Journals > > Topics > Physical Optics
Physical Optics|274 Article(s)
Propagation Characteristics of Lommel-Gaussian Beams in a Gradient-Index Medium
Yanli Su, Yuanbo Wang, Lincong Ji, Cun Zhang, and Qichang Jiang
The intensity envelopes and propagation characteristics of Lommel-Gaussian beams are investigated numerically based on gradient-index medium. The intensity expression of Lommel-Gaussian beams is provided. The zero-free region of Lommel-Gaussian beams decreases with decreasing spot of Gaussian beams, that is, the truncation effect of beams is more obvious. The spatial scale decreases with increasing half-cone angles and the hollow region of beam center increases with increasing topological charges. The spatial distribution and symmetry can be modulated by changing the asymmetric parameters. The intensity distribution of beams gradually changes from circular symmetry to axial-symmetry double-crescent pattern with increasing amplitude of asymmetric parameters and the symmetric axis of double-crescent pattern is rotated clockwise with increasing argument of asymmetric parameters. When the Lommel-Gaussian beams are propagating in a gradient-index medium, within a transmission cycle, the relative intensity distribution of beams has no change, only the beam scale has a periodic focus change. But in free space, the beam quickly evolves into two light spots. All results are helpful to study the application of Lommel-Gaussian beams. The intensity envelopes and propagation characteristics of Lommel-Gaussian beams are investigated numerically based on gradient-index medium. The intensity expression of Lommel-Gaussian beams is provided. The zero-free region of Lommel-Gaussian beams decreases with decreasing spot of Gaussian beams, that is, the truncation effect of beams is more obvious. The spatial scale decreases with increasing half-cone angles and the hollow region of beam center increases with increasing topological charges. The spatial distribution and symmetry can be modulated by changing the asymmetric parameters. The intensity distribution of beams gradually changes from circular symmetry to axial-symmetry double-crescent pattern with increasing amplitude of asymmetric parameters and the symmetric axis of double-crescent pattern is rotated clockwise with increasing argument of asymmetric parameters. When the Lommel-Gaussian beams are propagating in a gradient-index medium, within a transmission cycle, the relative intensity distribution of beams has no change, only the beam scale has a periodic focus change. But in free space, the beam quickly evolves into two light spots. All results are helpful to study the application of Lommel-Gaussian beams.
Laser & Optoelectronics Progress
- Publication Date: May. 10, 2024
- Vol. 61, Issue 9, 0926001 (2024)
Numerical Simulation of Eccentric Spatiotemporal Dual-and-Trible Optical Vortices
Dong Ye, Huaqing Song, Baichuan Lin, Junyao Li, Zongchen Li, and Yi Zhang
The spatiotemporal optical vortex has attracted the attention of researchers due to its unique property of carrying transverse orbital angular momentum. Compared with ordinary vortex beams, it can provide additional degrees of freedom and marks a higher level of modulation of light fields. Based on the spatiotemporal-spatial optical vortex with spiral phases in both spatiotemporal and spatial domains, the spatiotemporal-spatiotemporal optical vortex and spatiotemporal-spatiotemporal-spatial optical vortex with spiral phases on two different spatiotemporal planes are numerically simulated. According to the concentric situation between different vortices in the usual spatiotemporal optical vortex, by introducing parameters to modulate the position of the center of the spatiotemporal domain vortex, we have achieved the goal of eccentricity between different vortices and numerically simulated eccentric double vortex and eccentric triple vortex. This research enriches the mode of spatiotemporal optical vortices and provides a theoretical basis for their subsequent research. The spatiotemporal optical vortex has attracted the attention of researchers due to its unique property of carrying transverse orbital angular momentum. Compared with ordinary vortex beams, it can provide additional degrees of freedom and marks a higher level of modulation of light fields. Based on the spatiotemporal-spatial optical vortex with spiral phases in both spatiotemporal and spatial domains, the spatiotemporal-spatiotemporal optical vortex and spatiotemporal-spatiotemporal-spatial optical vortex with spiral phases on two different spatiotemporal planes are numerically simulated. According to the concentric situation between different vortices in the usual spatiotemporal optical vortex, by introducing parameters to modulate the position of the center of the spatiotemporal domain vortex, we have achieved the goal of eccentricity between different vortices and numerically simulated eccentric double vortex and eccentric triple vortex. This research enriches the mode of spatiotemporal optical vortices and provides a theoretical basis for their subsequent research.
