four phase controllers based on the stochastic parallel gradient descent (SPGD) algorithm, respectively. In this way, the phases of the whole array were locked, and the visibility of the interference pattern of the whole emitted laser array in the far field was ∼93%. In addition, the technique has the advantage of element expanding and can be further used in the high-power coherent beam combination (CBC) system due to its compact spatial structure.We experimentally demonstrated a cascaded internal phase control technique. A laser array with 12 channels was divided into three sub-arrays and a stage array, and phases of the sub-arrays and the stage array were locked by four phase controllers based on the stochastic parallel gradient descent (SPGD) algorithm, respectively. In this way, the phases of the whole array were locked, and the visibility of the interference pattern of the whole emitted laser array in the far field was
Chinese Optics Letters
- Publication Date: Aug. 07, 2023
- Vol. 21, Issue 8, 081402 (2023)
Nonlinear Optics
Nonlinear harmonic generation of terahertz waves in a topological valley polaritonic microcavity
Yao Lu, Hao Xiong, Yibo Huang, Qiang Wu, Jiwei Qi, Chongpei Pan, and Jingjun Xu
Compact terahertz (THz) devices, especially for nonlinear THz components, have received more and more attention due to their potential applications in THz nonlinearity-based sensing, communications, and computing devices. However, effective means to enhance, control, and confine the nonlinear harmonics of THz waves remain a great challenge for micro-scale THz nonlinear devices. In this work, we have established a technique for nonlinear harmonic generation of THz waves based on phonon polariton-enhanced giant THz nonlinearity in a 2D-topologically protected valley photonic microcavity. Effective THz harmonic generation has been observed in both noncentrosymmetric and centrosymmetric nonlinear materials. These results can provide a valuable reference for the generation and control of THz high-harmonics, thus developing new nonlinear devices in the THz regime.Compact terahertz (THz) devices, especially for nonlinear THz components, have received more and more attention due to their potential applications in THz nonlinearity-based sensing, communications, and computing devices. However, effective means to enhance, control, and confine the nonlinear harmonics of THz waves remain a great challenge for micro-scale THz nonlinear devices. In this work, we have established a technique for nonlinear harmonic generation of THz waves based on phonon polariton-enhanced giant THz nonlinearity in a 2D-topologically protected valley photonic microcavity. Effective THz harmonic generation has been observed in both noncentrosymmetric and centrosymmetric nonlinear materials. These results can provide a valuable reference for the generation and control of THz high-harmonics, thus developing new nonlinear devices in the THz regime..
Chinese Optics Letters
- Publication Date: Aug. 07, 2023
- Vol. 21, Issue 8, 081901 (2023)
Thickness dependency of nonlinear optical properties in ITO/Sn composite films
Boyang Nan, Ruijin Hong, Chunxian Tao, Qi Wang, Hui Lin, Zhaoxia Han, and Dawei Zhang
In this study, a batch of indium tin oxide (ITO)/Sn composites with different ratios was obtained based on the principle of thermal evaporation by an electron beam. The crystalline structure, surface shape, and optical characterization of the films were researched using an X-ray diffractometer, an atomic force microscope, a UV-Vis-NIR dual-beam spectrophotometer, and an open-hole Z-scan system. By varying the relative thickness ratio of the ITO/Sn bilayer film, tunable nonlinear optical properties were achieved. The nonlinear saturation absorption coefficient β maximum of the ITO/Sn composites is -10.5×10-7 cm/W, approximately 21 and 1.72 times more enhanced compared to monolayer ITO and Sn, respectively. Moreover, the improvement of the sample nonlinear performance was verified using finite-difference in temporal domain simulations.In this study, a batch of indium tin oxide (ITO)/Sn composites with different ratios was obtained based on the principle of thermal evaporation by an electron beam. The crystalline structure, surface shape, and optical characterization of the films were researched using an X-ray diffractometer, an atomic force microscope, a UV-Vis-NIR dual-beam spectrophotometer, and an open-hole Z-scan system. By varying the relative thickness ratio of the ITO/Sn bilayer film, tunable nonlinear optical properties were achieved. The nonlinear saturation absorption coefficient
