Article
Chemistry, Multidisciplinary
Janusz Mikolajczyk, Dariusz Szabra
Summary: This paper presents an infrared pulsed modulator that integrates quantum cascade lasers and a current driver. Through simulation and experimental research, it was found that the design of quantum cascade lasers strongly affects the shape of light, driving current, and biasing voltage pulses.
APPLIED SCIENCES-BASEL
(2021)
Article
Optics
Barbara Schneider, Filippos Kapsalidis, Mathieu Bertrand, Matthew Singleton, Johannes Hillbrand, Mattias Beck, Jerome Faist
Summary: This work demonstrates the control of the emitted state from quantum cascade laser frequency combs through strong radio-frequency current modulation, achieving adjustments in spectral bandwidth and center frequency. Different spectral characteristics can be achieved at different modulation frequencies, allowing for the generation of multiple spectral regions on the same device.
LASER & PHOTONICS REVIEWS
(2021)
Article
Pharmacology & Pharmacy
Vladimir Villanueva-Lopez, Leonardo C. Pacheco-Londono, Reynaldo Villarreal-Gonzalez, John R. Castro-Suarez, Andres Roman-Ospino, William Ortiz-Rivera, Nataly J. Galan-Freyle, Samuel P. Hernandez-Rivera
Summary: The PAT initiative proposed by the FDA offers innovative methods for understanding pharmaceutical processes. This study demonstrated the accuracy and robustness of using MIR quantum cascade laser spectroscopy for analysis of pharmaceutical compounds.
Article
Optics
Yanjiao Guan, Ruixuan Sun, Ning Zhuo, Xiyu Lu, Jinchuan Zhang, Shenqiang Zhai, Junqi Liu, Shuman Liu, Lijun Wang, Fengqi Liu
Summary: We have successfully designed and fabricated a dual-wavelength switchable quantum cascade laser (QCL) by optimizing the design of a homogeneous active region and combining superposed distributed feedback gratings. Coaxial, single-mode emissions at two different wavelengths were achieved only through adjusting the bias voltage. The dual-wavelength QCL operates at room temperature and provides output powers of above 30 mW and 75 mW for single-mode emission at 7.61 μm and 7.06 μm, respectively. The simplified fabrication process and easy wavelength control make our designed dual-wavelength QCL very attractive for developing miniature multi-species gas sensing systems.
CHINESE OPTICS LETTERS
(2023)
Article
Chemistry, Analytical
Alicja Dabrowska, Mauro David, Stephan Freitag, Aaron Maxwell Andrews, Gottfried Strasser, Borislav Hinkov, Andreas Schwaighofer, Bernhard Lendl
Summary: Mid-infrared chemical sensors based on quantum cascade technology were developed for broadband detection of aqueous samples targeting bovine milk proteins. The setup combined a tunable quantum cascade laser with a spectrally tailored in-house fabricated quantum cascade detector, showing similar performance to a high-end FTIR spectrometer. The study highlights the potential of quantum cascade detectors in next-generation MIR liquid-phase chemical sensors with low noise and high dynamic range.
SENSORS AND ACTUATORS B-CHEMICAL
(2022)
Article
Environmental Sciences
Mark C. Phillips, Bruce E. Bernacki, Patrick T. Conry, Michael J. Brown
Summary: Chemical plume detection and modeling in complex terrain pose challenges. The study conducted outdoor experiments using two tracers to release chemical plumes in mountainous terrain. The results showed that plume propagation dynamics near the release points were highly variable and dependent on local topography and winds. The study highlights the importance of high-speed and spatially resolved measurement techniques for validating terrain-aware microscale plume propagation models.
Article
Multidisciplinary Sciences
Song Han, Yunda Chua, Yongquan Zeng, Bofeng Zhu, Chongwu Wang, Bo Qiang, Yuhao Jin, Qian Wang, Lianhe Li, Alexander Giles Davies, Edmund Harold Linfield, Yidong Chong, Baile Zhang, Qi Jie Wang
Summary: In this study, an electrically pumped topological laser based on photonic Majorana zero mode is implemented on a quantum cascade chip. The laser emits a topologically nontrivial cylindrical vector beam from a terahertz semiconductor laser. This electrically driven topological laser represents an important breakthrough for converting electricity into THz single-mode laser with nontrivial beams.
