Developments in Terahertz Ellipsometry: Portable Spectroscopic Quasi-Optical Ellipsometer-Reflectometer and Its Applications

Belyaeva, A. I.; Галуза, А. А.; Коленов, И. В.; Mizrakhy, Sergey

doi:10.1007/s10762-020-00762-7

Cited by 19 publications

(2 citation statements)

References 39 publications

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“…In spite of the difficulties in the direct measurements of the ellipsometric angles with a high precision, we believe that results presented here show that THz-TDSE combined with a careful calibration procedure in time domain can give precious information with an unprecedented level of accuracy on the complex optical response of different classes of materials. For the extinction coefficient in particular, only a few experimental works to compare with are present in recent literature, reporting high mismatches 35 , or negative values 26 , or no values at all 24 .…”

Section: Resultsmentioning

confidence: 99%

Accurate THz Ellipsometry Using Calibration in Time Domain

Mazaheri

Koral

Andreone

2021

Preprint

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We report on the realisation of a customized THz Time Domain Spectroscopic Ellipsometer (THz-TDSE) based on fiber-coupled photoconductive antennas, operating in a wide range of incident angles and allowing also standard transmission spectroscopy without any optical realignment. To ensure accurate parameter extraction for a broad range of materials, we developed a fast and effective algorithm-assisted method to calibrate the setup and compensate for the nonideality in the response of the THz system. The procedure allows to minimise errors induced by imperfect response of the antennas and polarizers, imprecise setting of the impinging and receiving angles in the goniometric mechanical arms, and unavoidable mismatches in the THz beam optics. Differently from other calibration methods applied in the literature, our approach compares in time domain the ellipsometric derived electric field s- and p-polarised components at a given angle of incidence with the reconstructed ones, attained by using the complex dielectric function of a known sample. The calibrated response is determined with high precision by setting the system in transmission mode. In order to validate the technique, ellipsometric measurements have been carried out at various angle of incidences on a number of materials both in solid and liquid form, and their data compared with what obtained by conventional THz spectroscopy. Results show that THz-TDSE accompanied with an accurate calibration procedure is an effective technique for material characterization, especially in case of samples with a high absorption rate that are not easily investigated through transmission measurements.

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Section: Resultsmentioning

confidence: 99%

Accurate THz Ellipsometry Using Calibration in Time Domain

Mazaheri

Koral

Andreone

2021

Preprint

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“…Due to reducing radiation losses, such coupling elements should provide a higher powersummation factor of individual sources in the OR. The polarization wire gratings are also used in several devices and circuits in the higher frequency region [19], for example, in the scheme of a Michelson polarization interferometer [20]. Instead of a waveguide tee and waveguide elements, a polarization grating was used, installed in a quasi-optical beam splitter together with functional elements based on a hollow dielectric beam guide.…”

Section: Introductionmentioning

confidence: 99%

Power Summation in an Open Resonator with Aperture Coupling Elements

Kuzmichev,

Muzychishin,

Popkov

et al. 2024

AEM

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The paper considers the powers summation of two sources in a hemispherical open resonator (OR). A scheme with a E- tee waveguide was used. The study was carried out in the four-millimeter wavelength range. In the resonator, the first highest axially-asymmetric ТЕМ10q mode is excited with the help of aperture coupling elements. The coupling elements are pyramidal horns located in the center of a flat mirror, with apertures of 6.9×9.6 mm and length of 85 mm. There are one-dimensional E- polarized diffraction gratings with periods of 0.2 mm, 0.4 mm, 0.6 mm in the apertures of the coupling elements. It is shown that the maximum power summation coefficient of two sources in an OR using aperture coupling elements, in the apertures of which a one-dimensional diffraction grating with a period of 0.6 mm is located, is 90%. The high excitation efficiency in the resonator of the TEM10q mode with the help of aperture coupling elements ensures the angular selection of the oscillation spectrum of such a resonant system. It has been established that to sum the powers of two sources in the OR, it is advisable to use not the TEM10q mode but TEM20q.

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Characterization of Ultrathin Conductive Films Using a Simplified Approach for Terahertz Time-Domain Spectroscopic Ellipsometry

Nagai,

Watanabe,

Imamura

et al. 2024

J Infrared Milli Terahz Waves

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We present two ideas to simplify the measurement and analysis of terahertz time-domain spectroscopic ellipsometry data of ultrathin films. The measurement is simplified by using a specially designed sample holder with mirrors, which can be mounted on a cryostat. It allows us to perform spectroscopic ellipsometry by simply inserting the holder into a conventional terahertz spectroscopy system for measurements in transmission geometry. The analysis of the obtained data is simplified by considering a single interface with a certain sheet conductivity $${\sigma }_{s}$$ σ s (since the film thickness is significantly smaller than the wavelength of the terahertz light). We demonstrate the application of these ideas by evaluating the sheet conductivities of two perovskite rare-earth nickelate thin films in the temperature range 78–478 K. The use of this particular analytical method and the sample holder design will help to establish terahertz time-domain spectroscopic ellipsometry as a characterization technique for ultrathin films.

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Developments in Terahertz Ellipsometry: Portable Spectroscopic Quasi-Optical Ellipsometer-Reflectometer and Its Applications

Cited by 19 publications

References 39 publications

Accurate THz Ellipsometry Using Calibration in Time Domain

Accurate THz Ellipsometry Using Calibration in Time Domain

Power Summation in an Open Resonator with Aperture Coupling Elements

Characterization of Ultrathin Conductive Films Using a Simplified Approach for Terahertz Time-Domain Spectroscopic Ellipsometry

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