摘要
构建了完整的机载激光下行传输链路,用于分析低空发射激光的跨介质传输特性及其对无线能量传输系统的影响。首先,分析不同传输介质与光学系数的关系;然后,采用蒙特卡罗数值模拟法分析传输距离、海气界面风速、激光波长、束腰半径和接收器接收半径对归一化接收能量的影响。研究结果表明,粒子尺寸、悬浮物质量浓度对跨介质传输链路光学系数和粒子复折射率的影响显著,归一化接收功率随大气和水下传输距离、接收器接收半径的增大而减小,风速和束腰半径对归一化接收功率的影响不大。本文的研究结果可为激光跨介质下行无线能量传输的波长选择、光束整形和效率评估提供参考。
Objective The restricted power supply problem for equipment both on and below the sea surface has seriously affected the development of marine equipment,as well as the exploration and exploitation of marine resources.Traditional power supply methods,such as cable and resonant power supplies,come with several challenges,including limited transmission distance,complex equipment,and high costs.In contrast,laser wireless power transmission,with its advantages such as high power density and small equipment size,holds broad application prospects.However,most studies on laser transmission characteristics focus on the behavior of lasers in a single medium,and further research is needed for the successful realization of practical scenarios where airborne lasers supply power to devices on and below the sea surface.In this study,we use the Monte Carlo method to simulate and analyze the transmission characteristics of lasers in multi-medium coupling links and investigate the characteristics of lasers during cross-medium transmission.We hope that our research results and strategies will provide theoretical references for the design and implementation of cross-medium laser wireless energy transmission systems.Methods Firstly,this study analyzes the optical characteristics of different transmission media,including the atmospheric medium,air‒sea interface,and seawater medium,and models the optical coefficients of each transmission medium using relevant theories and mathematical models.Secondly,based on the medium models established by these theories and mathematical models,the Monte Carlo method is employed to simulate the entire physical process of a large number of photons transmitting through the media,obtaining statistical results that closely approximate the actual situation.Results and Discussions We analyze the relationships among transmission media,optical coefficients,and important indicators of the laser energy transmission system through simulation.In the atmospheric transmission medium,as the particle radius increases,the atmospheric optical coefficient gradually increases.Moreover,there is no obvious correlation between the total extinction coefficient and the complex refractive index,but the scattering coefficient and the absorption coefficient are positively correlated with the real and imaginary parts of the complex refractive index,respectively(Fig.2).When the laser wavelength varies within the range of 400‒700 nm,the scattering coefficient of the seawater medium gradually decreases as the wavelength increases,while the extinction coefficient first decreases and then increases.In addition,the optical coefficients of seawater increase with the mass concentration of phytoplankton or non-pigment suspended particles(Fig.3).This study provides a basis for the selection of laser wavelengths in different media.Lasers with a wavelength of 720 nm have a relatively large optical coefficient in the atmosphere and will experience greater scattering losses in the seawater medium.Blue light with a wavelength of 450 nm and green light with a wavelength of 500 nm are more suitable for use in the seawater medium(Fig.4).We also use the Monte Carlo method to conduct a qualitative analysis of photon transmission characteristics,including photon transmission trajectories(Fig.5)and the energy flow distribution of successfully received photons(Fig.6).Through quantitative analysis,it is found that the normalized received power decreases as the transmission distance increases(Fig.8).The increase in wind speed reduces photon transmittance and the degree of spot expansion without significantly affecting the laser normalized received power(Fig.9).The normalized received power changes with the increased beam waist radius when using nonconstant asymmetry factors,but an increase in the receiving radius will increase the normalized received power to a certain extent(Fig.10).Conclusions Based on the Monte Carlo method,we focus on the influence of relevant factors,such as suspended particles and wind speed at the air‒sea interface,on laser transmission characteristics throughout the entire process—from the atmosphere to the air‒sea interface and into the seawater.The research results show that when lasers are transmitted through the atmosphere,the optical coefficient increases with the size of atmospheric aerosol particles.Additionally,the scattering coefficient increases with the real part of the complex refractive index,and the absorption coefficient increases with the imaginary part of the complex refractive index.When lasers are transmitted in water,the optical coefficient increases with the mass concentration of phytoplankton and non-pigment suspended particles.The extinction coefficients of blue‒green lasers are smaller,and the extinction coefficient reaches a minimum when the wavelength is 570 nm.The normalized received power decreases with increasing transmission distance,with this decrease being more pronounced in the underwater environment.The extinction coefficients of lasers in the blue‒green and near-infrared bands are relatively low,which results in higher transmission efficiency.Both photon transmittance and the deflection angle of the photon transmission direction decrease as wind speed at the air‒sea interface increases.These changes exhibit an opposite trend compared to that of the normalized received power,leading to a minimal impact of wind speed on the normalized received power.When the asymmetry factor is constant,the trend of normalized received power is not significant for the laser beam waist radius.However,with nonconstant asymmetry factors,the trend becomes more noticeable.The normalized received power increases substantially with the radius of the receiver.These findings offer a theoretical reference for the realization of airborne laser cross-medium downlink wireless energy transmission.
作者
朱学贵
吴清潮
张淮清
余文超
刘庚建
Zhu Xuegui;Wu Qingchao;Zhang Huaiqing;Yu Wenchao;Liu Gengjian(School of Electrical Engineering,Chongqing University,Chongqing 400044,China)
出处
《光学学报》
北大核心
2025年第5期33-42,共10页
Acta Optica Sinica
基金
国家自然科学基金(U22B2095)
重庆市教委科学技术研究重点项目(KJZD-K202100102)。
关键词
激光无线能量传输
蒙特卡罗
米氏散射
跨介质
水下激光
laser wireless power transmission
Monte Carlo
Mie scattering
cross-medium
underwater laser
