scholarly journals Optically Tunable and Thermally Erasable Terahertz Intensity Modulators Using Dye-Doped Liquid Crystal Cells with Metasurfaces

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1580
Author(s):  
Yi-Hong Shih ◽  
Harry Miyosi Silalahi ◽  
Ting-I Tsai ◽  
Yi-Chen Chen ◽  
Jou-Yu Su ◽  
...  

A terahertz metasurface that is imbedded into a dye-doped liquid crystal (DDLC) cell is fabricated in this work. After the metasurface-imbedded DDLC cell is irradiated with a linearly polarized pump beam, the irradiated cell is measured with a terahertz spectrometer. The irradiation of the pump beam causes the adsorption of the dye on one of the substrates of the cell, scattering incident terahertz waves and decreasing the transmittances of the terahertz metasurface at all the frequencies of its resonance spectrum. In addition, these transmittances decrease with an increase in the irradiation times of the pump beam. The adsorbed dye molecules are erased from the substrate after the cell is heated by a hot plate. The cell has similar spectra before the irradiation of the pump beam and after the heating of the hot plate. The aforementioned results reveal that the metasurface-imbedded DDLC cell is an optically tunable and thermally erasable terahertz intensity modulator. Therefore, this cell has the potential in developing intensity attenuators for terahertz imaging, frequency isolators for terahertz telecommunication, and spatial light modulators for terahertz information encryption and decryption.

2006 ◽  
Vol 14 (4) ◽  
Author(s):  
N. Bennis ◽  
A. Spadło ◽  
R. Dąbrowski ◽  
E. Martinelli ◽  
G. Galli ◽  
...  

AbstractAsymmetric antiferroelectric liquid crystal displays (AAFLCD) are attractive since they show a very well defined off state and fast switching time. Moreover, they can be driven by a simple biasless DC compensated waveform. The electrooptical response of an AAFLCD allows for new addressing modes, including quasi-static intermediate greyscales maintained without applying a field and passively addressed multiplexed high-frequency displays and spatial light modulators. A new kind of asymmetric cells have been obtained by using fluorinated block copolymer (FBC) alignment, which enhances surface segregation and provides a low energy surface. In this work we combine FBC alignment with antiferroelectric liquid crystal mixtures containing strongly electronegative fluorinated components. Threshold voltages for the antiferroelectric-ferroelectric phase transition as low as 3 volts are observed. We report the time evolution of the shift of the electro-optical response.


2014 ◽  
Vol 22 (2) ◽  
pp. 1636 ◽  
Author(s):  
Zhen-Yu Rong ◽  
Yu-Jing Han ◽  
Shu-Zhen Wang ◽  
Cheng-Shan Guo

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