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  • 1.
    Anoshkin, Ilya
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Nefedova, Irina
    Lioubtchenko, Dmitri
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Nefedov, Igor
    Räisänen, Antti
    Single walled carbon nanotube quantification method employing the Raman signal intensity2017In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 116, p. 547-552Article in journal (Refereed)
    Abstract [en]

    A new technique for measuring the number of single walled carbon nanotubes (SWCNTs) and their concentration in a carbon nanotube layer is developed in this work. It is based on the G peak intensity of the Raman spectrum, together with precise mass and optical absorbance measurements. The dependence of the number of the carbon nanotubes on the phonon scattering intensity is observed. This method opens an opportunity for the quantitative mapping of sp2 carbon atom distribution in the SWCNT layers with a resolution limited by the focused laser spot size.

  • 2.
    Anoshkin, Ilya V.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Campion, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Lioubtchenko, Dmitri V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Freeze-Dried Carbon Nanotube Aerogels for High-Frequency Absorber Applications2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, ISSN 1944-8244, Vol. 10, no 23, p. 19806-19811Article in journal (Refereed)
    Abstract [en]

    A novel technique for millimeter wave absorber material embedded in a metal waveguide is proposed. The absorber material is a highly porous carbon nanotube (CNT) aerogel prepared by a freeze-drying technique. CNT aerogel structures are shown to be good absorbers with a low reflection coefficient, less than -12 dB at 95 GHz. The reflection coefficient of the novel absorber is 3-4 times lower than that of commercial absorbers with identical geometry. Samples prepared by freeze-drying at -25 degrees C demonstrate resonance behavior, while those prepared at liquid nitrogen temperature (-196 degrees C) exhibit a significant decrease in reflection coefficient, with no resonant behavior. CNT absorbers of identical volume based on wet-phase drying preparation show significantly worse performance than the CNT aerogel absorbers prepared by freeze-drying. Treatment of the freeze-dried CNT aerogel with n- and p-dopants (monoethanolamine and iodine vapors, respectively) shows remarkable improvement in the performance of the waveguide embedded absorbers, reducing the reflection coefficient by 2 dB across the band.

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  • 3.
    Demchenko, P.
    et al.
    ITMO Univ, St Petersburg 197101, Russia..
    Gomon, D.
    ITMO Univ, St Petersburg 197101, Russia..
    Anoshkin, Ilya V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Lioubtchenko, Dmitri
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems. ITMO Univ, St Petersburg 197101, Russia..
    Khodzitsky, M.
    ITMO Univ, St Petersburg 197101, Russia..
    Influence of optical pumping on properties of carbon nanotubes with different geometric parameters in THz frequency range2018In: 2018 43RD INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES (IRMMW-THZ), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    Impact of infrared radiation illumination (980 nm) on the properties of cabon nanotubes (CNT), such as complex conductivity and permittivity, with different geometric parameters (lengths, diameters and with presence/absence graphene oxide layer) in the frequency range of 0.2-1.0 THz was studied.

  • 4. Demchenko, P.
    et al.
    Gomon, D.
    Anoshkin, Ilya V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Lioubtchenko, Dmitri
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Khodzitsky, M.
    Study of optical pumping influence on carbon nanotubes permittivity in THz frequency range2018In: Journal of Physics: Conference Series, Institute of Physics Publishing , 2018, no 5Conference paper (Refereed)
    Abstract [en]

    Equivalent complex permittivity of carbon nanotubes (CNT) was measured with/without light illumination at the frequency range of 0.2-1 THz. It was shown that we can tune the dispersion of the CNT complex conductivity during varying of optical pumping (wavelength of 980 nm). These results mean that CNT is perspective candidate for development of THz tunable attenuators and phase shifters. 

