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Physical Optics|48 Article(s)
Constructing arbitrary self-similar Bessel-like beams via transverse-longitudinal mapping|On the Cover
Yanke Li, Yu Zou, Zhaojin Guo, Sheng Liu, Peng Li, Bingyan Wei, Dandan Wen, and Jianlin Zhao
Based on the transverse-longitudinal mapping of Bessel beams, we propose a simple method to construct a self-similar Bessel-like beam whose transverse profile maintains a stretched form during propagation. Specifically, the propagating-variant width of this beam can be flexibly predesigned. We experimentally demonstrate three types of self-similar Bessel-like beams whose width variations are linear, piecewise, and period functions of propagation distance, respectively. The experimental results match well with the theoretical predictions. We also demonstrate that our approach enables the generation of self-similar higher-order vortex Bessel-like beams. Based on the transverse-longitudinal mapping of Bessel beams, we propose a simple method to construct a self-similar Bessel-like beam whose transverse profile maintains a stretched form during propagation. Specifically, the propagating-variant width of this beam can be flexibly predesigned. We experimentally demonstrate three types of self-similar Bessel-like beams whose width variations are linear, piecewise, and period functions of propagation distance, respectively. The experimental results match well with the theoretical predictions. We also demonstrate that our approach enables the generation of self-similar higher-order vortex Bessel-like beams.
Chinese Optics Letters
- Publication Date: Feb. 27, 2024
- Vol. 22, Issue 2, 022601 (2024)
Constructing ultra-long focal fields via tightly focused Bessel beams
Zhaojin Guo, Mingshuai Huang, Sheng Liu, Peng Li, Bingyan Wei, and Jianlin Zhao
We numerically demonstrate that the tight focusing of Bessel beams can generate focal fields with an ultra-long depth of focus (DOF). The ultra-long focal field can be controlled by appropriately regulating the order of the Bessel function and the polarization. An optical needle and an optical dark channel with nearly 100λ DOF are generated. The optical needle has a DOF of ∼104.9λ and a super-diffraction-limited focal spot with the size of 0.19λ2. The dark channel has a full-width at half-maximum of ∼0.346λ and a DOF of ∼103.8λ. Furthermore, the oscillating focal field with an ultra-long DOF can be also generated by merely changing the order of the input Bessel beam. Our results are expected to contribute to potential applications in optical tweezers, atom guidance and capture, and laser processing. We numerically demonstrate that the tight focusing of Bessel beams can generate focal fields with an ultra-long depth of focus (DOF). The ultra-long focal field can be controlled by appropriately regulating the order of the Bessel function and the polarization. An optical needle and an optical dark channel with nearly 100λ DOF are generated. The optical needle has a DOF of ∼104.9λ and a super-diffraction-limited focal spot with the size of 0.19λ2. The dark channel has a full-width at half-maximum of ∼0.346λ and a DOF of ∼103.8λ. Furthermore, the oscillating focal field with an ultra-long DOF can be also generated by merely changing the order of the input Bessel beam. Our results are expected to contribute to potential applications in optical tweezers, atom guidance and capture, and laser processing.