Laser & Optoelectronics Progress
- Publication Date: Mar. 10, 2024
- Vol. 61, Issue 5, 0526002 (2024)
Analysis Of Beam Transformation of Biaxial Conical Mirror
li Tian, Yuli Lou, and Siqi Liu
Based on the axial cone mirror and the Rayleigh-Sommerfeld vector diffraction theory, a detailed theoretical analysis of the generation of non-diffracted light and the light field after the generation is carried out. The spatial light field distribution and the on-axis light intensity distribution curve of the two non-diffracted beams are simulated by numerical simulation, and based on the processing technology of the conical mirror, the light field analysis of the conical angle of the conical mirror and the beam emitted from the first and second axis conical mirrors are carried out. The results show that when the conical angle of the first-axis conical mirror is smaller than that of the second-axis conical mirror, the light intensity of the outgoing beam in the interference coincidence region is a coupled superposition of the two parts of the light field, and a new non-diffracted beam is generated; conversely, the two diffraction-free beams do not coincide and continue to maintain their respective non-diffracted characteristics. Second, the outgoing beams are distributed in concentric rings along a cross-section perpendicular to the transmission direction, and the radius of the concentric rings varies with the transmission distance. In this paper, the intensity distribution, beam distribution and ring diameter of the two non-diffracted beams are tuned both theoretically and numerically, which is an important guideline for the application of non-diffracting beams in large scale space precision measurements and particle micromanipulation. Based on the axial cone mirror and the Rayleigh-Sommerfeld vector diffraction theory, a detailed theoretical analysis of the generation of non-diffracted light and the light field after the generation is carried out. The spatial light field distribution and the on-axis light intensity distribution curve of the two non-diffracted beams are simulated by numerical simulation, and based on the processing technology of the conical mirror, the light field analysis of the conical angle of the conical mirror and the beam emitted from the first and second axis conical mirrors are carried out. The results show that when the conical angle of the first-axis conical mirror is smaller than that of the second-axis conical mirror, the light intensity of the outgoing beam in the interference coincidence region is a coupled superposition of the two parts of the light field, and a new non-diffracted beam is generated; conversely, the two diffraction-free beams do not coincide and continue to maintain their respective non-diffracted characteristics. Second, the outgoing beams are distributed in concentric rings along a cross-section perpendicular to the transmission direction, and the radius of the concentric rings varies with the transmission distance. In this paper, the intensity distribution, beam distribution and ring diameter of the two non-diffracted beams are tuned both theoretically and numerically, which is an important guideline for the application of non-diffracting beams in large scale space precision measurements and particle micromanipulation.
Laser & Optoelectronics Progress
- Publication Date: Mar. 10, 2024
- Vol. 61, Issue 5, 0526001 (2024)
Cross-Polarization Effects Near the Exceptional Points (Invited)
Jin Yang, Shuaijie Yuan, Xuquan Liu, and Xinxing Zhou
We construct a propagation model of Gaussian beam in non-Hermitian system and explore the cross-polarization effects near the exceptional points in parity-time symmetric (PT-symmetric) structure. The results show that when the light beam is incident near the exceptional points, the cross-polarization component shows a double-peak intensity distribution similar to the first-order Hermite-Gaussian model. Conversely, the original polarization component shows a double-peak intensity distribution similar to the single circularly polarized components, which are perpendicular to the cross-polarization component. By adjusting the incident polarization angle, a significant rotation of the cross-polarization component near the exceptional point is revealed. Moreover, the direction of rotation of the cross-polarization component is reversed when the system crosses the exceptional points, providing a novel idea to precisely explore the position of the exceptional points. Finally, the strong cross-polarization effects near the exceptional points provide a theoretical guide for enhancing the photonic spin Hall effect. We construct a propagation model of Gaussian beam in non-Hermitian system and explore the cross-polarization effects near the exceptional points in parity-time symmetric (PT-symmetric) structure. The results show that when the light beam is incident near the exceptional points, the cross-polarization component shows a double-peak intensity distribution similar to the first-order Hermite-Gaussian model. Conversely, the original polarization component shows a double-peak intensity distribution similar to the single circularly polarized components, which are perpendicular to the cross-polarization component. By adjusting the incident polarization angle, a significant rotation of the cross-polarization component near the exceptional point is revealed. Moreover, the direction of rotation of the cross-polarization component is reversed when the system crosses the exceptional points, providing a novel idea to precisely explore the position of the exceptional points. Finally, the strong cross-polarization effects near the exceptional points provide a theoretical guide for enhancing the photonic spin Hall effect.
