3.9 THz spatial filter based on a back-to-back Si-lens system
Optics Express, vol. 28, pp. 32693
Abstract
We present a terahertz spatial filter consisting of two back-to-back (B2B) mounted elliptical silicon lenses and an opening aperture defined on a thin gold layer between the lenses. The beam filtering efficiency of the B2B lens system is investigated by simulation and experiment. Using a unidirectional antenna coupled 3rd-order distributed feedback (DFB) quantum cascade laser (QCL) at 3.86 THz as the source, the B2B lens system shows 72% transmissivity experimentally with a fundamental Gaussian mode as the input, in reasonably good agreement with the simulated value of 80%. With a proper aperture size, the B2B lens system is capable of filtering the non-Gaussian beam from the QCL to a nearly fundamental Gaussian beam, where Gaussicity increases from 74% to 99%, and achieves a transmissivity larger than 30%. Thus, this approach is proven to be an effective beam shaping technique for QCLs, making them to be suitable local oscillators in the terahertz range with a Gaussian beam. Besides, the B2B lens system is applicable to a wide frequency range if the wavelength dependent part is properly scaled.
Authors 11
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Space Research Organisation Netherlands · Delft University of Technology
Affiliation as printed
Optics Research Group, Department of Imaging Physics, Delft University of Technology, Delft, 2628 CJ, The Netherlands
SRON Netherlands Institute for Space Research, Groningen/Utrecht, 9747 AD/3584 CA, The Netherlands
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University of Groningen · Space Research Organisation Netherlands
Affiliation as printed
Kapteyn Astronomical Institute, University of Groningen, Groningen, 9747 AD, The Netherlands
SRON Netherlands Institute for Space Research, Groningen/Utrecht, 9747 AD/3584 CA, The Netherlands
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Space Research Organisation Netherlands
Affiliation as printed
SRON Netherlands Institute for Space Research, Groningen/Utrecht, 9747 AD/3584 CA, The Netherlands
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Space Research Organisation Netherlands
Affiliation as printed
SRON Netherlands Institute for Space Research, Groningen/Utrecht, 9747 AD/3584 CA, The Netherlands
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Space Research Organisation Netherlands
Affiliation as printed
SRON Netherlands Institute for Space Research, Groningen/Utrecht, 9747 AD/3584 CA, The Netherlands
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Massachusetts Institute of Technology
Affiliation as printed
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Space Research Organisation Netherlands · Massachusetts Institute of Technology
Affiliation as printed
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
SRON Netherlands Institute for Space Research, Groningen/Utrecht, 9747 AD/3584 CA, The Netherlands
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University of Groningen · Space Research Organisation Netherlands
Affiliation as printed
Kapteyn Astronomical Institute, University of Groningen, Groningen, 9747 AD, The Netherlands
SRON Netherlands Institute for Space Research, Groningen/Utrecht, 9747 AD/3584 CA, The Netherlands
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University of Groningen · Space Research Organisation Netherlands · Delft University of Technology
Affiliation as printed
Kapteyn Astronomical Institute, University of Groningen, Groningen, 9747 AD, The Netherlands
Optics Research Group, Department of Imaging Physics, Delft University of Technology, Delft, 2628 CJ, The Netherlands
SRON Netherlands Institute for Space Research, Groningen/Utrecht, 9747 AD/3584 CA, The Netherlands
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