Dr. C. Kumar N. Patel Profile

Dr. C. Kumar N. Patel

President & Chief Executive Officer at Pranalytica Inc

SPIE Involvement:

Author

Publications (26)

Proceedings Article | 7 October 2019 Open Access

Quantum cascade lasers: 25 years after the first demonstration

C. Kumar Patel, Mariano Troccoli, Rodolfo Barron-Jimenez

Proceedings Volume 11161, 1116102 (2019) https://doi.org/10.1117/12.2538365

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Proceedings Article | 14 May 2018 Paper

Advances in fast tunable laser spectroscopy in the infrared

C. Kumar Patel, Rodolfo Barron-Jimenez, Ilya Dunayevskiy, Mariano Troccoli

Proceedings Volume 10639, 1063920 (2018) https://doi.org/10.1117/12.2306940

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The invention and development of all-electronically tuned quantum cascade lasers has made it possible to obtain spectral information, covering over 1 μm in the long wave infrared region, regarding absorbers in less than fraction of a millisecond. The electronic tuning is achieved through the use of a acousto-optically generated phase grating in a crystal. As described previously, the acousto-optic modulator (AOM) tuned QCL is capable of switching lasing wavelengths in time of the order of 0.5 μs, regardless of the size of the wavelength step. The wavelength tuning is achieved via change in the acoustic wave RF frequency. Thus, a complete spectrum covering < 1 μm tuning (for example from ~8.5 μm to ~ 9.5 μm) can be obtained in less than 20 μs, when the RF frequency is changes in response to an analog drive. For experimental reproducibility of spectra, we have implemented a digital scanning system that permits selection of step size and step speed.

Using the above system, we have carried out a number of studies to explore the usefulness of rapid scanning QCL systems. One study involves spectroscopy of highly absorbing liquids. Almost all liquids absorb very strongly in the long wave infrared region. We have used attenuated total reflection technique to study liquids such as isopropyl alcohol (IPA), ethanol, water, alcoholic beverage such as vodka, gin and scotch and 2,2,2-trifluroethanol. In each case a complete spectrum from ~8.5 μm to ~ 9.5 μm is recorded in a single shot 500 μs scan.

In another study, we have explored transient mixing of gases (R134A HFC introduced into a fast flowing stream of air) in a flow tube where time dependent spectra of mixing gases are obtained in <600 consecutive shots during a 300 ms time span. I will describe both studies in detail.

The fast spectroscopic study of liquids now opens up the potentially exciting area of real time process monitoring in chemical, biological and food and wine industry. The transient flow spectroscopy study clearly indicates that the AOM tuned QCL system will be of immediate use in supersonic flow studies and in the study of combustion and explosion dynamics.

Proceedings Article | 18 May 2017 Presentation + Paper

High performance 40-stage and 15-stage quantum cascade lasers based on two-material active region composition

P. Figueiredo, M. Suttinger, R. Go, A. Todi, Hong Shu, E. Tsvid, C. Kumar Patel, A. Lyakh

Proceedings Volume 10194, 101942L (2017) https://doi.org/10.1117/12.2264704

KEYWORDS: Quantum cascade lasers, Quantum efficiency, Infrared lasers, Infrared radiation, Laser applications, Continuous wave operation, Active optics, Waveguides, Cladding, Transparency

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Proceedings Article | 18 May 2017 Open Access

Advances in Fabry-Perot and tunable quantum cascade lasers

C. Kumar Patel

Proceedings Volume 10194, 101942H (2017) https://doi.org/10.1117/12.2264813

KEYWORDS: Quantum cascade lasers, Infrared radiation, Long wavelength infrared, Atmospheric propagation, Fabry–Perot interferometers, Mid-IR, Electrons, Absorption, Terahertz radiation, Cryogenics

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Proceedings Article | 25 May 2016 Open Access

Single snapshot standoff detection using sub microsecond tuning speed quantum cascade lasers

C. Kumar Patel

Proceedings Volume 9836, 98362E (2016) https://doi.org/10.1117/12.2225040

KEYWORDS: Bragg cells, Quantum cascade lasers, Acoustics, Standoff detection, Semiconductor lasers, Tunable lasers, Long wavelength infrared, Switching, Infrared spectroscopy, Diffraction gratings

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Proceedings Article | 22 May 2015 Open Access

High power quantum cascade lasers for infrared countermeasures, targeting and illumination, beacons and standoff detection of explosives and CWAs

C. Kumar Patel, Arkadiy Lyakh

Proceedings Volume 9467, 946702 (2015) https://doi.org/10.1117/12.2178050

KEYWORDS: Quantum cascade lasers, Bragg cells, Infrared countermeasures, Mid-IR, Long wavelength infrared, Semiconductor lasers, Optical pumping, High power lasers, Explosives