Chinese Optics Letters
- Publication Date: Jul. 10, 2023
- Vol. 21, Issue 7, 072601 (2023)
Quantum-limited resolution of partially coherent sources
Ben Wang, Liang Xu, Hongkuan Xia, Aonan Zhang, Kaimin Zheng, and Lijian Zhang
Discriminating two spatially separated sources is one of the most fundamental problems in imaging. Recent research based on quantum parameter estimation theory shows that the resolution limit of two incoherent point sources given by Rayleigh can be broken. However, in realistic optical systems, there often exists coherence in the imaging light field, and there have been efforts to analyze the optical resolution in the presence of partial coherence. Nevertheless, how the degree of coherence between two point sources affects the resolution has not been fully understood. Here, we analyze the quantum-limited resolution of two partially coherent point sources by explicitly relating the state after evolution through the optical systems to the coherence of the sources. In particular, we consider the situation in which coherence varies with the separation. We propose a feasible experiment scheme to realize the nearly optimal measurement, which adaptively chooses the binary spatial-mode demultiplexing measurement and direct imaging. Our results will have wide applications in imaging involving coherence of light. Discriminating two spatially separated sources is one of the most fundamental problems in imaging. Recent research based on quantum parameter estimation theory shows that the resolution limit of two incoherent point sources given by Rayleigh can be broken. However, in realistic optical systems, there often exists coherence in the imaging light field, and there have been efforts to analyze the optical resolution in the presence of partial coherence. Nevertheless, how the degree of coherence between two point sources affects the resolution has not been fully understood. Here, we analyze the quantum-limited resolution of two partially coherent point sources by explicitly relating the state after evolution through the optical systems to the coherence of the sources. In particular, we consider the situation in which coherence varies with the separation. We propose a feasible experiment scheme to realize the nearly optimal measurement, which adaptively chooses the binary spatial-mode demultiplexing measurement and direct imaging. Our results will have wide applications in imaging involving coherence of light.
Chinese Optics Letters
- Publication Date: Mar. 10, 2023
- Vol. 21, Issue 4, 042601 (2023)
Full description of dipole orientation in organic light-emitting diodes
Lingjie Fan, Maoxiong Zhao, Jiao Chu, Tangyao Shen, Minjia Zheng, Fang Guan, Haiwei Yin, Lei Shi, and Jian Zi
Considerable progress has been made in organic light-emitting diodes (OLEDs) to achieve high external quantum efficiency, among which dipole orientation has a remarkable effect. In most cases, the radiation of the dipoles in OLEDs is theoretically predicted with only one orientation parameter to match with corresponding experiments. Here, we develop a new theory with three orientation parameters to fully describe the relationship between dipole orientation and power density. Furthermore, we design an optimal test structure for measuring all three orientation parameters. All three orientation parameters could be retrieved from non-polarized spectra. Our theory provides a universal plot of dipole orientations in OLEDs, paving the way for designing more complicated OLED devices. Considerable progress has been made in organic light-emitting diodes (OLEDs) to achieve high external quantum efficiency, among which dipole orientation has a remarkable effect. In most cases, the radiation of the dipoles in OLEDs is theoretically predicted with only one orientation parameter to match with corresponding experiments. Here, we develop a new theory with three orientation parameters to fully describe the relationship between dipole orientation and power density. Furthermore, we design an optimal test structure for measuring all three orientation parameters. All three orientation parameters could be retrieved from non-polarized spectra. Our theory provides a universal plot of dipole orientations in OLEDs, paving the way for designing more complicated OLED devices.
Chinese Optics Letters
- Publication Date: Sep. 20, 2022
- Vol. 21, Issue 2, 022601 (2023)
Optical spiral vortex from azimuthally increasing/decreasing exponential phase gradients
Peihua Jie, Zhenwei Xie, and Xiaocong Yuan
A new type of power-exponent-phase vortex-like beams with both quadratic and cubic azimuthal phase gradients is investigated in this work. The intensity and orbital angular momentum (OAM) density distributions are noticeably different when the phase gradient increases or decreases along the azimuth angle, while the orthogonality and total OAM remain constant. The characteristics of the optical field undergo a significant change when the phase shifts from linear to nonlinear, with the variation of the power index having little impact on the beam characteristics under nonlinear phase conditions. These characteristics provide new ideas for applications such as particle manipulation, optical communications, and OAM encryption. A new type of power-exponent-phase vortex-like beams with both quadratic and cubic azimuthal phase gradients is investigated in this work. The intensity and orbital angular momentum (OAM) density distributions are noticeably different when the phase gradient increases or decreases along the azimuth angle, while the orthogonality and total OAM remain constant. The characteristics of the optical field undergo a significant change when the phase shifts from linear to nonlinear, with the variation of the power index having little impact on the beam characteristics under nonlinear phase conditions. These characteristics provide new ideas for applications such as particle manipulation, optical communications, and OAM encryption.
