摘要
本文提出了线性吸收介质非局域线性电光效应的耦合波理论,建立了相应的耦合波方程组,并求解了该方程组.由此,可给出在任意方向外加电场的作用下,光在具有空间非局域响应的线性吸收介质中沿任意方向传播时出射光场的表达式.据此,研究了线性吸收是如何改变出射光场的两个偏振分量的振幅、相位和波形的.进一步讨论了线性吸收对电光强度调制的影响,以及如何测量一阶线性和二阶非线性极化率非局域响应的特征长度和介质的线性吸收系数.
Being an important optical phenomenon,the linear electro-optic effect has diverse applications in the optical modulation and optical switching.The refractive index ellipsoid theory has been widely used to study the linear electro-optic effect for a long time.Despite of its visualization such a theory has limitations and cannot deal with a lot of cases in which the linear absorption cannot be neglected,or the electric displacement vector has a nonlocal response to electric field,etc.To overcome such shortcomings,in 2001 a wave coupling theory of linear electro-optic effect was developed by She and Lee（She W,Lee W 2001 Opt.Commun.195 303）.And in 2016 we generalized this wave coupling theory to the treatment of nonlocal linear electro-optic effect in which the displacement vector has a nonlocal response to electric field.In this paper,we use this wave-coupling theory to investigate how the linear absorption influences the linear electro-optic effect in a nonlocal medium.Starting from Maxwell＇s equations and considering the linear absorption and the nonlocality of the susceptibility tensors,we obtain two coupling equations for two orthogonal linear polarized waves and also analytical solutions of the resulting equations,which can be used to describe the nonlocal linear electro-optic effect for a light beam propagating along any direction,with an external direct current electric field applied along an arbitrary direction in a linear absorbent crystal.With such solutions,we study the influences of the linear absorption on the phase,amplitude,shape of the output beam,as well as the half-wave voltage and the extinction ratio of electro-optic modulation.The results show that no matter whether there exists linear absorption,the Rayleigh distance of the Gaussian beam in the crystal will be shortened as a result of the nonlocality of χ^-（1）.When linear-absorption coefficients α11 and α22 are equal,the linear absorption damps equally the amplitudes of the two polarized output beams with keeping their phases and s
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2017年第6期107-116,共10页
Acta Physica Sinica
基金
国家自然科学基金(批准号:11274401)资助的课题~~
关键词
线性电光效应
非局域
线性吸收
电光调制
linear electro-optic effect
nonlocal
linear absorption
electro-optic modulation
