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Wyświetlanie 1-15 z 17
Tytuł:
Global Maxima of the Acousto-Optic Effect in CaWO₄ Crystals
Autorzy:
Andrushchak, A.
Buryy, O.
Demyanyshyn, N.
Hotra, Z.
Mytsyk, B.
Powiązania:
https://bibliotekanauki.pl/articles/1030921.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Fm
78.20.Hp
Opis:
The global maxima of the acousto-optic interaction are theoretically determined for CaWO₄ crystals by extreme surfaces method. As it is shown, the highest value of the acousto-optic figure of merit M₂ is equal to 14.0×10¹⁵ s³/kg and achieved in the case of the diffraction of ordinary or extraordinary light beam on the slow quasi-transversal acoustic wave. At that the incident light wave propagates close to c-axis of the crystal and the corresponding acoustic wave propagates in the direction close to the perpendicular one.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 928-932
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Transfer and f-f Transitions Studied by Photoacoustic Spectroscopy of [R(NO$\text{}_{3}$)$\text{}_{2}$(PicBH)$\text{}_{2}$]NO$\text{}_{3}$ and [R(NO$\text{}_{3}$)$\text{}_{3}$(PicBH)$\text{}_{2}$] Complexes (R - Rare Earth Ion)
Autorzy:
Guskos, N.
Papadopoulos, G.
Majszczyk, J.
Typek, J.
Wabia, M.
Likodimos, V.
Paschalidis, D. G.
Tossidis, I. A.
Aidinis, k.
Powiązania:
https://bibliotekanauki.pl/articles/2035729.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Hp
32.70.-n
Opis:
High-resolution photoacoustic spectra of trinitrato-bis[N-(2-pyridyl-methylene)-N'-benzoyl-hydrazine]R (III), (R = La, Ce, Pr), and binitrato-bis[N-(2-pyridylmethylene)-N'-benzoyl-hydrazine]R(III) nitrate (R=Y, Nd, Eu, Yb, Tb, Gd, Ho, Dy, Er) complexes, in the visual region, were studied for powder samples. Very intense photoacoustic spectra of various shapes were attributed to the intraligand transitions of the π → π* type located mainly on the C=N group and the n → π* transitions located on the carbonyl group. The intensity of these transitions essentially depends on the type of rare earth ions. The existence of f-f electron transitions could influence the relaxation processes, which play an important role in intensity determination of the above transitions. For many investigated samples the energy levels of excited states of rare earth ions were identified (f-f electron transitions). The radiation energy for some of the rare earth ions were compared with the d-d electron transitions of certain copper(II) organometallic complexes, which are very important in biogenic systems. The correlation between ions with localized and extended wave functions is suggested.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 301-313
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Photoacoustic Study of Zn$\text{}_{1-x}$Mg$\text{}_{x}$Se Mixed Crystals
Autorzy:
Męczyńska, H.
Zakrzewski, J.
Łęgowski, S.
Popielarski, M.
Firszt, F.
Szatkowski, J.
Klugiewicz, R.
Łęgowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1877093.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.65.+k
78.20.Hp
Opis:
The photoacoustic spectroscopy with a piezoelectric transducer was employed to evaluate the band gaps of a series of Zn$\text{}_{1-x}$Mg$\text{}_{x}$Se mixed crystals of different composition. The photoacoustic measurements performed at room temperature yield information about the quality of the samples. The photoacoustic spectra were measured using the continuous wave and nanosecond pulse excitation.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 547-550
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Role of Internal Electric Fields in III-N Quantum Structure
Autorzy:
Perlin, P.
Łepkowski, S. P.
Teisseyre, H.
Suski, T.
Grandjean, N.
Massies, J.