Chinese Optics Letters
- Publication Date: Aug. 08, 2023
- Vol. 21, Issue 8, 081902 (2023)
Quantum Optics and Quantum Information
Surpassing the standard quantum limit of optical imaging via deep learning
Miao Cai, Zhi-Xiang Li, Hao-Dong Wu, Ya-Ping Ruan, Lei Tang, Jiang-Shan Tang, Ming-Yuan Chen, Han Zhang, Ke-Yu Xia, Min Xiao, and Yan-Qing Lu
The sensitivity of optical measurement is ultimately constrained by the shot noise to the standard quantum limit. It has become a common concept that beating this limit requires quantum resources. A deep-learning neural network free of quantum principle has the capability of removing classical noise from images, but it is unclear in reducing quantum noise. In a coincidence-imaging experiment, we show that quantum-resource-free deep learning can be exploited to surpass the standard quantum limit via the photon-number-dependent nonlinear feedback during training. Using an effective classical light with photon flux of about 9×104 photons per second, our deep-learning-based scheme achieves a 14 dB improvement in signal-to-noise ratio with respect to the standard quantum limit.The sensitivity of optical measurement is ultimately constrained by the shot noise to the standard quantum limit. It has become a common concept that beating this limit requires quantum resources. A deep-learning neural network free of quantum principle has the capability of removing classical noise from images, but it is unclear in reducing quantum noise. In a coincidence-imaging experiment, we show that quantum-resource-free deep learning can be exploited to surpass the standard quantum limit via the photon-number-dependent nonlinear feedback during training. Using an effective classical light with photon flux of about
Chinese Optics Letters
- Publication Date: Aug. 08, 2023
- Vol. 21, Issue 8, 082701 (2023)
Special Issue on Spatiotemporal Optical Fields and Time-Varying Optical Materials
Temporal manipulation of spatiotemporal optical vortices with an Airy pulse [Invited]
Yimin Zang, Fanli Wei, Hee Sung Kim, and Andy Chong
We demonstrate the temporal manipulation of spatiotemporal optical vortices (STOVs) by utilizing Airy pulses. By combining a STOV with an Airy temporal profile, the STOV exhibits nondispersive, self-accelerating, and self-healing features inherited from the Airy pulse propagation. Such features will enhance the control of STOVs in time.We demonstrate the temporal manipulation of spatiotemporal optical vortices (STOVs) by utilizing Airy pulses. By combining a STOV with an Airy temporal profile, the STOV exhibits nondispersive, self-accelerating, and self-healing features inherited from the Airy pulse propagation. Such features will enhance the control of STOVs in time..
Chinese Optics Letters
- Publication Date: Aug. 08, 2023
- Vol. 21, Issue 8, 080002 (2023)
Spatiotemporal optical vortex wavepackets with phase singularities embedded in multiple domains [Invited] | On the Cover
Liangliang Gu, Qian Cao, and Qiwen Zhan
Spatiotemporal optical vortex (STOV) wavepacket carrying transverse photonic orbital angular momentum (OAM) has been extensively studied in the past few years. In this Letter, we propose and study a novel STOV wavepacket with multiple phase singularities embedded in different space–time domains using analytical and numerical approaches. By tuning different parameters used for designing the wavepacket, it is possible to engineer both the magnitude and orientation of the photonic OAM in space–time. The vectorially controllable OAM will pave new avenues and facilitate applications such as novel optical communication, studying complicated quantum systems, and spin-and-OAM interactions.Spatiotemporal optical vortex (STOV) wavepacket carrying transverse photonic orbital angular momentum (OAM) has been extensively studied in the past few years. In this Letter, we propose and study a novel STOV wavepacket with multiple phase singularities embedded in different space–time domains using analytical and numerical approaches. By tuning different parameters used for designing the wavepacket, it is possible to engineer both the magnitude and orientation of the photonic OAM in space–time. The vectorially controllable OAM will pave new avenues and facilitate applications such as novel optical communication, studying complicated quantum systems, and spin-and-OAM interactions..
