A15A-T003 (Army)
Intracavity Nonlinear Optical Generation of THz Radiation
Dec 14, 2014
https://www.dodsbir.net/sitis/display_topic.asp?Bookmark=45923
Current sub-THz sources
utilize Schottky-diode based multipliers for the state-of-the-art performance
[1]. On the high frequency side of the “THz gap”, quantum cascade lasers have
shown promise; however, only nonlinear optical approaches show promise for RT
(room temperature), monolithic multi-mW continuous wave (CW) power levels in
the 1-4 THz regime [2-5]. Nonlinear optical generation of 1-6 THz frequency
radiation has been achieved through a number of approaches using various
materials; however, the efficiency of the nonlinear conversion falls-off in
what is known as the “THz gap” around 1 THz. Intracavity generation of THz
radiation indicates the possibility of obtaining relatively high power at
room temperatures from a monolithic package. Applications of such high power
sources to THz spectroscopy [6] and imaging [7] are of interest and hold
unexplored potential. Studies of these application fields at high power
levels has been limited by the availability of the high power sources. The
development of the sources will aid further research of THz techniques and
their applications by making them available to leading THz laboratories.
Thus, the development of such sources for use and distribution to the leading
spectroscopy labs will be part of the commercialization goals in phase II and
III. The efficiency, compactness, and high power output are the main
considerations with an eye toward manufacturability of a significant number
of the sources for use in various THz spectroscopy and imaging laboratories.
Although intracavity nonlinear optical generation of THz radiation is the
primary approach sought to achieve this goal, alternative approaches will be
considered if the monolithic integration of that technology has promise as a
next generation technology.
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PHASE I: Using a proposed
monolithic design, show evidence of feasibility of all major elements.
Develop theoretical estimates with some experimental demonstration of THz
signal generation in the proposed materials. Theoretical estimates should
indicate the feasibility of 10 mW, CW RT at 4 THz and approximate mW power
levels at 1 THz (also CW RT).
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PHASE II: Fabrication and
testing of the full monolithic THz source. Optimization of the laser sources
and frequency conversion designs should be studied, implemented and tested.
The general goals are to demonstrate mWs of power across the 1-4 THz spectrum
(CW, RT), and 50 mW of power by the end of the program across at least a
portion of the 1-4 THz spectrum.
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PHASE III DUAL USE
APPLICATIONS: Terahertz sources have potential uses in both DoD and civilian
applications. Monolithically integrated, efficient RT CW radiation in the 1-4
THz regime will be useful for studies of spectroscopic sensing of various
chemicals. Imaging in this regime will also be of interest with investment in
beam quality which can be further explored with additional Phase III funding.
Transition of the high power sources to various laboratories will be sought
(DoD, NIST, DoE, universities, etc.) to study potential applications. Dual
use applications may include various types of imaging and sensing of unknown
and hidden objects, chemicals, and various biomolecules, as well as remote
sensing applications in meteorology and climatology.
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1. See www.vadiodes.com, for Virginia Diodes,
Inc. 2. M.A. Belkin, F. Capasso, A. Belyanin, D.L. Sivco, A.Y. Cho, D.C.
Oakley, C.J. Vineis, and G.W. Turner Nature Photon. 1, 288 (2007). 3. M. A.
Belkin, F. Capasso, F. Xie, A. Belyanin, M. Fischer, A. Wittmann, and J. Faist,
Appl. Phys. Lett. 92, 201101 (2008). 4. K. Vijayraghavan, R.W. Adams, A.
Vizbaras, M. Jang, C. Grasse, G. Boehm, M. C. Amann, and M.A. Belkin, Appl.
Phys. Lett. 100, 251104 (2012). 5. K. Vijayraghavan, R.W. Adams, A. Vizbaras,
M. Jang, C. Grasse, G. Boehm, M. C. Amann, and M.A. Belkin, Nature Comm. 4,
2021 (2013). 6. P. H. Siegel, “THz Technology,” IEEE Trans. Microwave Theory
and Techniques 50th Anniversary Issue, vol. 50, no. 3, pp. 910-928, March
2002. 7. K. B. Cooper, R. J. Dengler, N. Llombart, A. Talukder, A. V.
Panangadan, C. S. Peay, I. Mehdi, P. H. Siegel, “Fast, high-resolution
terahertz radar imaging at 25 meters,” Proc. SPIE v. 7671, 2010.
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