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Principles and promise of Fabry-Perot resonators at terahertz frequencies

Braakman, R. and Blake, G. A. (2011) Principles and promise of Fabry-Perot resonators at terahertz frequencies. Journal of Applied Physics, 109 (6). Art. No. 063102. ISSN 0021-8979.

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Fabry–Perot resonators have tremendous potential to enhance the sensitivity of spectroscopic systems at terahertz (THz) frequencies. Increasing sensitivity will be of benefit in compensating for the relatively low power of current high resolution continuous wave THz radiation techniques, and to fully express the potential of THz spectroscopy as source power increases. Improved sensitivities, and thus scanning speeds, will allow detailed studies of the complex vibration-rotation-tunneling dynamics that large molecules show at THz wavelengths, and will be especially important in studying more elusive, transient species such as those present in planetary atmospheres and the interstellar medium. Coupling radiation into the cavity presents unique challenges at THz frequencies, however, meaning that the cavity configurations common in neighboring frequency domains cannot simply be translated. Instead, novel constructions are needed. Here we present a resonator design in which wire-grid polarizers serve as the input and output coupling mirrors. Using this configuration, Q-factors of a few times 10^5 are achieved near 0.3 THz. To aid future investigations, the parameter space that limits the quality of the cavity is explored and paths to improved performance highlighted. Lastly, the performance of polarizer cavity-based Fourier transform (FT) THz spectrometers is discussed, in particular those design optimizations that should allow for the construction of THz instrumentation that rivals and eventually surpasses the sensitivities achieved with modern FT-microwave cavity spectrometers.

Item Type:Article
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Blake, G. A.0000-0003-0787-1610
Additional Information:© 2011 American Institute of Physics. Received 8 October 2010; accepted 31 January 2011; published online 17 March 2011. The authors would like to thank the anonymous reviewer for several corrections and useful feedback that was used to much improve the manuscript. This work was funded, in part, by the NASA APRA program, Grant No. NNX-10AC77G, and the NSFCRIF:ID program, Grant No. CHE-0722330. R.B. is further supported by an Omidyar Fellowship.
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Omidyar FellowshipUNSPECIFIED
Subject Keywords:Fabry-Perot resonators, Fourier transform spectra, Fourier transform spectrometers, Q-factor, terahertz spectroscopy
Issue or Number:6
Classification Code:PACS: 07.57.Pt; 07.60.Rd
Record Number:CaltechAUTHORS:20110422-154056926
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Official Citation:Principles and promise of Fabry–Perot resonators at terahertz frequencies R. Braakman and G. A. Blake J. Appl. Phys. 109, 063102 (2011); doi:10.1063/1.3560771 (11 pages)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23435
Deposited By: Ruth Sustaita
Deposited On:25 Apr 2011 20:51
Last Modified:03 Oct 2019 02:46

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