  • 5. Demchenko, P.
    et al.
    Gomon, D.
    Anoshkin, Ilya V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Smirnov, Serguei
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Lioubtchenko, Dmitri
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Khodzitsky, M.
    Study of influence of densification on control of conductivity and spectral characteristics of thin films of carbon nanotubes in terahertz frequency range2018In: EPJ Web of Conferences, EDP Sciences, 2018, article id 06022Conference paper (Refereed)
  • 6.
    Drozdz, Piotr
    et al.
    Inst High Pressure Phys PAS, CENTERA Labs, Warsaw, Poland..
    Campion, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Anoshkin, Ilia
    KTH.
    Xenidis, Nikolaos
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Lioubtchenko, Dmitri, V
    Inst High Pressure Phys PAS, CENTERA Labs, Warsaw, Poland..
    W-band waveguide embedded nanofiber absorber2021In: 2021 46Th International Conference On Infrared, Millimeter And Terahertz Waves (IRMMW-THZ), Institute of Electrical and Electronics Engineers (IEEE) , 2021Conference paper (Refereed)
    Abstract [en]

    A novel type of absorber integrate into a standard WR-10 metal waveguide of is developed and measured. The absorber is based on alumina nanofibers covered with single or multi- carbon layers. Employing this technique for the CNT based absorbers offers a material with micron scales-oriented 3D microstructures, that is hybrid alumina nanofibers covered with carbon layer. These microstructures result in a low level of reflectance and good absorbance at 75-110 GHz frequency band due to the highly porous and low conductivity.

  • 7. Gomon, D.
    et al.
    Gusev, S.
    Demchenko, P.
    Anoshkin, Ilya V.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Lioubtchenko, Dmitri
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Khodzitsky, M.
    Opticaly tunable conductivity of carbon nanotubes in terahertz frequency range2018In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2018Conference paper (Refereed)
    Abstract [en]

    Impact of infrared radiation illumination (980 nm) on the properties of carbon nanotubes (CNT), such as complex conductivity and permittivity, with different geometric parameters in the frequency range of 0.2-1.0 THz was studied. 

  • 8. Lioubtchenko, Dmitri V.
    et al.
    Anoshkin, Ilya
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Nefedova, I. I.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Raisanen, A. V.
    W-band phase shifter based on optimized optically controlled carbon nanotube layer2017In: 2017 IEEE MTT-S International Microwave Symposium (IMS), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1188-1191, article id 8058815Conference paper (Refereed)
    Abstract [en]

    Phase shifting in a dielectric rod waveguide (DRW), loaded with carbon nanotube (CNT) layers of different thickness, was studied experimentally under light illumination in the frequency range of 75-110 GHz. The dependence of efficiency of the phase shifting, in terms of phase shift per light intensity and millimeter wave attenuation, on the optical transparency of the CNT-layer is investigated in this paper. The best result, a phase shifter of 0-15° with less than 0.1 dB additional signal loss in the W-band was achieved for a 95% transparent CNT layer at 23 mW/mm2 light intensity of a tungsten halogen lamp (main radiation spectrum is 550-680 nm). The overall insertion loss of the phase shifter including two DRW tapering sections serving as transitions to rectangular waveguides are 3 to 5 dB in the W-band, about 2 dB is attributed to the CNT DRW section. This comprises, for the first time, an optically-controlled CNT-based DRW phase shifter with phase shift and insertion loss levels suitable for practical applications.

  • 9.
    Lyubchenko, Dmitri
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Smirnov, Serguei
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Anoshkin, Ilya V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Millimeter Wave Beam Steering Based on Optically Controlled Carbon Nanotube Layers2018Conference paper (Refereed)
    Abstract [en]

    In this paper, the dielectric constant changing of thin carbon nanotube layers under light illumination was used for phase shifter development in dielectric rod waveguides. This designed phase shifter was introduced to the dielectric rod waveguide dual-antenna array. The measurements of the beam steering at 90 GHz of the dielectric rod antenna array, covered with carbon nanotubes, were carried out.

