Abstract-The terahertz metamaterials for sensitive biosensors in the detection of ethanol solutions

Author links open overlay panelFuyu Li, Ke He, Tingting Tang, Yinghui Mao, Rui Wang, Chaoyang Li, Jian Shen,

                                               

https://www.sciencedirect.com/science/article/abs/pii/S0030401820307045 

Metamaterials have attracted much attention due to their subwavelength characteristics, especially in the field of unlabeled refractive index sensing. Because biomolecular molecules have special biological fingerprint spectra in terahertz band, high sensitivity sensor components can be realized by using the special electromagnetic response of metamaterials. In this paper, a novel biosensor based on electromagnetic induced reflection is designed. We find that the asymmetrically fractured double-ring resonator can effectively enhance the fano-resonance of electromagnetic induction reflection, where the resonance position occurs at 1.57 THz. Oscillating Lorentz model shows that when the resonant detuning continues to increase, the bright mode and the dark mode are strongly coupled. When the light mode decreases, the radiation loss also decreases, which induces the decrease of resonance ability. The sensitivity of pure ethanol solution (analyte) under  coating thickness is 103.7 GHz/RIU, 107.1 GHz/RIU and 112.05 GHz/RIU, respectively. The sensitivity and full width at half maximum (FWHM) of the sensor are studied from the perspectives of analyte concentration, thickness, and proportion, respectively. The results show the great potential of electromagnetic metamaterials as sensitive sensors in biological solution detection.

Abstract-Tunable lifetime multiplexing using luminescent nanocrystals

• • Lifetime tuning scheme and time-resolved confocal images for NaYF4:Yb,Tm upconversion nanocrystals.
• Yiqing Lu,
• Jiangbo Zhao,
• Run Zhang,
• Yujia Liu,
• Deming Liu,
• Ewa M. Goldys,
• Xusan Yang,
• Peng Xi,
• Anwar Sunna,
• Jie Lu,
• Yu Shi,
• Robert C. Leif,
• Yujing Huo,
• Jian Shen,
• James A. Piper,
• J. Paul Robinson
• & Dayong Jin

http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2013.322.html
Optical multiplexing plays an important role in applications such as optical data storage¹, document security², molecular probes^3, 4 and bead assays for personalized medicine⁵. Conventional fluorescent colour coding is limited by spectral overlap and background interference, restricting the number of distinguishable identities. Here, we show that tunable luminescent lifetimes τ in the microsecond region can be exploited to code individual upconversion nanocrystals. In a single colour band, one can generate more than ten nanocrystal populations with distinct lifetimes ranging from 25.6 µs to 662.4 µs and decode their well-separated lifetime identities, which are independent of both colour and intensity. Such ‘τ-dots’ potentially suit multichannel bioimaging, high-throughput cytometry quantification, high-density data storage, as well as security codes to combat counterfeiting. This demonstration extends the optical multiplexing capability by adding the temporal dimension of luminescent signals, opening new opportunities in the life sciences, medicine and data security.

Abstract-Damping modulated terahertz emission of ferromagnetic films excited by ultrafast laser pulses

 

http://apl.aip.org/resource/1/applab/v101/i7/p072401_s1?isAuthorized=no

Jian Shen^1,2, Xin Fan², Zhiyuan Chen², Matthew F. DeCamp², Huaiwu Zhang¹, and John Q. Xiao²

¹State Key Laboratory of Electronic Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China 
²Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA 

Ultrafast demagnetization processes in ferromagnetic films have been shown to produce terahertz (THz) emission. We present an experimental demonstration that, following ultrafast optical excitation, the magnitude of terahertz electromagnetic pulses emitted from a ferromagnetic film is proportional to the Gilbert damping constant, which is conventionally used to describe the damping of magnetization precession. The damping of a ferromagnetic thin film is tuned by using an adjacent nonmagnetic layer, which does not change the magnetization and anisotropy of the ferromagnetic film, allowing an unambiguous determination of the relationship between the THz emission and the damping constant.

© 2012 American Institute of Physics