NATURE COMMUNICATIONS
(2023)
Article
Optics
Enhao Li, Hiyori Uehara, Shigeki Tokita, Weichao Yao, Ryo Yasuhara
Summary: A hybrid continuous-wave Fe:ZnSe laser amplifier, seeded with a mid-infrared quantum cascade laser, achieved high output power and extraction efficiency. Theoretical analysis provided possible routes for further optimization of this system.
OPTICS AND LASER TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Xiaodan Pang, Richard Schatz, Mahdieh Joharifar, Aleksejs Udalcovs, Vjaceslavs Bobrovs, Lu Zhang, Xianbin Yu, Yan-Ting Sun, Gregory Maisons, Mathieu Carras, Sergei Popov, Sebastian Lourdudoss, Oskars Ozolins
Summary: A roadmap for future wireless communications is aiming to utilize all transmission-suitable spectrum bands, including the under-exploited mid-infrared (mid-IR) spectrum. This spectrum has gained interest in free-space optical (FSO) communications due to its low propagation loss and high tolerance of atmospheric perturbations. A quantum cascade laser (QCL) is considered a promising technological choice for viable mid-IR FSO transceivers, as it fulfills the requirements of high bandwidth, low energy consumption, and small footprint.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Optics
Arman Amirzhan, Paul Chevalier, Jeremy Rowlette, H. Ted Stinson, Michael Pushkarsky, Timothy Day, Henry O. Everitt, Federico Capasso
Summary: By utilizing methyl fluoride as a new gain medium, the study demonstrates continuous-wave lasing from more than 120 discrete transitions spanning the range from 0.25 to 1.3 THz, offering lower threshold, higher power efficiency, and wider tuning range compared to other molecules.
Article
Optics
Yanjiao Guan, Lijun Wang, Ning Zhuo, Jinchuan Zhang, Shenqiang Zhai, Junqi Liu, Shuman Liu, Fengqi Liu
Summary: The dual-wavelength quantum cascade laser achieves single-mode emission at 7.6 μm and 8.2 μm through a heterogeneous active region within a single waveguide, with high optical powers obtained for both wavelengths. This design concept is significant in developing miniaturized multi-species gas detection systems.
Article
Chemistry, Multidisciplinary
Frank Herklotz, Tom Rubin, Malte Sinnreich, Alexander Helmke, Theodore von Haimberger, Karsten Heyne
Summary: This study presents a sensing technique using quantum cascade lasers for high-precision temperature and/or CO2 concentration measurements in gases at room temperature. By recording absorption spectra of CO2 transitions, the method achieves high measurement accuracy and sampling rates.
APPLIED SCIENCES-BASEL
(2022)
Article
Chemistry, Multidisciplinary
Wenjia Zhou, Rui Xu, Haobo Wu, Xianyuan Jiang, Hao Wang, F. Pelayo Garcia de Arquer, Zhijun Ning
Summary: In this study, we developed a QD monolithic multijunction cascade photodetector with high gain and high response speed by controlling the bandgap and electrostatic surface of QDs. The detector achieved high sensitivity to infrared light up to 1500 nm wavelength, with a specific detectivity of 3.7 x 10^12 Jones, a 3 dB bandwidth of 300 kHz (0.05 cm^2 device), and a gain of approximately 70x at 1300 nm. Compared to standard photodiode devices, the QD photodetector exhibited a significantly higher gain-bandwidth product over 20 MHz.
Article
Optics
Philipp Taschler, Lucius Miller, Filippos Kapsalidis, Mattias Beck, Jerome Faist
Summary: By leveraging the picosecond carrier dynamics observed in quantum cascade lasers (QCLs), we have successfully generated 33 ps optical pulses with watt-level peak power using short electrical excitations. Optical injection seeding ensured lasing on a single resonator mode, and the resulting pulses were characterized in both time and frequency domains. These results open new pathways for the generation of highly tunable, high power mid-infrared pulses from a monolithic source.