Chinese Optics Letters
- Publication Date: Nov. 05, 2023
- Vol. 21, Issue 11, 112601 (2023)
Generation of shaping nondiffracting structured caustic beams on the basis of stationary phase principle
Rijian Chen, Yile Shi, Ning Gong, Yefeng Liu, and Zhijun Ren
On the basis of the stationary phase principle, we construct a family of shaping nondiffracting structured caustic beams with the desired morphology. First, the analytical formula of a nondiffracting astroid caustic is derived theoretically using the stationary phase method. Then, several types of typical desired caustics with different shapes are numerically simulated using the obtained formulas. Hence, the key optical structure and propagation characteristics of nondiffracting caustic beams are investigated. Finally, a designed phase plate and an axicon are used to generate the target light field. The experimental results confirm the theoretical prediction. Compared with the classical method, the introduced method for generating nondiffracting caustic beams is high in light-energy utilization; hence, it is expected to be applied conveniently to scientific experiments. On the basis of the stationary phase principle, we construct a family of shaping nondiffracting structured caustic beams with the desired morphology. First, the analytical formula of a nondiffracting astroid caustic is derived theoretically using the stationary phase method. Then, several types of typical desired caustics with different shapes are numerically simulated using the obtained formulas. Hence, the key optical structure and propagation characteristics of nondiffracting caustic beams are investigated. Finally, a designed phase plate and an axicon are used to generate the target light field. The experimental results confirm the theoretical prediction. Compared with the classical method, the introduced method for generating nondiffracting caustic beams is high in light-energy utilization; hence, it is expected to be applied conveniently to scientific experiments.
Chinese Optics Letters
- Publication Date: Aug. 31, 2023
- Vol. 21, Issue 10, 102601 (2023)
Underwater Bessel-like beams with enlarged depth of focus based on fiber microaxicon|Editors' Pick
Xiaoying He, Mengyuan Li, and Lan Rao
Underwater optical wireless communication, which is useful for oceanography, environmental monitoring, and underwater surveillance, suffers the limit of the absorption attenuation and Mie–Rayleigh scattering of the lights. Here, Bessel-like beams generated by a fiber microaxicon is utilized for underwater wireless propagation. Underwater, the cone angle for generating Bessel-like beams starts from 46°, which is smaller than that in air for Bessel-like beams. When the cone angle of the fiber microaxicons is about 140°, the depth of focus underwater, which is four times as long as the depth of focus in air, has enlarged about 28 µm, 36.12 µm, and 50.7 µm for 470 nm, 520 nm, and 632 nm visible lights. The transmission distance of the Bessel beams for visible lights has been simulated by using Henyey–Greenstein–Rayleigh phase function methods and spectral absorption by bio-optical model due to Monte Carlo methods. The results show that the propagation distance could reach 4000 m, which overcome the limit of the Mie–Rayleigh scattering and absorption attenuation underwater. Underwater optical wireless communication, which is useful for oceanography, environmental monitoring, and underwater surveillance, suffers the limit of the absorption attenuation and Mie–Rayleigh scattering of the lights. Here, Bessel-like beams generated by a fiber microaxicon is utilized for underwater wireless propagation. Underwater, the cone angle for generating Bessel-like beams starts from 46°, which is smaller than that in air for Bessel-like beams. When the cone angle of the fiber microaxicons is about 140°, the depth of focus underwater, which is four times as long as the depth of focus in air, has enlarged about 28 µm, 36.12 µm, and 50.7 µm for 470 nm, 520 nm, and 632 nm visible lights. The transmission distance of the Bessel beams for visible lights has been simulated by using Henyey–Greenstein–Rayleigh phase function methods and spectral absorption by bio-optical model due to Monte Carlo methods. The results show that the propagation distance could reach 4000 m, which overcome the limit of the Mie–Rayleigh scattering and absorption attenuation underwater.
