A broadband tunable liquid crystal terahertz waveplate based on porous graphene transparent electrodes

Abstract

The invention discloses a bandwidth adjustable liquid crystal terahertz wave plate based on a porous graphene transparent electrode. Sub-wavelength metal wire gratings are arranged on the inner side of a substrate of an incidence surface, porous graphene is arranged on the inner side of a substrate on an exit surface, and the two substrates made of fused quartz are sealed and combined to form a liquid crystal box. Two light-control orientation layers are sandwiched between the metal wire gratings and the porous graphene in the liquid crystal box, liquid crystal materials are sandwiched between the two light-control orientation layers, and the liquid crystal materials are terahertz electronic control large birefringence liquid crystal materials. Parallel orientation of liquid crystals is achieved in the liquid crystal box through the mode of light-control orientation, and a 45-degree included angle is formed between the orientation direction and the direction of the metal wire gratings. According to the bandwidth adjustable liquid crystal terahertz wave plate based on the porous graphene transparent electrode, the electronic control birefringence characteristic of the liquid crystals is used, phase delay of ordinary light and extraordinary light is regulated through voltage to correspond to specific wave plates with different frequencies, and the bandwidth adjustable liquid crystal terahertz wave plate has the advantages of being superwide in frequency band, capable of achieving automatic polarization, high in transmittance, large in modulation amount, rapid in response and the like and can be widely applied in the booming terahertz field.

Description

technical field [0001] The invention relates to the technical field of terahertz optoelectronics, in particular to the design and preparation of a broadband tunable terahertz waveplate based on porous graphene terahertz transparent electrodes, subwavelength metal wire grid integrated electrodes / polarizers and liquid crystal materials. Background technique [0002] Liquid crystal materials have both the fluidity of liquids and the orderliness of crystals. Due to their excellent tuning characteristics of external fields (electric field, magnetic field, light field, sound field, temperature field, etc.), they play an important role in information display and adjustable photonic devices. Applications. Nematic liquid crystal is the most commonly used phase state, and in all nematic liquid crystal applications, orientation is the first step. The traditional orientation method, rubbing orientation, is the most widely used method, which has defects such as mechanical damage to the ...

AI Technical Summary

Problems solved by technology

However, when applied to the terahertz frequency band, on the one hand, the commonly used transparent conductive film indium tin oxide will no longer be applicable, and a simple metal layer cannot meet the requirements, so it is necessary to seek new electrode designs such as graphene electrodes to replace traditional films.

On the other hand, the birefringence of most liquid crystal materials will be relatively small in the terahertz frequency band, so the adjustable amount is also small, and it is difficult to meet practical requirements in general design

And some special means to increase the amount of modulation, such as stacked structures, etc., will seriously increase the loss under the condition of lack of transparent electrodes.

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