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Proceedings Article | 4 March 2013 Paper

Multiwatt long wavelength quantum cascade lasers based on high strain composition with 70% injection efficiency

Arkadiy Lyakh, Richard Maulini, Alexei Tsekoun, Rowel Go, C. Kumar N. Patel

Proceedings Volume 8640, 864019 (2013) https://doi.org/10.1117/12.2000423

KEYWORDS: Quantum cascade lasers, Electroluminescence, Pulsed laser operation, Long wavelength infrared, Waveguides, Mid-IR, Transparency, Laser damage threshold, Continuous wave operation, Laser development

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Proceedings Article | 24 May 2012 Open Access

QCL as a game changer in MWIR and LWIR military and homeland security applications

C. Kumar Patel, Arkadiy Lyakh, Richard Maulini, Alexei Tsekoun, Boris Tadjikov

Proceedings Volume 8373, 83732E (2012) https://doi.org/10.1117/12.920476

KEYWORDS: Quantum cascade lasers, Mid-IR, Explosives, Long wavelength infrared, Sensors, Laser sources, Laser applications, Standoff detection, Carbon dioxide lasers

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Proceedings Article | 9 May 2012 Paper

Laser photoacoustic sensor for air toxicity measurements

Coorg Prasad, Jie Lei, Wenhui Shi, Guangkun Li, Ilya Dunayevskiy, C. Kumar Patel

Proceedings Volume 8366, 836608 (2012) https://doi.org/10.1117/12.919241

KEYWORDS: Absorption, Quantum cascade lasers, Sensors, Photoacoustic spectroscopy, Interference (communication), Chemical analysis, Calibration, Signal detection, Tunable lasers, Gases

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Proceedings Article | 21 January 2012 Open Access

High power infrared QCLs: advances and applications

C. Kumar Patel

Proceedings Volume 8268, 826802 (2012) https://doi.org/10.1117/12.916654

KEYWORDS: Quantum cascade lasers, Mid-IR, Long wavelength infrared, Explosives, Infrared radiation, Reliability, Laser sources, Laser applications, Standoff detection

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QCLs are becoming the most important sources of laser radiation in the midwave infrared (MWIR) and longwave infrared (LWIR) regions because of their size, weight, power and reliability advantages over other laser sources in the same spectral regions. The availability of multiwatt RT operation QCLs from 3.5 μm to >16 μm with wall plug efficiency of 10% or higher is hastening the replacement of traditional sources such as OPOs and OPSELs in many applications. QCLs can replace CO₂ lasers in many low power applications. Of the two leading groups in improvements in QCL performance, Pranalytica is the commercial organization that has been supplying the highest performance QCLs to various customers for over four year. Using a new QCL design concept, the non-resonant extraction [1], we have achieved CW/RT power of >4.7 W and WPE of >17% in the 4.4 μm - 5.0 μm region. In the LWIR region, we have recently demonstrated QCLs with CW/RT power exceeding 1 W with WPE of nearly 10 % in the 7.0 μm-10.0 μm region. In general, the high power CW/RT operation requires use of TECs to maintain QCLs at appropriate operating temperatures. However, TECs consume additional electrical power, which is not desirable for handheld, battery-operated applications, where system power conversion efficiency is more important than just the QCL chip level power conversion efficiency. In high duty cycle pulsed (quasi-CW) mode, the QCLs can be operated without TECs and have produced nearly the same average power as that available in CW mode with TECs. Multiwatt average powers are obtained even in ambient T>70°C, with true efficiency of electrical power-to-optical power conversion being above 10%. Because of the availability of QCLs with multiwatt power outputs and wavelength range covering a spectral region from ~3.5 μm to >16 μm, the QCLs have found instantaneous acceptance for insertion into multitude of defense and homeland security applications, including laser sources for infrared countermeasures for protecting aircraft from MANPADS, testing of infrared countermeasures, MWIR and LWIR lasers for identify-friend-or-foe (IFF) personnel beacons, infrared target illuminators and designators and tunable QCL applications including in-situ and standoff detection of chemical warfare agents (CWAs) and explosives. The last of these applications addresses a very important and timely need for detection of improvised explosive devices (IEDs) in combat environments like Iraq and Afghanistan.

