Spatial phase light modulator based on the ferroelectric liquid-crystals: possibility of the device construction

Abstract

Abstract. The work investigates the possibility for building of zonal spatial phase light modulators employing the quadratic electro-optic effect in ferroelectric liquid-crystals and capable of providing modulation frequencies up to 1 kHz. The study is made through the use of numerical simulation methods and experimental modulation characteristicsOne of important challenges of modern optics is to increase the speed of control of the spatial characteristics of light fields. This task is relevant both to traditional areas of optics, including adaptive optics and holographic storage devices, and for such intensively developing fields of science and technology as holographic displays, optical manipulation of microscopic and nano-scale objects; quantum cryptography; quantum computation. As a rule for this the devices capable of pure phase modulation of light are needed. The traditional way of implementing a pure phase spatial modulation consists in the use of orientation effects in nematic liquid crystals (LC), for which characteristic frequencies are several tens of Hz. Such performance (response speed) restricts the possible scope of application for spatial light modulators (SLM) based on nematic LC. It is possible to increase in performance due to the orientation effects in ferroelectric liquid crystals (FLC) with sub-wavelength pitch of the spiral structure, in particular, orientational Kerr effect [1,2].Under this work the possibility of constructing spatial modulators of different types based on the cell with a ferroelectric liquid crystal with sub-wavelength pitch of the spiral and with the helicoid axis orientated along the substrates, is analyzed by the numerical simulation method.As soon as electric voltage is applied to the standard FLC cell with planar orientation of the main axis of the helix, then the change of the optical axis of the FLC layer direction and refractive indexes occurs. The change of the position of the optical axis of FLC in the plane perpendicular to the incident light wave direction causes the change in the state of polarization of the transmitted light. In this paper we studied the possibility of formation of light fields with the required spatial parameters in such conditions. Special attention was paid to the formation of light fields in the form of specified curves possessing orbital angular momentum.

Electro-Optical Modulation in Planar Aligned Ferroelectric Liquid Crystals with Subwavelength Helix Pitch

“…≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡ The above discussed effects of ellipticity modulation may affect the quality of the resulting light field formed by phase matrices. We estimated theoretically the possibility of formation of light fields with the required spatial parameters in such conditions, based on the calculation method described in [16,19], at  = 632.8 nm and D = 50 m. Special attention was paid to the formation of light fields in the form of specified curves possessing orbital angular momentum.…”