Ferroelectric Liquid-crystal Light Modulator Research Articles

High speed partial Stokes imaging using a ferroelectric liquid crystal modulator

This paper describes the implementation of an imaging polarimeter using a single ferroelectric liquid crystal light modulator. It provides partial imaging Stokes information at 234 Hz, much faster than polarimeters using nematic light modulators. This information is obtained for dynamic scenes in reflection or transmission. Partial Stokes information contains the first three Stokes parameters. With this information, imaging of the linear degree of polarization and of the angle of polarization can be obtained and imaging linear depolarization can be quantified.

Edge enhancement recording with ferroelectric liquid crystal spatial light modulator using SiO2/a-Si:H photosensor

Abstract Photo-addressed ferroelectric liquid crystal light modulators (FLC-SLM) are used for optical data processing and display system as binary devices. We have found an edge enhancement effect in our binary FLC-SLM under certain conditions of applied bipolar voltage. We demonstrate this edge enhancement effect in binary FLC-SLM and discuss the origin of this effect.

The theoretical design and fabrication of a prism-coupled polarization conversion ferroelectric liquid crystal light modulator

It is possible to probe directly the optical dielectric tensor configuration within thin smectic layers (less than 6 μm thick) of ferroelectric liquid crystals (FLCs) by the propagation of optical prism-coupled leaky Fabry-Pérot modes. Incident polarized monochromatic light couples into the resonant modes of the system and may be coupled out of the cell in an orthogonal polarization. The observed reflectivity is a series of sharp peaks on a low background response at certain well-defined incident angles. These sharp resonant features make the prism-coupling technique a possible route for commercial fabrication of voltage-modulated devices. However, previous prism-coupled cells with sharp resonant guided mode features are not practical from a device point of view because they incorporate silver layers not used in conventional cell design. In this paper we demonstrate for the first time operating a leaky guided mode FLC cell with conventional surface layers, in a sp-mixed polarization mode of operation, allows sharp features to be observed which are modulated in intensity by an applied d.c. voltage. The prism-coupled cells used here are designed to be compatible with current FLC device technology.

A New Optical Neuron Device for All-Optical Neural Networks

A new optical neuron device has been developed. The device can perform both summation and thresholding operations in optics, and consists of a PIN a-Si:H photoreceptor, aluminum neuron electrodes and a ferroelectric liquid crystal light modulator. The a-Si:H photoreceptor shows characteristics of an ideal quantum efficiency (η∼1) and a good linearity (γ∼1). The optical neuron device exhibits a response time of ∼30 µs for incident light power of 9 µW and a contrast ratio of 300:1. Using this neuron device, a lenslet array and a memory mask, an all-optical neural network has been constructed. The network demonstrates an associative memory function on purely optical parallel processing without any help from electric computation.

Photovoltaic optically addressed spatial light modulator

Abstract We present the physical structure of and experimental results on a photovoltaic optically addressed spatial light modulator. The device is composed of a photosensor with a stack of four p - i - n photodiodes and a ferroelectric liquid crystal light modulator. The spatial resolution is 20 lp/mm 2 and the ON/OFF contrast ratio is 10:1. An optical novelty filtering system using this device is also presented.

Operating Characteristics of Optically Addressed Spatial Light Modulators Incorporating Distorted Helix Ferroelectric Liquid Crystals

Distorted helix ferroelectric liquid crystals have received attention recently due to the availability of short-pitch, high-spontaneous-polarization mixtures. In this paper we discuss the operating characteristics of an optically addressed spatial light modulator incorporating a hydrogenated amorphous silicon photosensor and a distorted-helix ferroelectric liquid crystal light modulator. The device exhibits a grey-scale response over a range of write-light intensities which depends on operating frequency. The spatial resolution is 30 lp/mm. The time-averaged contrast ratio is 7:1, limited primarily by non-uniformity in the liquid crystal alignment. During switching, both the average optic axis orientation and the effective birefringence of the liquid crystal change. The capability of the device to produce a pseudocolored readout image is attributed to the latter effect.

Optical crossbar switch and optical vector-matrix multiplier based on ferroelectric liquid crystal light modulator

Abstract The optical vector-matrix processor represent an important element on the way towards hybrid electronic-output parallel computing. A two dimensional spatial light modulator is the heart of such processors. Present modulators based on nematic liquid crystals offer speeds in the range of 10–100 Hz. A ferroelectric liquid crystal based light modulator promises speeds exceeding 1 kHz with spatial resolution of 106 elements.