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Proceedings Article | 26 May 2011 Paper

Integrated multispectral high-power laser platform for the defeat of heat-seeking missiles

Boris Tadjikov, Alexei Tsekoun, Arkadiy Lyakh, Richard Maulini, Rodolfo Barron, C. Kumar Patel

Proceedings Volume 8039, 80390S (2011) https://doi.org/10.1117/12.884262

KEYWORDS: Quantum cascade lasers, Missiles, High power lasers, Reliability, Heatsinks, Defense and security, Laser systems engineering, Mid-IR, Laser applications, Lasers

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Proceedings Article | 13 May 2011 Open Access

Quantum cascade lasers: a game changer for defense and homeland security IR photonics

C. Kumar Patel

Proceedings Volume 8031, 803126 (2011) https://doi.org/10.1117/12.885806

KEYWORDS: Quantum cascade lasers, Mid-IR, Long wavelength infrared, Infrared countermeasures, Explosives, Target designation, Fiber optic illuminators, Infrared radiation, Laser applications

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Proceedings Article | 17 February 2011 Paper

Multi-watt level short wavelength quantum cascade lasers

Arkadiy Lyakh, Richard Maulini, Alexei Tsekoun, Rowel Go, C. Kumar Patel

Proceedings Volume 7953, 79531L (2011) https://doi.org/10.1117/12.872739

KEYWORDS: Quantum cascade lasers, Continuous wave operation, Pulsed laser operation, Laser processing, Atmospheric propagation, Mirrors, Reliability, Molecular beam epitaxy, Laser systems engineering, Geometrical optics

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SPIE Journal Paper | 1 November 2010

Progress in high-performance quantum cascade lasers

Arkadiy Lyakh, Richard Maulini, Alexei Tsekoun, Chandra Kumar Patel

OE, Vol. 49, Issue 11, 111105, (November 2010) https://doi.org/10.1117/12.10.1117/1.3506192

KEYWORDS: Quantum cascade lasers, Continuous wave operation, Waveguides, Aluminum nitride, Mirrors, Antireflective coatings, Reliability, Pulsed laser operation, High power lasers

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Proceedings Article | 26 September 2009 Paper

High power, high efficiency quantum cascade laser systems for directional infrared countermeasures and other defense and security applications

Richard Maulini, Arkadiy Lyakh, Alexei Tsekoun, Rowel Go, Michael Lane, Tyson Macdonald, C. Kumar Patel

Proceedings Volume 7483, 74830D (2009) https://doi.org/10.1117/12.830228

KEYWORDS: Quantum cascade lasers, Diamond, High power lasers, Continuous wave operation, Infrared countermeasures, Aluminum nitride, Mid-IR, Quantum efficiency, Laser systems engineering

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Proceedings Article | 17 September 2009 Paper

Laser based in-situ and standoff detection of chemical warfare agents and explosives

C. Kumar Patel

Proceedings Volume 7484, 748402 (2009) https://doi.org/10.1117/12.835883

KEYWORDS: Absorption, Explosives, Sensors, Quantum cascade lasers, Target detection, Molecules, Carbon dioxide lasers, Environmental sensing, Standoff detection

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Laser based detection of gaseous, liquid and solid residues and trace amounts has been developed ever since lasers were invented. However, the lack of availability of reasonably high power tunable lasers in the spectral regions where the relevant targets can be interrogated as well as appropriate techniques for high sensitivity, high selectivity detection has hampered the practical exploitation of techniques for the detection of targets important for homeland security and defense applications. Furthermore, emphasis has been on selectivity without particular attention being paid to the impact of interfering species on the quality of detection. Having high sensitivity is necessary but not a sufficient condition. High sensitivity assures a high probability of detection of the target species. However, it is only recently that the sensor community has come to recognize that any measure of probability of detection must be associated with a probability of false alarm, if it is to have any value as a measure of performance. This is especially true when one attempts to compare performance characteristics of different sensors based on different physical principles. In this paper, I will provide a methodology for characterizing the performance of sensors utilizing optical absorption measurement techniques. However, the underlying principles are equally application to all other sensors. While most of the current progress in high sensitivity, high selectivity detection of CWAs, TICs and explosives involve identifying and quantifying the target species in-situ, there is an urgent need for standoff detection of explosives from safe distances. I will describe our results on CO2 and quantum cascade laser (QCL) based photoacoustic sensors for the detection of CWAs, TICs and explosives as well the very new results on stand-off detection of explosives at distances up to 150 meters. The latter results are critically important for assuring safety of military personnel in battlefield environment, especially from improvised explosive devices (IEDs), and of civilian personnel from terrorist attacks in metropolitan areas.

