39 THz spatial filter based on a back-to-back Si-lens system
Name
oe-28-22-32693.pdf
Description
Published version
Size
3.38 MB
Format
Adobe PDF
Checksum (MD5)
d2c1243760a9480af680ca57f46d4533
Author(s)
Gan, Yuner
Mirzaei, Behnam
van der Poel, Sebastiaan
Silva, Jose RG
Finkel, Matvey
Eggens, Martin
Ridder, Marcel
Khalatpour, Ali
Hu, Qing
van der Tak, Floris
Date Issued
2020
Journal
Optics Express
Publisher
The Optical Society
Citation
Gan, Yuner, Mirzaei, Behnam, van der Poel, Sebastiaan, Silva, Jose RG, Finkel, Matvey et al. 2020. "39 THz spatial filter based on a back-to-back Si-lens system." Optics Express, 28 (22).
Version
Final published version
Abstract
© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. 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.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
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DOI of Published Version
https://doi.org/10.1364/OE.410446
