Abstract-THz absorption spectrum employed for characterize the mixed Gallium selenide-Tin disulfide saturable absorber and its application for passively Q-switched solid state laser

Qi Song, Bingyuan Zhang, Guoju Wang


https://www.sciencedirect.com/science/article/pii/S135044951830433X

Due to the ultra-short recovery time and the wider absorption range, graphene-like 2D material have been widely employed as saturable absorbers (SAs) in passively Q-switched and mode-locked lasers. Due to the low photon energy, noninvasive and high resolution, THz wave was widely used to characterize samples. In this paper, the nonlinear saturable absorption property and THz absorption spectrum of Gallium selenide/Tin disulfide (GaSe/SnS2) is reported. Passively Q-switched Nd:GdTaO4 laser with GaSe/SnS2 SA is demonstrated. The maximum output power of 551 mW under the pump power of 5 W. The minimum pulse width is 365 ns at the pulse repetition rate of 89 kHz. Our results indicate that GaSe/SnS2 nanosheets could be used in Q-switched lasers. The GaSe/SnS2 SA with good nonlinear absorption properties and easy fabricating process will promote the ultrafast photonics applications in solid state lasers

Abstract- A simulation study on terahertz absorption of liquid crystal mixture E7

Jian-qi Dong, Wen-qi Cheng, Meng-ge Li, Kai-li Wang, Ze-zhang Chen, Heng Ma,

http://iopscience.iop.org/article/10.1088/1361-6463/aa7d6c/meta

A simulation work on a broad THz absorption of liquid crystal mixture E7 consisting of 5CB, 7CB, 8OCB and 5CT is reported. Based on the density functional theory, the molecular structures of the monomers were optimized and calculated using the Gaussian package with base set B3LYP and 6-311g. The results indicate that the simulation of the characteristic absorption spectra is accurate compared to the experimental and literature report in the infrared band. By analyzing contribution of the benzene ring, C–O and alkyl bonds on THz absorption, it is found that there are no significant effects from the cyano group and the alkyl radical. The addition of a benzene ring leads to an increase in absorption intensity and redshift. By discussing the atomic mass distribution and the structural symmetry of the monomers, a reason for the strong THz absorption of 8OCB is proposed.

Researchers at North Carolina State University Release New Data on Coenzymes

http://www.hispanicbusiness.com/2013/10/2/researchers_at_north_carolina_state_university.htm
By a News Reporter-Staff News Editor at Life Science Weekly--

Investigators publish new report on Enzymes and Coenzymes. According to news reporting originating from Raleigh, North Carolina, by NewsRx correspondents, research stated, "Terahertz (THz) absorption of biotin was simulated using the first principle and the density functional theory (DFT) both in the harmonic approximation and with corrections for the anharmonicity. Anharmonicity corrections were calculated using two different approaches."
Our news editors obtained a quote from the research from North Carolina State University, "First, the perturbation theory-based first principle calculations were performed to include third-and fourth-order anharmonicity corrections in atomic displacements to harmonic vibrational states. Second, the atom-centered density matrix propagation molecular dynamics model that provides a good energy conservation was used to calculate the atomic trajectories, velocities, and a dipolemoment time history of biotin at lowand room temperatures. Predicted low-THz lines agree well with the experimental spectra. The influence of the polyethylene (PE) matrix embedment on the THz spectra of biotin at the nanoscale was studied using the developed hybrid DFT/molecular mechanical approach."
According to the news editors, the research concluded: "While PE is almost transparent at THz frequencies, additional low-THz lines are predicted in the biotin/PE system, which reflects a dynamic interaction between biotin and a surrounding PE cavity."

For more information on this research see: Terahertz Spectra of Biotin Based on First Principle, Molecular Mechanical, and Hybrid Simulations. IEEE Transactions on Terahertz Science and Technology, 2013;3(4):357-362. IEEE Transactions on Terahertz Science and Technology can be contacted at: Ieee-Inst Electrical Electronics Engineers Inc,445 Hoes Lane, Piscataway, NJ 08855-4141, USA. (Institute of Electrical and Electronics Engineers - www.ieee.org/; IEEE Transactions on Terahertz Science and Technology - ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=5503871)

The news editors report that additional information may be obtained by contacting A. Bykhovski, North Carolina State University, Dept. of Elect & Comp Engn, Raleigh, NC 27695, United States (see also Enzymes and Coenzymes).
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