Abstract-Terahertz hyperspectral imaging with dual chip-scale combs

Lukasz A. Sterczewski, Jonas Westberg, Yang Yang, David Burghoff, John Reno, Qing Hu, Gerard Wysocki

https://arxiv.org/abs/1812.03505

Hyperspectral imaging is a technique that allows for the creation of multi-color images. At terahertz wavelengths, it has emerged as a prominent tool for a number of applications, ranging from non-ionizing cancer diagnosis and pharmaceutical characterization to non-destructive artifact testing. Contemporary terahertz imaging systems typically rely on non-linear optical down-conversion of a fiber-based near-infrared femtosecond laser, requiring complex optical systems. Here, we demonstrate hyperspectral imaging with chip-scale frequency combs based on terahertz quantum cascade lasers. The dual combs are free-running and emit coherent terahertz radiation that covers a bandwidth of 220 GHz at 3.4 THz with ~10 μW per line. The combination of the fast acquisition rate of dual-comb spectroscopy with the monolithic design, scalability, and chip-scale size of the combs is highly appealing for future imaging applications in biomedicine and in the pharmaceutical industry

Abstract-Terahertz dual-comb spectroscopy using quantum cascade laser frequency combs

Jonas Westberg, Lukasz A. Sterczewski, Yang Yang, David Burghoff, John Reno, Qing Hu,  Gerard Wysocki,

http://www.etoponline.org/abstract.cfm?uri=CLEO_SI-2018-STu4D.2dua

We demonstrate THz dual comb spectroscopy of molecular samples using dispersion compensated quantum cascade lasers. The system achieves an optical bandwidth of ~150 GHz at 2.9 THz and is used to measure ammonia in gas phase.

© 2018 The Author(s)

Abstract-Passively mode-locked interband cascade optical frequency combs

Mahmood Bagheri, Clifford Frez, Lukasz A. Sterczewski, Ivan Gruidin, Mathieu Fradet, Igor Vurgaftman, Chadwick L. Canedy, William W. Bewley, Charles D. Merritt, Chul Soo Kim, Mijin Kim,  Jerry R. Meyer

https://www.nature.com/articles/s41598-018-21504-9

Since their inception, optical frequency combs have transformed a broad range of technical and scientific disciplines, spanning time keeping to navigation. Recently, dual comb spectroscopy has emerged as an attractive alternative to traditional Fourier transform spectroscopy, since it offers higher measurement sensitivity in a fraction of the time. Midwave infrared (mid-IR) frequency combs are especially promising as an effective means for probing the strong fundamental absorption lines of numerous chemical and biological agents. Mid-IR combs have been realized via frequency down-conversion of a near-IR comb, by optical pumping of a micro-resonator, and beyond 7 μm by four-wave mixing in a quantum cascade laser. In this work, we demonstrate an electrically-driven frequency comb source that spans more than 1 THz of bandwidth centered near 3.6 μm. This is achieved by passively mode-locking an interband cascade laser (ICL) with gain and saturable absorber sections monolithically integrated on the same chip. The new source will significantly enhance the capabilities of mid-IR multi-heterodyne frequency comb spectroscopy systems.

Abstract-Piroxicam derivatives THz classification

Lukasz A. Sterczewski, Michal P. Grzelczak, Kacper Nowak, Boguslaw Szlachetko,Edward F. Plinski

Wroclaw Univ. of Technology (Poland)

Stanislawa Plinska, Berenika Szczesniak-Siega, Wieslaw Malinka

Wroclaw Medical Univ. (Poland)

Proc. SPIE 9747, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications IX, 97470Z (February 25, 2016); doi:10.1117/12.2224913

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2498793

In this paper we report a new approach to linking the terahertz spectral shapes of drug candidates having a similar molecular structure to their chemical and physical parameters. We examined 27 newly-synthesized derivatives of a well-known nonsteroidal anti-inflammatory drug Piroxicam used for treatment of inflammatory arthritis and chemoprevention of colon cancer. The testing was carried out by means of terahertz pulsed spectroscopy (TPS). Using chemometric techniques we evaluated their spectral similarity in the terahertz range and attempted to link the position on the principal component analysis (PCA) score map to the similarity of molecular descriptors. A simplified spectral model preserved 75% and 85.1% of the variance in 2 and 3 dimensions respectively, compared to the input 1137. We have found that in 85% of the investigated samples a similarity of the physical and chemical parameters corresponds to a similarity in the terahertz spectra. The effects of data preprocessing on the generated maps are also discussed. The technique presented can support the choice of the most promising drug candidates for clinical trials in pharmacological research. 

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