Kotova Svetlana P, Samagin Sergey A, Pozhidaev Evgeny P, Kiselev Alexei D
Lebedev Physical Institute, Leninsky Prospekt 53, 119991 Moscow, Russia.
Samara State Aerospace University, Moskovskoe Shosse 34, 443086 Samara, Russia.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Dec;92(6):062502. doi: 10.1103/PhysRevE.92.062502. Epub 2015 Dec 1.
We study both experimentally and theoretically modulation of light in a planar aligned deformed-helix ferroelectric liquid crystal (DHFLC) cell with subwavelength helix pitch, which is also known as a short-pitch DHFLC. In our experiments, the azimuthal angle of the in-plane optical axis and electrically controlled parts of the principal in-plane refractive indices are measured as a function of voltage applied across the cell. Theoretical results giving the effective optical tensor of a short-pitch DHFLC expressed in terms of the smectic tilt angle and the refractive indices of the ferroelectric liquid crystal (FLC) are used to fit the experimental data. The optical anisotropy of the FLC material is found to be weakly biaxial. For both the transmissive and reflective modes, the results of fitting are applied to model the phase and amplitude modulation of light in the DHFLC cell. We demonstrate that if the thickness of the DHFLC layer is about 50μm, the detrimental effect of field-induced rotation of the in-plane optical axes on the characteristics of an axicon designed using the DHFLC spatial light modulator in the reflective mode is negligible.
我们通过实验和理论研究了具有亚波长螺旋节距的平面排列变形螺旋铁电液晶（DHFLC）盒中的光调制，这种盒也被称为短节距DHFLC。在我们的实验中，测量了面内光轴的方位角以及面内主折射率的电控部分随施加在盒上电压的变化。给出以近晶倾斜角和铁电液晶（FLC）折射率表示的短节距DHFLC有效光学张量的理论结果用于拟合实验数据。发现FLC材料的光学各向异性为弱双轴性。对于透射和反射模式，拟合结果被用于模拟DHFLC盒中光的相位和幅度调制。我们证明，如果DHFLC层的厚度约为50μm，那么在反射模式下，面内光轴的场致旋转对使用DHFLC空间光调制器设计的轴棱锥特性的不利影响可以忽略不计。
