Electrically and magnetically controlled optical spanner based on the transfer of spin angular momentum of light in an optically active medium
Electrically and magnetically controlled optical spanner based on the transfer of spin angular momentum of light in an optically active medium
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基于光学活性介质中光自旋角动量传递的电磁控制光学扳手
DOI：
10.1103/physreva.75.061403
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发表时间：
2007-06-01
影响因子：
2.9
通讯作者：
She, Weilong
中科院分区：
文献类型：
--
作者：
Chen, Lixiang;Zheng, Guoliang;She, Weilong
光学扭矩是一种可以对物体施加扭矩的光束。在这种快速通信中，证明了在施加的电场和磁场的帮助下，具有初始线性偏振和初始为零的总自旋角动量的光束可以与光学活性介质相互作用，导致左旋圆偏振光子与右旋圆偏振光子的比率发生变化。因此，光的总自旋角动量改变，这导致扭矩，在介质上产生电和磁控制的光学扭矩。对于632.8 nm线偏振激光束入射到100 μ m长、半径为5 μ m的Ce：Bi 12 TiO 20晶须晶体上，当磁场固定在-1.8 T时，左（右）手圆偏振光子数和总自旋角动量都随外加电场呈正弦变化，这意味着光学晶体施加在晶体上的力矩也随电场呈正弦变化。结果表明，在50（或-50）kV/cm时，56%的右（左）旋圆偏振光转换为左（右）旋圆偏振光，相当于多个光子贡献0.56（{Dirac_h}/2{pi}）的自旋角动量.«少
An optical spanner is a light beam that can exert a torque on an object. It is demonstrated in this Rapid Communication that, with the aid of applied electric and magnetic fields, a light beam with initially linear polarization and initially zero total spin angular momentum can interact with an optically active medium, resulting in a change of the ratio of left-handed circularly polarized photons to right-handed ones. Thus the total spin angular momentum of the light is changed, which leads to a torque, creating an electrically and magnetically controlled optical spanner on the medium. For a linearly polarized 632.8 nm laser beam incident on a 100-{mu}m-long Ce:Bi{sub 12}TiO{sub 20} whisker crystal with 5 {mu}m radius, if the magnetic field is fixed at -1.8 T, both the left- (right-)handed circularly polarized photon number and the total spin angular momentum vary with the applied electric field in a sinusoidal way, which means the torque exerted by the optical spanner on the crystal also varies sinusoidally with the electric field. It is found that at 50 (or-50) kV/cm, 56% right- (left-)handed circularly polarized photons are translated into left- (right-)handed ones, which corresponds to a transfer of 0.56({Dirac_h}/2{pi}) spin angular momentum contributed bymore » each photon.« less