Abstract-Antireflection self-reference method based on ultrathin metallic nanofilms for improving terahertz reflection spectroscopy

Weien Lai, Haibing Cao, Jun Yang, Guangsheng Deng, Zhiping Yin, Qian Zhang, Beatriz Pelaz, and Pablo del Pino

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-15-19470

We present the potential of an antireflection self-reference method based on ultra-thin tantalum nitride (TaN) nanofilms for improving terahertz (THz) reflection spectroscopy. The antireflection self-reference method is proposed to eliminate mutual interference caused by unwanted reflections, which significantly interferes with the important reflection from the actual sample in THz reflection measurement. The antireflection self-reference model was investigated using a wave-impedance matching approach, and the theoretical model was verified in experimental studies. We experimentally demonstrated this antireflection self-reference method can completely eliminate the effect of mutual interference, accurately recover the actual sample’s reflection and improve THz reflection spectroscopy. Our method paves the way to implement a straightforward, accurate and efficient approach to investigate THz properties of the liquids and biological samples.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Enhanced All-Optical Modulation of Terahertz Waves Based on Manganese Ferrite Nanoparticles

Weien Lai, Peng Huang, Beatriz Pelaz, Pablo del Pino, and Qian Zhang

http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.7b07756?mi=aayia761&af=R&AllField=nano&target=default&targetTab=std

We present an all-optical modulator based on manganese ferrite nanoparticles (MnFe2O4 NPs), which provides an enhanced attenuation of broadband terahertz waves. A wide-band modulation of THz transmission was observed in a frequency range from 0.15 to 1.2 THz. The experimental results were assessed by simulations in the context of a band structure model of semiconductors. Our work demonstrated that coatings of MnFe2O4 NPs can be efficiently used to improve the performance of THz modulators based on optical modulation. This paper describes a new route to increase the surface photoconductivity of semiconductors by coating of MnFe2O4 NPs. This work demonstrates that the THz modulator based on MnFe2O4 NPs can significantly boost the overall performance of THz communication systems, and MnFe2O4 NPs may offer some useful solutions for future THz devices

Abstract-Enhanced Terahertz Radiation Generation of Photoconductive Antennas Based on Manganese Ferrite Nanoparticles

• Weien Lai
• , Oday Mazin Abdulmunem
• , Pablo del Pino
• , Beatriz Pelaz
• , Wolfgang J. Parak
• , Qian Zhang
•  & Huaiwu Zhang
• • 
    
  • http://www.nature.com/articles/srep46261

This paper presents a significant effect of manganese ferrite nanoparticles (MnFe2O4 NPs) on the increase of the surface photoconductivity of semiconductors. Herein, the optical characterization of photo-excited carriers of silicon coated with MnFe2O4 NPs was studied by using THz time-domain spectroscopy (THz-TDs). We observed that silicon coated with MnFe2O4 NPs provided a significantly enhanced attenuation of THz radiation in comparison with bare silicon substrates under laser irradiation. The experimental results were assessed in the context of a surface band structure model of semiconductors. In addition, photoconductive antennas coated with MnFe2O4 NPs significantly improved the efficiency of THz radiation generation and signal to noise ratio of the THz signal. This work demonstrates that coating with MnFe2O4 NPs could improve the overall performance of THz systems, and MnFe2O4 NPs could be further used for the implementation of novel optical devices.

Abstract-Frequency-Dependent Dual-Functional Coding Metasurfaces at Terahertz Frequencies

http://onlinelibrary.wiley.com/doi/10.1002/adom.201600471/full

A frequency-dependent dual-functional coding metasurface is proposed at terahertz frequencies using two layers of metamaterial structures, each of which is responsible for the independent control of reflection phases at two distinct frequencies. The zero interference between the functionalities at the lower and higher frequencies are promising for possible applications in multicolor holography for color displays or a frequency beam splitter.