Powiązania:
https://bibliotekanauki.pl/articles/2027477.pdf
Data publikacji:
2001-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Hp
78.55.Cr
78.67.Hc
Opis:
Binary nitrides: of wurtzite GaN, AlN, InN, and their solid solutions represent a family of semiconductors of crucial importance for modern optoelectronics. Strained quantum wells, like GaN/AlGaN and specially InGaN/GaN, form active layers of the light emitters working in green-UV part of the spectrum. The operation of these devices strongly depends on the emission spectra of considered quantum structures which are greatly influenced by the presence of built-in electric fields. The electric field acting via quantum confined Stark effect in the mentioned structures changes the energies and intensity of the emitted light. The effect can lead to the spectral shift of a photo- and electroluminescence by many hundreds of meV. In this review we will briefly cover the influence of internal electric fields on both optical and electrical properties of nitride based heterostructures and quantum wells. We would like to draw reader's attention to the usefulness of high-pressure investigation in the study of electric fields in nitrides and to show how the interpretation of these experiments influences the way we calculate the electric fields in the quantum structures.
Źródło:
Acta Physica Polonica A; 2001, 100, 2; 261-270
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phonon Deformation Potentials from Raman Measurements on Semiconductor Membranes
Autorzy:
Trzeciakowski, W.
Martinez-Pastor, J.
Martinez-Criado, G.
Powiązania:
https://bibliotekanauki.pl/articles/1968438.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Fs
78.20.Hp
63.20.Ry
Opis:
It is shown that the phonon deformation potentials in semiconductors can be determined by Raman scattering on hydrostatically and biaxially deformed samples. The complete data includes biaxial deformation in the (100), (111), and (110) planes. Biaxial strain is applied to the sample using the recently developed membrane method. The phonon displacement under biaxial strain can be directly obtained from Raman measurements on a single membrane provided we determine the strain from the splitting of the band gap using e.g. the photoreflectance technique. Alternatively, the ratios of different phonon shifts can supply the necessary information. The method is illustrated with experimental results for GaP.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 1033-1037
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light Induced Ordering of the EL2 Defects in the Metastable State
Autorzy:
Trautman, P.
Baranowski, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/1929711.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
78.50.Ge
78.20.Hp
Opis:
We tried to detect a strain in the crystal induced by the ordering of the EL2 defects in the metastable state by measuring linear dichroism and birefringence. We found that this strain is below the detection limit of our experiments and lower than that induced by 1 MPa of external stress. The observed dependence of orientation of the EL2 defects in the metastable state on the polarization of light used to transform EL2 to the metastable state is consistent with the attribution of the metastability of EL2 to the transformation of the isolated As$\text{}_{Ga}$ to the V$\text{}_{Ga}$A$\text{}_{Si}$ defect and is in conflict with the As$\text{}_{Ga}$-A$\text{}_{Si}$ defect pair model of EL2.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 677-680
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoacoustic Investigation of Absorption Edge of Cd$\text{}_{1-x}$Mg$\text{}_{x}$Se Mixed Crystals
Autorzy:
Firszt, F.
Łęgowski, S.
Męczyńska, H.
Sekulska, B.
Szatkowski, J.
Zakrzewski, J.
Paszkowicz, W.
Powiązania:
https://bibliotekanauki.pl/articles/1968082.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.65.+k
78.20.Hp
78.55.Et
Opis:
The Cd$\text{}_{1-x}$Mg$\text{}_{x}$Se crystals were grown by modified Bridgman method for x ranging from 0 to 0.44. The photoacoustic spectroscopy was employed for evaluation of the band gaps of series Cd$\text{}_{1-x}$Mg$\text{}_{x}$Se mixed crystals with different composition. The photoacoustic spectra were measured at 300 K and 90 K using continuous wave excitation in the range from 400 nm to 800 nm. The increase in the band-gap energy with increasing Mg content is observed. The photoacoustic results are compared with photoluminescence and transmission spectra.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 749-752
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Symmetry of the EL2 Defect in the Metastable State
Autorzy:
Trautman, P.
Baranowski, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/1920969.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
78.20.Hp
78.50.Ge
Opis:
We measured recovery of the optical absorption of EL2 under [100] and [111] uniaxial stress during heating of the crystal. The recovery step, occurring at about 45 K in n-type GaAs, splits into two components under [111] stress, and no splitting is observed under [100] stress. The same behavior under uniaxial stress shows the recovery occurring at 125 K in semi-insulating GaAs. A fraction of centers recovering at lower temperature can be altered by excitation of metastability with polarized light or by excitation under stress. These results indicate that EL2 in the metastable state is trigonally distorted from the tetrahedral symmetry of the ground state.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 609-612
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence Quantum Efficiency of Mn$\text{}^{2+}$ States in ZnSe:Mn as Studied by means of Photoacoustic Spectroscopy
Autorzy:
Męczyńska, H.