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2024
- Vol. 61, Issue 3, 0326002 (2024)
Research Progress in Terahertz Liquid Photonics (Invited)
Xiang Lian, Minghao Zhang, Guoyang Wang, and Liangliang Zhang
The use of liquids as terahertz (THz) wave emitters and detectors has been historically avoided due to the high absorption of polar liquids in the THz range, especially liquid water. This hinders the development of THz liquid photonics. Compared with other matter states, liquids exhibit numerous unique properties. In particular, liquids have a material density comparable to that of solids, meaning that the number of molecules interacting with laser pulses is three times higher than that of gas. In contrast to solids, liquid fluidity allows each laser pulse to interact with a fresh target area. Therefore, the material damage threshold is not an issue even with high repetition rate laser pulses. This makes liquids very promising candidates for studying high-energy-density plasma and ultrafast dynamics of ionized particles in laser-matter interaction. THz liquid photonics is an emerging topic, offering an alternative for researchers to obtain THz emission from liquid material. This interdisciplinary and transformative topic will enable new science and advance numerous THz wave sensing and spectroscopy technologies that significantly impact THz technology, including next-generation liquid source, device, and system development. The use of liquids as terahertz (THz) wave emitters and detectors has been historically avoided due to the high absorption of polar liquids in the THz range, especially liquid water. This hinders the development of THz liquid photonics. Compared with other matter states, liquids exhibit numerous unique properties. In particular, liquids have a material density comparable to that of solids, meaning that the number of molecules interacting with laser pulses is three times higher than that of gas. In contrast to solids, liquid fluidity allows each laser pulse to interact with a fresh target area. Therefore, the material damage threshold is not an issue even with high repetition rate laser pulses. This makes liquids very promising candidates for studying high-energy-density plasma and ultrafast dynamics of ionized particles in laser-matter interaction. THz liquid photonics is an emerging topic, offering an alternative for researchers to obtain THz emission from liquid material. This interdisciplinary and transformative topic will enable new science and advance numerous THz wave sensing and spectroscopy technologies that significantly impact THz technology, including next-generation liquid source, device, and system development.
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2024
- Vol. 61, Issue 3, 0326001 (2024)
Generations of Structured Light (Invited)
Yan Zhang, and Tong Nan
A structural beam refers to a light field that is"customized"in both space and time, characterized by its unique distribution of amplitude, phase, and polarization state in both space and time. Recently, research on structured light beams has developed rapidly. This has led to the evolution of a special distribution of optical parameters from specific spatial transverse and longitudinal structures to customized spatiotemporal structures. This type of beam with different spatiotemporal structures has brought breakthroughs in many fields, including optical communication, optical sensing, optical micromanipulation, quantum information processing, and super-resolution imaging. Therefore, various methods have been proposed, and related devices have been manufactured to generate structured light beams by adjusting the distribution of various optical parameters of the beam in spatial and spatiotemporal domains. This study mainly introduces the preparation methods for different types of structured light beams, such as spatially structured and spatiotemporal structured beams. Therefore, it provides a comprehensive overview of the generated structured beams, along with a discussion and outlook on the future development direction of structured beams. A structural beam refers to a light field that is"customized"in both space and time, characterized by its unique distribution of amplitude, phase, and polarization state in both space and time. Recently, research on structured light beams has developed rapidly. This has led to the evolution of a special distribution of optical parameters from specific spatial transverse and longitudinal structures to customized spatiotemporal structures. This type of beam with different spatiotemporal structures has brought breakthroughs in many fields, including optical communication, optical sensing, optical micromanipulation, quantum information processing, and super-resolution imaging. Therefore, various methods have been proposed, and related devices have been manufactured to generate structured light beams by adjusting the distribution of various optical parameters of the beam in spatial and spatiotemporal domains. This study mainly introduces the preparation methods for different types of structured light beams, such as spatially structured and spatiotemporal structured beams. Therefore, it provides a comprehensive overview of the generated structured beams, along with a discussion and outlook on the future development direction of structured beams.