Chinese Optics Letters
- Publication Date: Aug. 07, 2023
- Vol. 21, Issue 8, 080003 (2023)
Spatiotemporal optical vortices generation in the green and ultraviolet via frequency upconversion [Invited] | Editors' Pick
Xuechen Gao, Yuwei Zhao, Jue Wang, Yang Lu, Jiaxuan Zhang, Jintao Fan, and Minglie Hu
As a newly discovered type of structured light, a spatiotemporal optical vortex (STOV), which is remarkable for its space–time spiral phase and transverse orbital angular momentum (OAM), has garnered substantial interest. Most previous studies have focused on the generation, characterization, and propagation of STOVs, but their nonlinear frequency conversion remains largely unexplored. Here, we experimentally demonstrate the generation of green and ultraviolet (UV) STOVs by frequency upconversion of a STOV carried near-infrared (NIR) pulse emitted by a high repetition rate Yb-doped fiber laser amplifier system. First, we verify that the topological charge of spatiotemporal OAM (ST-OAM) is doubled along with the optical frequency in the second-harmonic generation (SHG) process, which is visualized by the diffraction patterns of the STOVs in the fundamental and second-harmonic field. Second, the space–time characteristic of NIR STOV is successfully mapped to UV STOV by sum-frequency mixing STOV at 1037 nm and Gaussian beams in the green band. Furthermore, we observe the topological charges of the ST-OAM could be degraded owing to strong space–time coupling and complex spatiotemporal astigmatism of such beams. Our results not only deepen our understanding of nonlinear manipulation of ST-OAM spectra and the generation of STOVs at a new shorter wavelength, but also may promote new applications in both classical and quantum optics.As a newly discovered type of structured light, a spatiotemporal optical vortex (STOV), which is remarkable for its space–time spiral phase and transverse orbital angular momentum (OAM), has garnered substantial interest. Most previous studies have focused on the generation, characterization, and propagation of STOVs, but their nonlinear frequency conversion remains largely unexplored. Here, we experimentally demonstrate the generation of green and ultraviolet (UV) STOVs by frequency upconversion of a STOV carried near-infrared (NIR) pulse emitted by a high repetition rate Yb-doped fiber laser amplifier system. First, we verify that the topological charge of spatiotemporal OAM (ST-OAM) is doubled along with the optical frequency in the second-harmonic generation (SHG) process, which is visualized by the diffraction patterns of the STOVs in the fundamental and second-harmonic field. Second, the space–time characteristic of NIR STOV is successfully mapped to UV STOV by sum-frequency mixing STOV at 1037 nm and Gaussian beams in the green band. Furthermore, we observe the topological charges of the ST-OAM could be degraded owing to strong space–time coupling and complex spatiotemporal astigmatism of such beams. Our results not only deepen our understanding of nonlinear manipulation of ST-OAM spectra and the generation of STOVs at a new shorter wavelength, but also may promote new applications in both classical and quantum optics..
Chinese Optics Letters
- Publication Date: Aug. 07, 2023
- Vol. 21, Issue 8, 080004 (2023)
Simultaneous wireless information and power transfer transmitting architecture based on asynchronous space-time-coding digital metasurface [Invited]
Zhen Jie Qi, Jun Yan Dai, Si Ran Wang, Qun Yan Zhou, Wankai Tang, Kaicen Wang, Peng Zhang, Shuo Liu, Long Li, Qiang Cheng, and Tie Jun Cui
Simultaneous wireless information and power transfer (SWIPT) architecture is commonly applied in wireless sensors or Internet of Things (IoT) devices, providing both wireless power sources and communication channels. However, the traditional SWIPT transmitter usually suffers from cross-talk distortion caused by the high peak-to-average power ratio of the input signal and the reduction of power amplifier efficiency. This paper proposes a SWIPT transmitting architecture based on an asynchronous space-time-coding digital metasurface (ASTCM). High-efficiency simultaneous transfer of information and power is achieved via energy distribution and information processing of the wireless monophonic signal reflected from the metasurface. We demonstrate the feasibility of the proposed method through theoretical derivations and experimental verification, which is therefore believed to have great potential in wireless communications and the IoT devices.Simultaneous wireless information and power transfer (SWIPT) architecture is commonly applied in wireless sensors or Internet of Things (IoT) devices, providing both wireless power sources and communication channels. However, the traditional SWIPT transmitter usually suffers from cross-talk distortion caused by the high peak-to-average power ratio of the input signal and the reduction of power amplifier efficiency. This paper proposes a SWIPT transmitting architecture based on an asynchronous space-time-coding digital metasurface (ASTCM). High-efficiency simultaneous transfer of information and power is achieved via energy distribution and information processing of the wireless monophonic signal reflected from the metasurface. We demonstrate the feasibility of the proposed method through theoretical derivations and experimental verification, which is therefore believed to have great potential in wireless communications and the IoT devices..
Chinese Optics Letters
- Publication Date: Aug. 07, 2023
- Vol. 21, Issue 8, 080005 (2023)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20