Łęgowski, S.
Dąbrowska, W.
Popielarski, M.
Ogielski, Z.
Zakrzewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1929770.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.85.+f
62.65.+k
78.20.Hp
Opis:
The photoacoustic spectroscopy with a piezoelectric transducer was employed to determined the quantum efficiency for low Mn concentration in ZnSe monocrystals. The photoacoustic spectra were measured using the continuous wave excitation and nanosecond pulse method.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 823-825
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acousto-Optic Modulator Driven by Surface Acoustic Waves
Autorzy:
Kakio, S.
Powiązania:
https://bibliotekanauki.pl/articles/1377937.pdf
Data publikacji:
2015-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.79.Jq
43.35.Sx
78.20.Hp
78.20.hb
Opis:
In this paper, an introduction to the design, fabrication, evaluation, and application of acousto-optic modulators using the Bragg diffraction of an optical guided wave in a channel optical waveguide due to a surface acoustic wave is provided. First, the surface acoustic wave mode dependence in the acousto-optic Bragg diffraction was discussed by considering the surface acoustic wave power required for the maximum diffraction $P_100$ calculated using coupled mode theory and the measured $P_100$ in Ti-diffused planar optical waveguides fabricated on $LiNbO_3$ substrates. Next, performances of several devices that the author and the coworkers developed are reviewed. These include a waveguide-type acousto-optic modulator using a tapered crossed-channel proton-exchanged optical waveguide on a 128°-rotated Y-cut $LiNbO_3$ substrate for an optical wavelength of 1.55 μm, a monolithically integrated tandem acousto-optic modulator in which several waveguide-type acousto-optic modulators are connected in tandem on the same substrate, and a waveguide-type acousto-optic modulator in which laser lights of the three primary colors, red, green, and blue, can be modulated by the same modulator at the same driving frequency.
Źródło:
Acta Physica Polonica A; 2015, 127, 1; 15-19
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parametric Amplification in Magnetized Nondegenerate Semiconducting Plasmas
Autorzy:
Jat, K. L.
Neogi, A.
Ghosh, S.
Powiązania:
https://bibliotekanauki.pl/articles/1887743.pdf
Data publikacji:
1991-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Ky
72.20.Ht
73.50.Rb
78.20.Hp
Opis:
Using the straightforward coupled-mode theory, the parametric amplification is analytically investigated in magnetized piezoelectric as well as non-piezoelectric semiconductors. The origin of nonlinear interaction is taken to be in the second-order optical susceptibility χ$\text{}^{(2)}$ arising from the nonlinear induced current density. The threshold value of the pump electric field E$\text{}_{0th}$ is obtained for crystals. E$\text{}_{0th}$ is found to decrease with the rise in magnetic field and fall with the rise in scattering angle. Parametric gain constants are obtained for different situations of practical interest, i.e. (i) for piezoelectric coupling only g$\text{}_{p}$, (ii) for deformation potential coupling only g$\text{}_{d}$, (iii) for both the couplings g$\text{}_{b}$. Numerical investigations reveal that the magnetic field increases the gain. Maximum gains are obtained for backward scattered mode. g$\text{}_{d}$ is always found to be less than g$\text{}_{p}$ and g$\text{}_{b}$. It is also found that g$\text{}_{p}$ and g$\text{}_{b}$ both are identical up to k ≈ x 10$\text{}^{7}$m$\text{}^{-1}$ and for k ≥ 3 x 10$\text{}^{7}$m$\text{}^{-1}$, g$\text{}_{b}$ exceeds g$\text{}_{p}$.
Źródło:
Acta Physica Polonica A; 1991, 79, 6; 829-841
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Symmetry Aspects in EPR Spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ Sites in BiVO$\text{}_{4}$ Single Crystal
Autorzy:
Yeom, T. H.
Choh, S. H.
Rudowicz, Cz.