Proceedings Article | 29 August 2009 Paper

New midwave infrared laser sources for defense and security needs

Arkadiy Lyakh, Richard Maulini, Rowel Go, Alexei Tsekoun, C. Kumar Patel

Proceedings Volume 7434, 74340I (2009) https://doi.org/10.1117/12.826595

KEYWORDS: Quantum cascade lasers, Structural design, Mid-IR, Laser development, Laser countermeasures, Defense and security, Infrared radiation, Infrared countermeasures, Continuous wave operation

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Proceedings Article | 29 August 2009 Paper

Compact, rapid, and rugged detector of military and improvised explosives based on external grating cavity quantum cascade lasers

Alexei Tsekoun, Ilya Dunayevskiy, Richard Maulini, Rodolfo Barron-Jimenez, Arkadiy Lyakh, C. Kumar Patel

Proceedings Volume 7434, 74340J (2009) https://doi.org/10.1117/12.826623

KEYWORDS: Explosives, Absorption, Sensors, Quantum cascade lasers, Environmental sensing, Explosives detection, Spectroscopy, Infrared spectroscopy, Molecules

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Proceedings Article | 7 May 2009 Paper

High power and efficiency quantum cascade laser systems for defense and security applications

A. Tsekoun, A. Lyakh, R. Maulini, M. Lane, T. Macdonald, R. Go, C. Kumar Patel

Proceedings Volume 7325, 73250L (2009) https://doi.org/10.1117/12.820236

KEYWORDS: Quantum cascade lasers, Laser systems engineering, Defense and security, Packaging, Fiber optic illuminators, Reliability, High power lasers, Quantum efficiency, Collimation, Defense systems

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Proceedings Article | 29 January 2008 Paper

Intracavity amplitude modulation of quantum-cascade lasers using intersubband absorption in the active region under reverse bias

Arkadiy Lyakh, Richard Maulini, Alexei Tsekoun, Rowel Go, C. Kumar Patel

Proceedings Volume 6909, 690910 (2008) https://doi.org/10.1117/12.767838

KEYWORDS: Absorption, Modulation, Quantum cascade lasers, High dynamic range imaging, Waveguides, Modulators, Amplitude modulation, Laser energy, Resistance, Laser spectroscopy

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Proceedings Article | 28 February 2006 Open Access

High power lasers: achievements, challenges, and opportunities

C. Kumar Patel

Proceedings Volume 6127, 612701 (2006) https://doi.org/10.1117/12.666667

KEYWORDS: Gas lasers, Quantum cascade lasers, High power lasers, Carbon monoxide, Continuous wave operation, Semiconductor lasers, Laser applications, Pulsed laser operation, Laser systems engineering

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Proceedings Article | 10 February 2006 Paper

Improved performance of quantum cascade lasers via manufacturable quality epitaxial side down mounting process utilizing aluminum nitride heatsinks

Alexei Tsekoun, Rowel Go, Michael Pushkarsky, Manijeh Razeghi, C. Kumar Patel

Proceedings Volume 6127, 612702 (2006) https://doi.org/10.1117/12.640089

KEYWORDS: Quantum cascade lasers, Heatsinks, Aluminum nitride, Copper, Indium, Mid-IR, Manufacturing, High power lasers, Continuous wave operation

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Proceedings Article | 25 March 2005 Paper

High-sensitivity high-selectivity detection of CWAs and TICs using tunable laser photoacoustic spectroscopy

Michael Pushkarsky, Michael Webber, C. Kumar Patel

Proceedings Volume 5732, (2005) https://doi.org/10.1117/12.582680

KEYWORDS: Sensors, Absorption, Gas lasers, Photoacoustic spectroscopy, Carbon monoxide, Tunable lasers, Gases, Semiconductor lasers, Toxic industrial chemicals

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Proceedings Article | 29 December 2004 Paper

High-sensitivity photoacoustic detection of chemical warfare agents

Michael Pushkarsky, Michael Webber, Tyson MacDonald, C. Kumar Patel

Proceedings Volume 5617, (2004) https://doi.org/10.1117/12.579102

KEYWORDS: Absorption, Gas lasers, Spectroscopy, Photoacoustic spectroscopy, Carbon monoxide, Gases, Sensors, Nerve, Tunable lasers

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Proceedings Article | 29 December 2004 Paper

Optical detection of chemical warfare agents and toxic industrial chemicals

Michael Webber, Michael Pushkarsky, C. Kumar Patel

Proceedings Volume 5617, (2004) https://doi.org/10.1117/12.579109

KEYWORDS: Sensors, Absorption, Gas lasers, Carbon monoxide, Toxic industrial chemicals, Sensor performance, Spectroscopy, Computer simulations, Performance modeling

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Proceedings Article | 23 September 2002 Paper

Ultra-sensitive gas detection using diode lasers and resonant photoacoustic spectroscopy

Michael Webber, Michael Pushkarsky, C. Patel

Proceedings Volume 4817, (2002) https://doi.org/10.1117/12.452104

KEYWORDS: Photoacoustic spectroscopy, Fiber amplifiers, Modulation, Absorption, Semiconductor lasers, Sensors, Optical fibers, Optical amplifiers, Spectroscopy, Signal detection

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