Pixelated liquid-crystal light valve for neural network application

Highly sensitive liquid crystal optically addressed spatial light modulator for infrared-to-visible image up-conversion

A liquid crystal optically addressed spatial light modulator based on an InGaAs photodiode array operating at low light levels is investigated in the short wavelength infrared (SWIR) spectral band to serve as a SWIR-to-visible imaging upconversion device. It consists of InGaAs/InP heterojunction photodetectors array sandwiched with a nematic LC layer. The photodiode array is composed of a 640×512  InGaAs/Inp heterojunctions, grown on InP substrate with a 15 μm pitch. Full up-converted visible images in stills and video modes were demonstrated with SWIR light intensities as low as 70  nW/cm² or less than pW/pixel. The influence of operation frequency on the performance of the device was found theoretically and experimentally to be crucial for a proper operation of the device. The optimum sensitivity and contrast of the device was found at a frequency around 70 Hz. To the best of our knowledge, this is the first time that such a high performance upconversion device is presented and that actual visible images are obtained.

Liquid-Crystal-on-Silicon for Augmented Reality Displays

In this paper, we review liquid-crystal-on-silicon (LCoS) technology and focus on its new application in emerging augmented reality (AR) displays. In the first part, the LCoS working principles of three commonly adopted LC modes—vertical alignment and twist nematic for amplitude modulation, and homogeneous alignment for phase modulation—are introduced and their pros and cons evaluated. In the second part, the fringing field effect is analyzed, and a novel pretilt angle patterning method for suppressing the effect is presented. Moreover, we illustrate how to integrate the LCoS panel in an AR display system. Both currently available intensity modulators and under-developing holographic displays are covered, with special emphases on achieving high image quality, such as a fast response time and high-resolution. The rapidly increasing application of LCoS in AR head-mounted displays and head-up displays is foreseeable.

Liquid crystal high-resolution optically addressed spatial light modulator using a nanodimensional chalcogenide photosensor

The fabrication and performance of an optically addressed spatial light modulator (OASLM) based on nematic liquid crystal and nanodimensional amorphous arsenic trisulfide (a-As2S3) chalcogenide glassy films are described. The photoconductive a-As2S3 layers are used both as photoalignment material and as a photosensor. The use of the OASLM as a color converter is demonstrated in the transmission mode. The phase retardation dynamic range is over 3π. Diffraction efficiency measurements show a high resolution (150 lp/mm at 50% MTF). A wide variety of materials from the chalcogenide glass (ChG) family are useful for simple fabrication of high-resolution OASLMs depending on the desired wavelength.