Article
Nanoscience & Nanotechnology
Michael Jaidl, Maximilian Beiser, Miriam Giparakis, Martin Alexander Kainz, Dominik Theiner, Benedikt Limbacher, Marie Christine Ertl, Aaron Maxwell Andrews, Gottfried Strasser, Juraj Darmo, Karl Unterrainer
Summary: This study presents a heterogeneous terahertz quantum cascade laser consisting of five individual active regions based on a three-well, LO-phonon depopulation design. The lasers can operate in both pulsed and continuous-wave modes, emitting in a spectral range from 1.9 to 4.5 THz, with broad bandwidth.
Article
Chemistry, Analytical
Yamuna Phal, Kevin Yeh, Rohit Bhargava
Summary: Vibrational circular dichroism (VCD) spectroscopy is a powerful tool for quantifying chirality in biological organisms. By integrating a photoelastic modulator (PEM) into an infrared spectrometer, it is possible to deduce conformation handedness from a sample's differential response to circularly polarized light. Advancements in discrete frequency infrared (DFIR) spectroscopic microscopes show promise for improving the quality and data throughput of analytical VCD measurements.
ANALYTICAL CHEMISTRY
(2021)
Article
Multidisciplinary Sciences
Saumya Tiwari, Andre Kajdacsy-Balla, Joshua Whiteley, Georgina Cheng, Stephen M. Hewitt, Rohit Bhargava
Summary: This study introduces a measurement framework based on high-definition infrared imaging that uses the intrinsic chemical contrast of tissue to label unique components of tumors and their microenvironments, predicting overall survival in colon cancer patients. The results reveal the association between tumor spatial organization and disease progression.
Review
Instruments & Instrumentation
Yamuna Phal, Kevin Yeh, Rohit Bhargava
APPLIED SPECTROSCOPY
(2021)
Article
Instruments & Instrumentation
Laurin Lux, Yamuna Phal, Pei-Hsuan Hsieh, Rohit Bhargava
Summary: The performance of infrared spectroscopic imaging instruments can be characterized and optimized by analyzing their limit of detection (LOD). In this study, a systematic analysis of LOD for Fourier transform IR (FT-IR) and discrete frequency IR (DFIR) imaging spectrometers was conducted, with a decision theory perspective and three spectral analysis approaches. The analysis validated the impact of different spectral analysis methods on LOD under typical imaging parameters for each instrument, and emphasized the possibility of improvement through usual trading rules of IR spectroscopy.
APPLIED SPECTROSCOPY
(2022)
Article
Medicine, Research & Experimental
Kianoush Falahkheirkhah, Tao Guo, Michael Hwang, Pheroze Tamboli, Christopher G. Wood, Jose A. Karam, Kanishka Sircar, Rohit Bhargava
Summary: The study synthesized virtual formalin-fixed paraffin-embedded (FFPE)-like images from frozen (FF) section samples using a generative adversarial network (GAN), showing high image quality and increased inter-observer agreement in clinical assessments compared to real FF images. This approach can potentially improve the speed and accuracy of histopathologic examinations without additional costs or efforts.
LABORATORY INVESTIGATION
(2022)
Article
Instruments & Instrumentation
Saumya Tiwari, Kianoush Falahkheirkhah, Georgina Cheng, Rohit Bhargava
Summary: This study aims to assess the tumor grade of colorectal cancer using FT-IR imaging. A deep learning classifier was developed to estimate the tumor grade based on IR absorption, and the effectiveness of this method was validated on an independent cohort. The study demonstrates that combining molecular information from FT-IR imaging with morphometry could lead to the development of clinically relevant grade prediction models.
APPLIED SPECTROSCOPY
(2022)
Article
Instruments & Instrumentation
Shachi Mittal, Jonathan Kim, Rohit Bhargava
Summary: Advancements in infrared spectroscopic imaging and data science offer unique opportunities for histopathology validation studies. This study examines the discrimination potential of infrared metrics for different histologic classes and introduces an automated annotation transfer tool for large-scale training/validation. Results from supervised and unsupervised analysis provide insights for identifying diagnostic groups/patterns and improving training of histopathological models.
