An electrically tunable-focusing liquid crystal lens with a low voltage and simple electrodes

We propose a reactive mesogen (RM) lens array to obtain good focusing behavior along with a short focal plane, where the focusing behavior is switchable according to the polarization state of incident light. Polarization-dependent focusing behavior is obtained using a planoconvex RM microlens array on a planoconcave isotropic lens template. Even though the sagitta of our RM lens is high, to obtain the short focal length, the RM layer can be aligned well by introducing a top-down alignment effect, using a nanogrooved template. The optical noise due to the moiré effect generated by the nanogrooves on the surface of the planoconvex RM layer can be removed simply by overcoating a thin RM layer, which is self-aligned by the geometric surface effect, without an additional alignment process. We demonstrate a hexagonal-packed RM lens array that has a very high fill factor and symmetric phase profile, for an ideal lens.

show abstract

“…An RM lens can be made on a single substrate, which enables the fabrication of an applicable thin-film optical element [15,16].…”

Section: Introductionmentioning

confidence: 99%

Polarization-Dependent Microlens Array Using Reactive Mesogen Aligned by Top-Down Nanogrooves for Switchable Three-Dimensional Applications

Son

Kim

Park

2015

Journal of the Optical Society of Korea

View full text Add to dashboard Cite

show abstract

“…The LC lens in this paper still requires high applied voltages. This can be solved by using many other structures of LC lens operated with a driving voltage below 10 V rms [10,21]. Moreover, the optical efficiency can be enhanced by using polarization independent LC phase modulator, including double layered type, residual phase type or mixed type [17,20,[22][23][24][25][26][27][28][29][30].…”

Section: Experiments and Discussionmentioning

confidence: 99%

An Electrically Tunable Liquid Crystal Lens for Fiber Coupling and Variable Optical Attenuation

Lin¹

2014

J Elec Electron Syst

View full text Add to dashboard Cite

In this paper, an electrically tunable LC lens for fiber coupling and variable optical attenuation is proposed and demonstrated. The LC lens electrically changes the lens power in order to adjust the beam size incident on the fiber. When the beam size is closed to the core size of the fiber, the LC lens is operated as a lens coupler. When the beam size increases by reducing the lens power, the LC lens is operated as a VOA. After introducing the operating principles, we use a LC lens to experimentally demonstrate the design concept and the results show that the maximum coupling efficiency can be 0.75 and the maximum attenuation can be as large as18 dB. The concept proposed in this paper is not only for LC lenses, but also for other optical components with electrically tunable focusing properties. The study provides a new way to design an optical device for fiber coupling and variable optical attenuation based on electrically tunable focusing optical components. Figure 1a and 1b depict a typical structure of the LC lens with positive and negative lens operations. We use the hole-patterned LC lens to demonstrate the concept [11,12]. In fact, the concept we proposed here can be applied to other structures of LC lenses. The components of the LC lens included three Indium Tin Oxide (ITO) glass substrates, two Polyvinyl Alcohol (PVA) layers for LC alignment, an insulating layer (Norland product Inc. NOA81), and a 50 μm nematic LC layer (Merck MLC-2070, Δn=0.2609). In order to generate an inhomogeneous electric field, the ITO layer in the middle of the glass substrate was etched with a hole and connected to an applied Alternating Current (AC) voltage of V 1 . PVA layers were coated on the glass substrates and mechanically rubbed in one direction to align the LC molecules. As a result, the LC molecules are aligned parallel to the glass substrate (x-direction in Figure 1) as V 1 =V 2 =0V rms and provide zero lens power (i.e. inverse of the focal length) for x-linearly polarized light. Mechanism and Operating Principles AbstractAn electrically tunable Liquid Crystal (LC) lens for both of fiber coupling and variable optical attenuation is demonstrated. The LC lens modulates the beam waist coupling to the fiber by electrically changing the lens power. When the modulated beam waist is close to the core size of the fiber, the LC lens is operated as a lens coupler. When the beam waist increases by reducing the lens power, the LC lens is operated as a Variable Optical Attenuator (VOA) as a result of the corresponding coupling coefficient variation of the transformed beam into a multimode fiber. The study provides a way to design an optical device for fiber coupling and variable optical attenuation based on electrically tunable focusing optical component.

show abstract

“…6 Many approaches have been demonstrated to also build nematic LC (NLC) components for optical imaging. 1,[7][8][9][10][11][12][13][14][15][16][17] However, those materials have a fundamental limitation: they are polarization sensitive since the refractive index modulation here is achieved by the electrical field-induced reorientation of their local anisotropy axis (commonly called "director," representing the local average direction of the long molecular axes of the NLC 4 ). Figure 1(a) schematically demonstrates an electrically variable NLC lens using a single-layer of NLC that is in the Y; Z plane (with its ground state director being parallel with the Y-axis).…”

Section: Introductionmentioning

confidence: 99%

Focusing unpolarized light with a single-nematic liquid crystal layer

Galstian

Allahverdyan

2015

Opt. Eng

View full text Add to dashboard Cite

Abstract. We describe a simple but very efficient optical device that allows the dynamic focusing of unpolarized light using a single-nematic liquid crystal layer. The operation principle of the proposed device is based on the combination of an electrically variable "half-lens" with two fixed optical elements for light reflection and a 90-deg polarization flip. Such an approach is made possible thanks to the close integration of the thin film wave plate and mirror. Preliminary experimental studies of the obtained electrically variable mirror show very promising results. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

show abstract

An electrically tunable-focusing liquid crystal lens with a low voltage and simple electrodes

Cited by 85 publications

References 32 publications

Polarization-Dependent Microlens Array Using Reactive Mesogen Aligned by Top-Down Nanogrooves for Switchable Three-Dimensional Applications

Polarization-Dependent Microlens Array Using Reactive Mesogen Aligned by Top-Down Nanogrooves for Switchable Three-Dimensional Applications

An Electrically Tunable Liquid Crystal Lens for Fiber Coupling and Variable Optical Attenuation

Focusing unpolarized light with a single-nematic liquid crystal layer

Contact Info

Product

Resources

About