Laser & Optoelectronics Progress
- Publication Date: Jan. 10, 2024
- Vol. 61, Issue 1, 0126001 (2024)
Numerical Analysis of the Band Structure of Two-Dimensional Dispersive Dielectric Photonic Crystals
Xianghui Zhong, and Jianhua Yuan
In this study, the characteristics of two-dimensional dispersive dielectric photonic crystals are studied via a numerical approach that combines the finite-element method (FEM) with Newton's iterative method. For a dispersive photonic crystal whose permittivity is dependent on the frequency, the band structure problem is formulated as a nonlinear eigenvalue problem. In this study, first, a discrete variational formulation is derived from Maxwell's equations based on the FEM. Thereafter, by selecting approximate solutions as the initial values for the iteration, this nonlinear problem is solved for different values of the wave vector k based on Newton's iterative method. Consequently, the band structure of dispersive dielectric photonic crystals is obtained numerically. Several dispersive photonic crystals in the transverse electric (TE) and transverse magnetic (TM) modes are investigated. The numerical results reveal that the proposed method is effective for dispersive photonic crystals. In this study, the characteristics of two-dimensional dispersive dielectric photonic crystals are studied via a numerical approach that combines the finite-element method (FEM) with Newton's iterative method. For a dispersive photonic crystal whose permittivity is dependent on the frequency, the band structure problem is formulated as a nonlinear eigenvalue problem. In this study, first, a discrete variational formulation is derived from Maxwell's equations based on the FEM. Thereafter, by selecting approximate solutions as the initial values for the iteration, this nonlinear problem is solved for different values of the wave vector k based on Newton's iterative method. Consequently, the band structure of dispersive dielectric photonic crystals is obtained numerically. Several dispersive photonic crystals in the transverse electric (TE) and transverse magnetic (TM) modes are investigated. The numerical results reveal that the proposed method is effective for dispersive photonic crystals.
Laser & Optoelectronics Progress
- Publication Date: May. 10, 2023
- Vol. 60, Issue 9, 0926001 (2023)
Study on Closed-Loop Stability Control of Fast Axis Adjustable Photoelastic Modulator
Xiaoyang Zang, Kewu Li, Zhibin Wang, Kunyu Li, Zhenkun Liang, and Kun Liu
Fast axis ajustable photoelastic modulator (FaaPEM) not only has the advantages of high modulation frequency, large aperture, and good seismic performance, but also makes up for the shortcomings of traditional elastic optical modulator, such as phase delay and fast axis azimuth. It plays an important role in polarization modulation and polarization measurement. FaaPEM is a resonant optomechanical device composed of two piezoelectric drivers and elastic optical crystals. In the high voltage resonant state, due to its own temperature rise, the resonant frequency of elastic optical crystals does not match the frequency of driving voltage, which greatly affects the modulation efficiency of incident light. In order to ensure the optimal modulation capability and stability of FaaPEM at work, this paper carries out the research on the stable closed-loop control of FaaPEM, proposes a closed-loop drive control method based on modulation signal tracking and phase regulation, and tests the stability of FaaPEM. The test results show that the stability of the system reaches 4.18% under half wave state and 3.43% under quarter wave state after loading feedback control. Fast axis ajustable photoelastic modulator (FaaPEM) not only has the advantages of high modulation frequency, large aperture, and good seismic performance, but also makes up for the shortcomings of traditional elastic optical modulator, such as phase delay and fast axis azimuth. It plays an important role in polarization modulation and polarization measurement. FaaPEM is a resonant optomechanical device composed of two piezoelectric drivers and elastic optical crystals. In the high voltage resonant state, due to its own temperature rise, the resonant frequency of elastic optical crystals does not match the frequency of driving voltage, which greatly affects the modulation efficiency of incident light. In order to ensure the optimal modulation capability and stability of FaaPEM at work, this paper carries out the research on the stable closed-loop control of FaaPEM, proposes a closed-loop drive control method based on modulation signal tracking and phase regulation, and tests the stability of FaaPEM. The test results show that the stability of the system reaches 4.18% under half wave state and 3.43% under quarter wave state after loading feedback control.
