光悬浮微粒子旋转特性研究  

Investigation of rotation characteristics of optically levitated particles

作　　者：曾凯 蒲俊吉 吴宇列[1] 肖定邦[1] 吴学忠[1] ZENG Kai;PU JunJi;WU YuLie;XIAO DingBang;WU XueZhong(College of Intelligence Science and Technology,National University of Defense Technology,Changsha 410073,China)

机构地区：[1]国防科技大学智能科学学院,长沙410073

出　　处：《中国科学：技术科学》2023年第8期1351-1359,共9页Scientia Sinica(Technologica)

基　　金：国家自然科学基金(批准号:51975579)资助项目。

摘　　要：悬浮光机械系统将微粒子悬浮在空中,较好地隔绝了环境噪声,在诸多精密测量及量子科学领域都发挥着重要作用.利用圆偏振激光驱动微粒子自旋,可以进行扭矩测量、气体辨识及真空摩擦等方面的研究.本文基于光悬浮微粒子旋转动力学模型,搭建了真空光悬浮及旋转实验装置,对悬浮粒子的平均转速和转速波动进行了研究.结果表明,影响光力矩的激光功率越强,激光偏振态越接近圆偏振光,粒子的平均转速则越大.但影响粒子平均转速的主要因素是阻尼力矩,通过降低环境气压以减小粒子的旋转阻尼,其平均转速可大幅提升.通过调控这些实验参数,约4μm直径的球霰石微球在环境气压为0.1 Pa时被驱动至3.93 MHz转速.但在低气压环境下,微粒子的热运动也变得明显,从而导致悬浮粒子的等效激光功率随着热运动而变化,进而使得粒子的转速波动也随着气压的下降而增大.本文首创性地对比了相同气压不同转速下的转速波动,进一步说明了粒子热运动对转速波动的影响规律.此外,本文还研究了不同气压下转速相对波动的变化规律,这为光悬浮转子在陀螺仪领域的潜在应用奠定了基础.这些研究结果对于提升光悬浮系统已有应用以及开拓新领域均有重要意义.A levitated optomechanical system levitates particles in the air or vacuum,which insulates the environment noise well and plays an important role in many fields related to precision measurement and quantum science.This system uses a circularly polarized laser to drive particles to spin,which can carry out research on torque measurement,gas identification,and vacuum friction.This paper describes a vacuum optical levitation and rotation experimental device based on the rotating dynamics model of optically levitated particles.The average speed and fluctuation of the rotational speed of levitated particles are studied.The results show that the stronger the laser power that affects the optical torque and the closer the laser polarization is to the circularly polarized light,the greater the average rotational speed of particles.However,the main factor that affects the average rotational speed of particles is the damping torque.The average rotational speed can be increased by reducing the ambient pressure to reduce the rotational damping of particles.When the pressure decreases to 0.1 Pa,we drive the spherical vaterite microsphere with a diameter of 4μm at a speed of 3.93 MHz.Simultaneously,in a low-damping environment,the thermal motion of particles also becomes obvious,resulting in a change in the equivalent laser power of levitated particles with the thermal motion.Subsequently,the rotational speed fluctuation also increases with pressure decrease.This paper,for the first time,investigated the rotational frequency fluctuation under unchanged pressure and varying mean rotational frequency.These conditions further illustrate the effect of thermal motion on rotational frequency.Besides,the relative fluctuation of rotation with changing pressure is investigated,and the results allow for the potential application of optically levitated rotors in the field of gyroscopes.These results are of great significance for improving the existing applications of optical levitation systems and opening new fields.

关 键 词：悬浮光机械系统 光致旋转 超快旋转 转速稳定性 

分 类 号：O43[机械工程—光学工程]