Organic crystal-based THz source for complex refractive index measurements of window materials using single-shot THz spectroscopy

AbstractWe employed N-benzyl-2-methyl-4-nitroaniline (BNA) crystals bonded on substrates of different thermal conductivity to generate THz radiation by pumping with 800 nm laser pulses. Crystals bonded on sapphire substrate provided four times more THz yield than glass substrate. A pyrodetector and a single-shot electro-optic (EO) diagnostic were employed for measuring the energy and temporal characterisation of the THz pulse. Systematic studies were carried out for the selection of a suitable EO crystal, which allowed accurate determination of the emitted THz spectrum from both substrates. Subsequently, the THz source and single-shot electro-optic detection scheme were employed to measure the complex refractive index of window materials in the THz range.

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Effect of tissue fluid on accurate determination of the complex refractive index of animal tissue

Journal of Biomedical Optics ◽

10.1117/1.jbo.17.7.075011 ◽

2012 ◽

Vol 17 (7) ◽

pp. 0750111 ◽

Cited By ~ 3

Author(s):

Jin Wang ◽

Qing Ye ◽

Zhi-Chao Deng ◽

Wen-Yuan Zhou ◽

Teng-Qian Sun ◽

...

Keyword(s):

Refractive Index ◽

Complex Refractive Index ◽

Accurate Determination ◽

Animal Tissue ◽

Tissue Fluid

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Accurate determination of the complex refractive index of solid tissue-equivalent phantom

10.1117/12.919832 ◽

2012 ◽

Author(s):

Jin Wang ◽

Qing Ye ◽

Zhichao Deng ◽

Wenyuan Zhou ◽

Chunping Zhang ◽

...

Keyword(s):

Refractive Index ◽

Complex Refractive Index ◽

Accurate Determination ◽

Solid Tissue ◽

Tissue Equivalent ◽

Tissue Equivalent Phantom

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Broadband spectroscopy of astrophysical ice analogues

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935619 ◽

2019 ◽

Vol 629 ◽

pp. A112 ◽

Cited By ~ 8

Author(s):

B. M. Giuliano ◽

A. A. Gavdush ◽

B. Müller ◽

K. I. Zaytsev ◽

T. Grassi ◽

...

Keyword(s):

Refractive Index ◽

Optical Properties ◽

Time Domain ◽

Complex Refractive Index ◽

Far Infrared ◽

Infrared Region ◽

Thz Radiation ◽

The Real ◽

Thz Range ◽

The Time Domain

Context. Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region. Aims. Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range. Methods. We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data. Results. The complex refractive index in the wavelength range 1 mm–150 μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature. Conclusions. The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.

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Optical Characterization of Ultra-Thin Films of Azo-Dye-Doped Polymers Using Ellipsometry and Surface Plasmon Resonance Spectroscopy

Photonics ◽

10.3390/photonics8020041 ◽

2021 ◽

Vol 8 (2) ◽

pp. 41

Author(s):

Najat Andam ◽

Siham Refki ◽

Hidekazu Ishitobi ◽

Yasushi Inouye ◽

Zouheir Sekkat

Keyword(s):

Refractive Index ◽

Optical Properties ◽

Surface Plasmon Resonance ◽

Surface Plasmon ◽

Spectroscopic Ellipsometry ◽

Plasmon Resonance ◽

Complex Refractive Index ◽

Resonance Spectroscopy ◽

Doped Polymers

The determination of optical constants (i.e., real and imaginary parts of the complex refractive index (nc) and thickness (d)) of ultrathin films is often required in photonics. It may be done by using, for example, surface plasmon resonance (SPR) spectroscopy combined with either profilometry or atomic force microscopy (AFM). SPR yields the optical thickness (i.e., the product of nc and d) of the film, while profilometry and AFM yield its thickness, thereby allowing for the separate determination of nc and d. In this paper, we use SPR and profilometry to determine the complex refractive index of very thin (i.e., 58 nm) films of dye-doped polymers at different dye/polymer concentrations (a feature which constitutes the originality of this work), and we compare the SPR results with those obtained by using spectroscopic ellipsometry measurements performed on the same samples. To determine the optical properties of our film samples by ellipsometry, we used, for the theoretical fits to experimental data, Bruggeman’s effective medium model for the dye/polymer, assumed as a composite material, and the Lorentz model for dye absorption. We found an excellent agreement between the results obtained by SPR and ellipsometry, confirming that SPR is appropriate for measuring the optical properties of very thin coatings at a single light frequency, given that it is simpler in operation and data analysis than spectroscopic ellipsometry.

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