Tunable narrow-band pass filter based on polymer dispersion liquid crystal material

Abstract

A tunable narrow-band pass filter based on a polymer dispersion liquid crystal (PDLC) material is formed by combining an electric control photorefractive property of the PDLC material with a guided-mode resonance filter together, wherein, the guided-mode resonance filter is prepared by the following steps: sequentially placing upwards a semiconductor transparent conducting film indium tin oxide (ITO) layer and an optical grating layer on a substrate layer, coating a PDLC pre-polymerization material layer on the optical grating layer, curing the pre-polymerization material layer to obtain a PDLC layer, and plating the ITO layer on the PDLC layer to obtain the tunable guided-mode resonance filter. In the invention, the upper transparent conducting film ITO layer and the lower transparent conducting film ITO layer formed by the PDLC layer are applied with voltage to drive the PDLC material; the ITO layer is taken as an electrode layer for applying an electric field to the PDLC and a waveguide layer of the guided-mode resonance filter; refractive index of the PDLC material is used for tuning wavelength; and the filter is tuned by external voltage. The tunable narrow-band pass filter has simple structure, high peak reflectivity and high narrow-band optical spectrum.

Description

A Tunable Narrow Bandpass Filter Based on Polymer Dispersed Liquid Crystal Material technical field The invention is an optical filter device, specifically relates to a tunable narrow-band filter utilizing the electrically controlled folding properties of polymer-dispersed liquid crystal materials, and is used in the fields of optical instruments, optical detection, optical measurement, and biomedicine. There are application prospects. Background technique Tunable systems play an important role in many optical systems and widely exist in the fields of optical instruments, optical detection, optical information processing, optical measurement and biomedicine. Tunable systems usually include three types of filter systems: acousto-optic tuning, electro-optic tuning, and mechanical tuning. The mechanical adjustment method is to achieve the purpose of tuning the spectral characteristics of the filter system by changing the physical parameters of the devices in the system, such...

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Problems solved by technology

The mechanical adjustment method is to achieve the purpose of tuning the spectral characteristics of the filter system by changing the physical parameters of the devices in the system, such as thickness and angle, etc. The main disadvantage is that the tuning response speed is slow and the structure is complicated

Acousto-optic adjustment is a tunable system made by using the abnormal Bragg diffraction effect of anisotropic crystals under the acousto-optic interaction. Although it has the characteristics of compact structure and fast tuning response speed, it is expensive and requires high assembly accuracy Insufficient such as small caliber

Using the electro-optic effect of the crystal, the electro-optic adjustment process requires the application of high voltage, which limits its application range.

In the prior art, there is also a filter system based on a wide-spectrum narrow-band tunable filter based on liquid crystal electronically controlled birefringence (see Chinese invention patent "Wide-spectrum narrow-band tunable filter based on liquid crystal electronically controlled birefringence" , patent application number: 200810059070.9), this method combines the liquid crystal cell and the polarizer, and places several polarizers and liquid crystal cells in an optical path to form an adjustable filter, in which the adjustable purpose is achieved by electronically controlling the birefringence of the liquid crystal. It has considerable advantages, but there are still some essential deficiencies, mainly because the bandwidth of the obtained spectrum is wide and has sidebands; when making it, it is necessary to ensure that the polarizer and the optical axis of the wave plate are at an angle of 45°, and the liquid crystal cell is parallel to the optical axis. Difficulty in implementation

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