APPLIED SPECTROSCOPY
(2022)
Article
Chemistry, Physical
Yamuna Phal, Luke Pfister, P. Scott Carney, Rohit Bhargava
Summary: This study uses an information theory-based approach to quantify the spatial localization capability of spectral data in chemical imaging. The study explicitly considers the influence of signal-to-noise ratio and spectral separation on the resolution limits of IR spectroscopic imaging.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Analytical
Pei-Hsuan Hsieh, Yamuna Phal, Kannanganattu Prasanth, Rohit Bhargava
Summary: Cell cycle progression is crucial for regulating cell proliferation, metabolism, and apoptosis. Fourier transform infrared spectroscopic imaging is used to identify biochemical changes in cells that indicate the different phases of the cell cycle. This study presents a computational and quantitative approach to analyze cell phases in tissue-like 3D structures without the need for biomarker staining, providing insights into the impact of cell cycle on 3D biological systems and disease diagnostic studies.
ANALYTICAL CHEMISTRY
(2022)
Article
Medicine, Research & Experimental
Kianoush Falahkheirkhah, Saumya Tiwari, Kevin Yeh, Sounak Gupta, Loren Herrera-Hernandez, Michael R. McCarthy, Rafael E. Jimenez, John C. Cheville, Rohit Bhargava
Summary: A pathologist's examination of tissue on glass slides is the gold standard for tissue diagnostics, but obtaining expert-level annotated images is expensive. This study presents a generative adversarial network model that synthesizes pathology images, which performed similarly to real data. Furthermore, the ability for a user to generate deepfake histologic images using a simple markup of sematic labels is demonstrated.
LABORATORY INVESTIGATION
(2023)
Article
Multidisciplinary Sciences
Seth Kenkel, Mark Gryka, Lin Chen, Matthew P. Confer, Anirudha Rao, Scott Robinson, Kannanganattu V. Prasanth, Rohit Bhargava
Summary: Nearfield spectroscopic imaging techniques can be a powerful tool to simultaneously map cellular ultrastructure and molecular composition, but their current capabilities are limited. This study proposes an instrument design that combines null-deflection measurements with resonance enhancement to achieve high-sensitivity nanoscale infrared imaging. Experimental results using cellular acini samples demonstrate the ability of this method to easily record high-quality chemical imaging data.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Chemistry, Multidisciplinary
Jian Wang, Necip B. Uner, Scott Edwin Dubowsky, Matthew P. Confer, Rohit Bhargava, Yunyan Sun, Yuting Zhou, R. Mohan Sankaran, Jeffrey S. Moore
Summary: The formation of carbon-carbon bonds by pinacol coupling of aldehydes and ketones can be achieved using solvated electrons generated via a plasma-liquid process. Selectivity over the competing reduction to the alcohol requires careful control over mass transport. The generality of this method is demonstrated with various substrates, and a reaction-diffusion model and ab initio calculations provide insights into the mechanism. This study opens the possibility of a metal-free, electrically-powered, sustainable method for reductive organic reactions.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Analytical
Sudipta S. Mukherjee, Rohit Bhargava
Summary: Infrared (IR) spectroscopic imaging provides spatially resolved molecular absorption spectra, and this study introduces a fast and reliable method based on a phasor representation of spectra. The method is applicable for rapid data exploration and analysis of IR imaging data, and shows potential in biomedical tissue imaging.
ANALYTICAL CHEMISTRY
(2023)
Article
Multidisciplinary Sciences
Kevin Yeh, Ishaan Sharma, Kianoush Falahkheirkhah, Matthew P. Confer, Andres C. Orr, Yen-Ting Liu, Yamuna Phal, Ruo-Jing Ho, Manu Mehta, Ankita Bhargava, Wenyan Mei, Georgina Cheng, John C. Cheville, Rohit Bhargava
Summary: Chemical imaging, especially mid-infrared spectroscopic microscopy, allows label-free biomedical analysis with high molecular sensitivity. However, its slow speed and poor image quality hinder its widespread adoption. A new microscope design overcomes these limitations by providing high-throughput recording, low noise, and high spatial resolution, enabling speckle-free, high-resolution imaging at theoretical limits.
NATURE COMMUNICATIONS
(2023)