Abstract-Terahertz response of gadolinium gallium garnet (GGG) and gadolinium scandium gallium garnet (SGGG)

Mohsen Sabbaghi, George W. Hanson, Michael Weinert, Fan Shi, Cheng Cen

https://arxiv.org/abs/2001.05085

We report the magneto-optical response of Gadolinium Gallium Garnet (GGG) and Gadolinium Scandium Gallium Garnet (SGGG) at frequencies ranging from 300GHz to 1THz, and determine the material response tensor. Within this frequency window, the materials exhibit nondispersive and low-loss optical responses. At low temperatures, significant THz Faraday rotations are found in the (S)GGG samples. Such strong gyroelectric response is likely associated with the high-spin paramagnetic state of the Gd3+ ions. A model of the material response tensor is determined, together with the Verdet and magneto-optic constants.

Abstract-Observation of extremely efficient terahertz generation from mid-infrared two-color laser filaments

• Anastasios D. Koulouklidis, 
• Claudia Gollner, 
• Valentina Shumakova, 
• Vladimir Yu. Fedorov, 
• Audrius Pugžlys, 
• Andrius Baltuška,  
• Stelios Tzortzakis, 
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• 
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https://www.nature.com/articles/s41467-019-14206-x

Extreme nonlinear interactions of THz electromagnetic fields with matter are the next frontier in nonlinear optics. However, reaching this frontier in free space is limited by the existing lack of appropriate powerful THz sources. Here, we experimentally demonstrate that two-color filamentation of femtosecond mid-infrared laser pulses at 3.9 μm allows one to generate ultrashort sub-cycle THz pulses with sub-milijoule energy and THz conversion efficiency of 2.36%, resulting in THz field amplitudes above 100 MV cm−1. Our numerical simulations predict that the observed THz yield can be significantly upscaled by further optimizing the experimental setup. Finally, in order to demonstrate the strength of our THz source, we show that the generated THz pulses are powerful enough to induce nonlinear cross-phase modulation in electro-optic crystals. Our work paves the way toward free space extreme nonlinear THz optics using affordable table-top laser systems.

Abstract-Extremely Bright THz Radiation from Two-color Filamentation of Mid-infrared Laser Pulses

Vladimir Yu. Fedorov and Stelios Tzortzakis

https://www.osapublishing.org/abstract.cfm?uri=cleo_qels-2018-JTu2A.113&origin=search

We show numerically that two-color filamentation of mid-infrared 3.9 µm laser pulses allows one to generate THz pulses of multi-millijoule energies and extreme conversion efficiencies, with electric and magnetic fields of GV/cm and kT level, exceeding by far any available quasi-DC field source today.

© 2018 The Author(s)

Abstract-Detection of Harmful Residues in Honey Using Terahertz Time-Domain Spectroscopy

Maria Massaouti, Christina Daskalaki, Andrei Gorodetsky, Anastasios D. Koulouklidis, and Stelios Tzortzakis 

http://www.opticsinfobase.org/as/abstract.cfm?uri=as-67-11-1264

Terahertz time-domain spectroscopy (THz-TDS) has been applied for the detection and discrimination of harmful chemical residues in honey. Three antibiotics (sulfapyridine, sulfathiazole, and tetracycline) and two acaricides (coumaphos and amitraz) were characterized in the THz frequency regime between 0.5 THz and 6.0 THz. All chemical substances present distinct absorption peaks. THz transmission measurements of honey mixtures with antibiotics have been performed, revealing that antibiotic residues are traceable in highly absorptive food products, such as honey, at concentrations down to 1% weight percentage, thanks to their THz fingerprints. Moreover, multiple antibiotics were identified in their mixture with honey, pointing out the potential of the technique to be used in the near future as a fast, real-time technique for detecting and discriminating multi-residues strictly related to food safety issues.