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  • 10.
    Smirnov, Serguei
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Anoshkin, Ilya V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Demchenko, Petr
    ITMO University.
    Gomon, Daniel
    ITMO University.
    Lioubtchenko, Dmitri V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Khodzitsky, Mikhail
    ITMO University.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Optically controlled dielectric properties of single-walled carbon nanotubes for terahertz wave applications2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 26, p. 12291-12296Article in journal (Refereed)
    Abstract [en]

    Materials with tunable dielectric properties are valuable for a wide range of electronic devices, but are often lossy at terahertz frequencies. Here we experimentally report the tuning of the dielectric properties of single-walled carbon nanotubes under light illumination. The effect is demonstrated by measurements of impedance variations at low frequency as well as complex dielectric constant variations in the wide frequency range of 0.1-1 THz by time domain spectroscopy. We show that the dielectric constant is significantly modified for varying light intensities. The effect is also practically applied to phase shifters based on dielectric rod waveguides, loaded with carbon nanotube layers. The carbon nanotubes are used as tunable impedance surface controlled by light illumination, in the frequency range of 75-500 GHz. These results suggest that the effect of dielectric constant tuning with light, accompanied by low transmission losses of the carbon nanotube layer in such an ultra-wide band, may open up new directions for the design and fabrication of novel Terahertz and optoelectronic devices.

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  • 11.
    Smirnov, Serguei
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Anoshkin, Ilya V.
    Generalov, Andrey
    Lioubtchenko, Dmitri
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Wavelength-dependent photoconductivity of single-walled carbon nanotube layers2019In: RSC Advances, E-ISSN 2046-2069, Vol. 9, no 26, p. 14677-14682Article in journal (Refereed)
    Abstract [en]

    A number of electronic devices such as phase shifters, polarizers, modulators, and power splitters are based on tunable materials. These materials often do not meet all the requirements namely low losses, fast response time, and technological compatibility. Novel nanomaterials, such as single-walled carbon nanotubes, are therefore widely studied to fill this technological gap. Here we show how the dielectric constant of single-walled carbon nanotube layers can be substantially modified by illuminating them due to unique light–matter interactions. We relate the optical excitation of the nanotube layers to the illumination wavelength and intensity, by resistance and capacitance measurements. The dielectric constant is modified under laser illumination due to the change of material polarization and free carrier generation, and is shown to not be temperature-related. The findings indicate that SWCNT layers are a prospective tunable optoelectronic material for both high and low frequency applications.

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  • 12.
    Smirnov, Serguei
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Anoshkin, Ilya V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Lioubtchenko, Dmitri
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Carbon Nanotube Layer Modeling for Computer Simulation of Optically Controlled Phase Shifters2018Conference paper (Refereed)
    Abstract [en]

    We propose an approach for efficient modeling of thin carbon nanotube layers for full-wave device simulations without increasing the number of simulation mesh cells. A surface impedance, used in computer simulations, is calculated from the dielectric constant of the material. The dielectric constant is modeled by a Drude–Lorentz resonance, fitted to experimental results. The approach allowed to study the nanotube-induced losses and finite-size resonance effects in optically-controlled, dielectric rod waveguide-based phase shifters. The correctness of the model was verified both by the simulated and the measured S-parameters in the W-band.

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  • 13.
    Smirnov, Serguei
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Anoshkin, Ilya V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Lioubtchenko, Dmitri
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Millimeter Wave Phase Shifter Based on Optically Controlled Carbon Nanotube Layers2018Conference paper (Refereed)
    Abstract [en]

    Surfaces with tunable impedance are usually lossy at high frequencies, which limits the design of millimeter wave and Terahertz devices. This work experimentally demonstrates a phase shifter based on single-walled carbon nanotubes and dielectric rod waveguides in the 220–330 GHz frequency range. Thin carbon nanotube layers are used as a tunable impedance surface with the dielectric properties optically controlled by laser illumination.

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