Laser & Optoelectronics Progress
- Publication Date: Apr. 10, 2023
- Vol. 60, Issue 7, 0726003 (2023)
Visual Inertial Navigation System Aided by Polarized Light
Jinkui Chu, Hanpei Hu, Zhenhua Wan, and Jinshan Li
To improve the reliability of the integrated navigation system and the accuracy of pose estimation, a novel visual inertial integrated navigation system assisted by polarized light is proposed and constructed by introducing a polarization orientation sensor into the process of simultaneous localization and mapping. The data from the polarization orientation sensor, monocular vision camera, and micro-inertial measurement unit are collected. The target equation is established using the least square optimization method after multi-sensor data has been time-stamped aligned and preprocessed, and the best motion estimation is then produced by solving nonlinear equations. In the suggested system, the observability of azimuth is achieved based on the polarization distribution of the sky, and multi-sensor data are fused. Based on the above-integrated navigation system, an outdoor vehicle-mounted experiment is carried out. The experimental findings indicate that, in the long-distance operation of 2 km, the location inaccuracy of the polarized light-assisted visual-inertial navigation system is 16.7% lower and the heading angle accuracy is 23.4% greater than the estimated value of the original visual-inertial system. The polarization orientation sensor can reduce the drift of inertial devices, enhance the position accuracy and attitude angle accuracy of the navigation system, and meet the needs of the position and pose estimation accuracy and reliability under the interference of satellite signals. To improve the reliability of the integrated navigation system and the accuracy of pose estimation, a novel visual inertial integrated navigation system assisted by polarized light is proposed and constructed by introducing a polarization orientation sensor into the process of simultaneous localization and mapping. The data from the polarization orientation sensor, monocular vision camera, and micro-inertial measurement unit are collected. The target equation is established using the least square optimization method after multi-sensor data has been time-stamped aligned and preprocessed, and the best motion estimation is then produced by solving nonlinear equations. In the suggested system, the observability of azimuth is achieved based on the polarization distribution of the sky, and multi-sensor data are fused. Based on the above-integrated navigation system, an outdoor vehicle-mounted experiment is carried out. The experimental findings indicate that, in the long-distance operation of 2 km, the location inaccuracy of the polarized light-assisted visual-inertial navigation system is 16.7% lower and the heading angle accuracy is 23.4% greater than the estimated value of the original visual-inertial system. The polarization orientation sensor can reduce the drift of inertial devices, enhance the position accuracy and attitude angle accuracy of the navigation system, and meet the needs of the position and pose estimation accuracy and reliability under the interference of satellite signals.
Laser & Optoelectronics Progress
- Publication Date: Apr. 10, 2023
- Vol. 60, Issue 7, 0726002 (2023)
Simulated Generation of Perfect Polarization Singularity Light Fields
Dong Ye, Zongchen Li, Yi Zhang, Junyao Li, and Yining Ma
Recently, perfect vortex beams have been proposed and studied. Therefore, in this paper, we combine perfect vortex beams and polarization singularities to generate perfect polarization singularity light fields by superimposing two orthogonal circularly polarized perfect Laguerre-Gaussian beams with different topological charges. The results show that the radius of the perfect singular field is much smaller than that of the conventional singular field. We also study the superposition of orthogonal circularly polarized perfect Laguerre-Gaussian and conventional Laguerre-Gaussian beams for different cases. Consequently, we obtain that the polarization states of the superimposed light fields are different, and the phenomenon of “quasi-high-order polarization singularities” appears. Moreover, the simulation of perfect singularities has broadened the theoretical study of singular optics. Recently, perfect vortex beams have been proposed and studied. Therefore, in this paper, we combine perfect vortex beams and polarization singularities to generate perfect polarization singularity light fields by superimposing two orthogonal circularly polarized perfect Laguerre-Gaussian beams with different topological charges. The results show that the radius of the perfect singular field is much smaller than that of the conventional singular field. We also study the superposition of orthogonal circularly polarized perfect Laguerre-Gaussian and conventional Laguerre-Gaussian beams for different cases. Consequently, we obtain that the polarization states of the superimposed light fields are different, and the phenomenon of “quasi-high-order polarization singularities” appears. Moreover, the simulation of perfect singularities has broadened the theoretical study of singular optics.
Laser & Optoelectronics Progress
- Publication Date: Apr. 10, 2023
- Vol. 60, Issue 7, 0726001 (2023)
Topics
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20