RU1803900C - Spatial-time light modulator - Google Patents

Abstract

Usage: conversion of the spectrum, coherence and energy of optical images. The inventive spatio-temporal modulator is made in the form of sequentially located between glass substrates with transparent electrodes connected to a voltage source, a two-layer photoconductor wafer, the first layer of which is transparent in a given wavelength range, and the second, which is in contact with a dielectric mirror is made with impurity conductivity sensitive to radiation in a given wavelength range and a liquid crystal layer. 1 ill.

Description

The invention relates to instruments for controlling the intensity of light made on liquid crystals and intended for conversion by the spectrum, coherence and energy of optical images.

The aim of the invention is to increase the resolution.

The drawing shows a schematic diagram of the claimed device. Here

1 - the first glass on the substrate:

2 - the first transparent electrode;

3 - a layer of a semiconductor wafer, transparent in a given wavelength range (substrate);

4 - a layer of a semiconductor wafer with impurity photoconductivity (photosensitive layer);

5 - dielectric mirror;

6 - liquid crystal;

7 - second transparent electrode;

8 - a second glass substrate;

9 is a voltage source.

The recorded optical image is projected onto the PVMS from the side of the first glass substrate. Luminous flux from the wavelength range Ai (Ai is the wavelength of the edge of the fundamental absorption of the material of the semiconductor wafer; H2 is the wavelength of the edge of the impurity absorption in layer 4), the glass substrate 1, the transparent electrode 2, and the layer of the semiconductor wafer 3 pass freely. In the layer with impurity photoconductivity 4, light is absorbed and current carriers are generated, which are separated by the electric field generated by the voltage source 9. The current carriers of the same sign (free current carriers) are injected into spoon, and carriers of the opposite sign current (ionized impurity) are bound and form a volumetric charge which generates a charge pattern on the layer of the LCD 6, and

ate

with

with

about

Cj

y u

this, in turn, leads to the formation of the corresponding relief of the optical properties of the LC layer.

The read luminous flux is directed to the PVMS from the side of the LCD layer 6. It passes through the second glass substrate 8, the second transparent electrode 7, and the LCD layer 6, after reflection from the dielectric mirror 5, the light flux passes through the LC 6 layer, the transparent electrode 7, and the glass layer a second time substrate 8. In this case, the reading light flux is spatially modulated by the LC layer in intensity, phase, or polarization, depending on the properties of the applied LC,

The volume charge formed by the coupled current carriers spreads at a speed determined by the Maxwell relaxation time Tre, where p is the resistivity of the photosensitive layer and а is its dielectric constant. For wide-gap semiconductor 4 s, which is much longer than the spreading time of free current carriers (10 s).

The use of a semiconductor with an impurity photoconductivity in a PVMS with a two-layer PLL as a photosensitive layer and the location of this layer on the side facing the LC (at the boundary with the dielectric mirror) allows increasing the resolution of the PVMS by reducing the rate of spreading of the volume charge, which forms a potential relief on the LCD. In addition, there is no potential barrier at the interface between the photosensitive layer and the substrate, which is inevitable even in an ideal heterojunction due to band gap.

The proposed PVMS operating in the infrared wavelength range is implemented as follows.

The semiconductor wafer was made of semi insulating gallium arsenide. IR sensitive

layer 4 is formed in a gallium arsenide plate by introducing defects with deep energy levels, for example, proton bombardment. Transparent

the electrodes 2 and 7 were made of SnOz, and the dielectric mirror 5 of successively alternating 10-20 layers of SiOa and TiOa. Nematic liquid crystal was used as LC layer 6. The voltage source of the PVMS was a low-frequency sinusoidal voltage generator.

In the process of implementing the invention, PVMS with the following

characteristics; gallium arsenide plate thickness 400 μm; the thickness of the nematic LC layer is 5 μm; electro-optical effect S-effect; power supply voltage 50 V; power frequency 200 Hz; the sensitivity range of PVMS is 0.9-1.5 microns; integrated sensitivity W / cm2; resolution 70 lines / mm.

Claims (1)

The claims A spatio-temporal light modulator comprising a multilayer structure made in the form of a sequentially arranged glass substrate, a first transparent electrode, a two-layer semiconductor wafer, a dielectric mirror, a liquid crystal, a second transparent electrode, a second glass substrate, the electrodes being connected to a voltage source characterized in that, in order to increase the resolution. ability, a two-layer semiconductor wafer is made of one semiconductor material, the layer contacting with a dielectric mirror, is made with impurity photoconductivity sensitive to radiation in a given wavelength range, and the second layer is transparent in the same wavelength range. A 5 $ 7 &