TY - JOUR

T1 - Silicon kinoform cylindrical lens with low surface roughness for high-power terahertz radiation

AU - Kononenko, Taras V.

AU - Knyazev, Boris A.

AU - Sovyk, Dmitry N.

AU - Pavelyev, Vladimir S.

AU - Komlenok, Maxim S.

AU - Komandin, Gennadii A.

AU - Konov, Vitaly I.

N1 - Funding Information: The work was supported by Russian Ministry of Education and Science (Project 3.2608.2017/4.6). SEM investigations were carried out at D. Mendeleev Center for collective use of scientific equipment at D. Mendeleev University of Chemical Technology of Russia. Experiments on the Novosibirsk free electron laser were carried out using the equipment of the Siberian center of synchrotron and terahertz radiation. The authors thank O.E. Kameshkov for the numerical calculations. Publisher Copyright: © 2019 Elsevier Ltd Copyright: Copyright 2019 Elsevier B.V., All rights reserved.

PY - 2020/3

Y1 - 2020/3

N2 - Precise microstructuring of silicon with short laser pulses is a promising technique for fabrication of kinoform diffractive optical elements (DOEs) for high-power THz radiation. Micrometer-scale surface roughness being a typical result of the silicon microstructuring with laser is an important factor reducing optical performance of the fabricated DOEs. We demonstrate here that proper optimization of the processing conditions under profiling of high-resistance silicon surface by 1 ps laser pulses at λ = 1.03 μm allows formation of cylindrical Fresnel lens with the surface roughness of 0.5–1.2 µm being one order of magnitude smaller than reported earlier. Testing of the fabricated lens with a free electron laser at the wavelength of 141 μm has shown that the laser-machined silicon retains its original transmittance. Diffraction efficiency (0.93 ± 0.06) and deviation of the laser intensity profile in the lens focus from the theoretical expectations have been evaluated. Additionally, influence of the surface roughness on transmittance of the laser-machined silicon in the wavelength range of 95–400 μm was studied by means of time domain spectroscopy.

AB - Precise microstructuring of silicon with short laser pulses is a promising technique for fabrication of kinoform diffractive optical elements (DOEs) for high-power THz radiation. Micrometer-scale surface roughness being a typical result of the silicon microstructuring with laser is an important factor reducing optical performance of the fabricated DOEs. We demonstrate here that proper optimization of the processing conditions under profiling of high-resistance silicon surface by 1 ps laser pulses at λ = 1.03 μm allows formation of cylindrical Fresnel lens with the surface roughness of 0.5–1.2 µm being one order of magnitude smaller than reported earlier. Testing of the fabricated lens with a free electron laser at the wavelength of 141 μm has shown that the laser-machined silicon retains its original transmittance. Diffraction efficiency (0.93 ± 0.06) and deviation of the laser intensity profile in the lens focus from the theoretical expectations have been evaluated. Additionally, influence of the surface roughness on transmittance of the laser-machined silicon in the wavelength range of 95–400 μm was studied by means of time domain spectroscopy.

KW - DIFFRACTIVE OPTICS

KW - FRESNEL LENS

KW - FABRICATION

UR - http://www.scopus.com/inward/record.url?scp=85075473112&partnerID=8YFLogxK

U2 - 10.1016/j.optlastec.2019.105953

DO - 10.1016/j.optlastec.2019.105953

M3 - Article

AN - SCOPUS:85075473112

VL - 123

JO - Optics and Laser Technology

JF - Optics and Laser Technology

SN - 0030-3992

M1 - 105953

ER -