Chinese Optics Letters
- Publication Date: May. 07, 2022
- Vol. 20, Issue 7, 072601 (2022)
Asymmetric rotating array beams with free movement and revolution
Jia Xu, Zhenglin Liu, Keming Pan, and Daomu Zhao
We introduce a new class of partially coherent asymmetric array beams. When the beam propagates, the spectral density of each lobe and the corresponding degree of coherence have rotating behavior. Especially, not only can array-like lattices revolve arbitrarily, but also they can move freely by controlling transverse plane shifts. Furthermore, we have generated this kind of beam experimentally, and the experimental phenomena are consistent with the numerical simulation results. Such a rotating beam with free movement and revolution may broaden the way for optical applications. More importantly, it inspires further studies in the field of asymmetric coherence gratings and lattices. We introduce a new class of partially coherent asymmetric array beams. When the beam propagates, the spectral density of each lobe and the corresponding degree of coherence have rotating behavior. Especially, not only can array-like lattices revolve arbitrarily, but also they can move freely by controlling transverse plane shifts. Furthermore, we have generated this kind of beam experimentally, and the experimental phenomena are consistent with the numerical simulation results. Such a rotating beam with free movement and revolution may broaden the way for optical applications. More importantly, it inspires further studies in the field of asymmetric coherence gratings and lattices.
Chinese Optics Letters
- Publication Date: Jan. 04, 2022
- Vol. 20, Issue 2, 022602 (2022)
Depolarization index from Mueller matrix descatters imaging in turbid water
Fei Liu, Shichao Zhang, Pingli Han, Fangyi Chen, Lin Zhao, Yingying Fan, and Xiaopeng Shao
Polarization underwater imaging is of great potential to target detection in turbid water. Typical methods are challenged by the requirement on degrees of polarization (DoPs) of both target light and backscattering. A polarization descattering imaging method was developed using the Mueller matrix, which in turn derived a depolarization (Dep) index from the Mueller matrix to characterize scattering media by estimating the transmittance map by combining a developed optimal function. By quantifying light attenuation with the transmittance map, a clear vision of targets can be recovered. Only using the information of scattering media, the underwater vision under diverse water turbidity was enhanced by the results of experimental data. Polarization underwater imaging is of great potential to target detection in turbid water. Typical methods are challenged by the requirement on degrees of polarization (DoPs) of both target light and backscattering. A polarization descattering imaging method was developed using the Mueller matrix, which in turn derived a depolarization (Dep) index from the Mueller matrix to characterize scattering media by estimating the transmittance map by combining a developed optimal function. By quantifying light attenuation with the transmittance map, a clear vision of targets can be recovered. Only using the information of scattering media, the underwater vision under diverse water turbidity was enhanced by the results of experimental data.
Chinese Optics Letters
- Publication Date: Oct. 08, 2021
- Vol. 20, Issue 2, 022601 (2022)
Symmetry detection of rotating patterns based on rotational Doppler effect of light
Fang Han, Weijie Wang, Tong Liu, Yuan Ren, Zhengliang Liu, and Song Qiu
We propose a method for detecting the symmetry of rotating patterns based on the rotational Doppler effect (RDE) of light. The basic mechanisms of the RDE are introduced, and the spiral harmonic distribution of rotating patterns is analyzed. By irradiating the rotating pattern using a superimposed optical vortex and analyzing the amplitude of the RDE signal, the spiral harmonic distribution of the pattern can be measured, and then its symmetry can be detected. We demonstrate this method experimentally by using patterns with different symmetries and shapes. As the method does not need to receive the scattered light completely and accurately, it promises potential application in detecting symmetrical rotating objects at a long distance. We propose a method for detecting the symmetry of rotating patterns based on the rotational Doppler effect (RDE) of light. The basic mechanisms of the RDE are introduced, and the spiral harmonic distribution of rotating patterns is analyzed. By irradiating the rotating pattern using a superimposed optical vortex and analyzing the amplitude of the RDE signal, the spiral harmonic distribution of the pattern can be measured, and then its symmetry can be detected. We demonstrate this method experimentally by using patterns with different symmetries and shapes. As the method does not need to receive the scattered light completely and accurately, it promises potential application in detecting symmetrical rotating objects at a long distance.
Chinese Optics Letters
- Publication Date: Aug. 09, 2022
- Vol. 20, Issue 12, 122601 (2022)
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