Powiązania:
https://bibliotekanauki.pl/articles/1920948.pdf
Data publikacji:
1992-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
76.30.Da
61.16.Hn
78.20.Hp
Opis:
Zero-field splitting parameters obtained from EPR X-band experiments of Baran et al. (1985) and Yeom et al. (1992) are reanalyzed. Transformation relations are derived to express the two sets of data in the same axis system. Problems arising from using a truncated zero-field splitting Hamiltonian in fitting the experimental data are elucidated. Low-symmetry aspects in EPR spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ sites in BiVO$\text{}_{4}$ single crystal are considered. Good agreement for orthorhombic parameters b$\text{}_{2}^{0}$ and b$\text{}_{2}^{2}$ is obtained indicating that the centres observed in the two cases are the same Mn centres. The remaining b$\text{}_{k}^{q}$ parameters accounting for the actual site symmetry around Mn$\text{}^{2+}$ impurity which seems to be lower than orthorhombic in the ferroelastic phase cannot be unambiguously determined from the existing EPR data.
Źródło:
Acta Physica Polonica A; 1992, 82, 3; 503-510
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Strong Acoustic Anisotropy on Reflection of Bulk Acoustic Waves in Crystals
Autorzy:
Polikarpova, N.
Powiązania:
https://bibliotekanauki.pl/articles/1811547.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.35.Sx
78.20.Hp
43.25.-x
61.72.-y
Opis:
Propagation and reflection of plane elastic waves in the acousto-optic crystals tellurium dioxide and calomel as well as in the ferroelectric material barium titanate is examined in the paper. The reflection of the waves from a free and flat boundary separating the crystal and the vacuum is investigated in the (001) planes of $TeO_2$, $Hg_2Cl_2$, and $BaTiO_3$ in the case of glancing acoustic incidence on the boundary. The analysis shows that as much as two elastic waves may be reflected from the crystal surface. Energy flow of one of the reflected waves in paratellurite and calomel propagates in a quasi-back direction with respect to the incident energy flow, so that both energy flows are separated by an angle as narrow as a few degrees. It is found that a relative intensity of the unusually reflected wave in the acousto-optic crystals may be close to a unit in a wide variety of crystal cuts. Possible applications of the examined phenomena in acousto-optic devices are discussed in the presentation.
Źródło:
Acta Physica Polonica A; 2008, 114, 6A; A-175-A-182
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New Acousto-Optic Regime of Interaction in Media Possessing Strong Elastic Anisotropy
Autorzy:
Voloshinov, V.
Djakonov, E.
Polikarpova, N.
Powiązania:
https://bibliotekanauki.pl/articles/1383161.pdf
Data publikacji:
2015-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Hp
42.79.Jq
43.35.Sx
43.35.+d
Opis:
We present results on theoretical and first experimental investigation of a new regime of acousto-optic interaction existing in acoustically anisotropic medium. We defined the new regime as "semi-collinear" or "mixed interaction" since it combined properties of the traditional non-collinear diffraction and the pure collinear interaction. The peculiar phenomenon was registered in the tellurium dioxide crystal due to the extremely strong elastic anisotropy of the material. Application of a specific cut of the crystal provided observation of the effect in the middle infrared at the optical wavelength 3.39 μm and at the acoustic frequencies limited to 300 MHz. The observed interaction was characterized by a non-collinear propagation of incident light with respect to acoustic energy flow and simultaneously a collinear propagation of diffracted radiation along the acoustic energy flow. A brief theoretical analysis of the interaction based on wave vector diagrams and two-dimensional coupled wave equations is included in the presentation. Finally, we describe in the paper, the setup and basic details of the carried out acousto-optic experiment.
Źródło:
Acta Physica Polonica A; 2015, 127, 1; 36-42
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic Modes Transformation upon Reflection in Tellurium Dioxide Crystal
Autorzy:
Polikarpova, N.
Voloshinov, V.
Powiązania:
https://bibliotekanauki.pl/articles/1383533.pdf
Data publikacji:
2015-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Hp
42.79.Jq
43.35.Sx
43.35.+d
Opis:
Generation of acoustic shear waves in crystals is one of the main problem of acousto-optics. Launching of the shear waves is much more difficult than the longitudinal modes because of difficulties related to acoustic contact and also because of problems arising from matching of acoustic and electric parameters of piezoelectric transducer. We obtained the transverse waves as a result of longitudinal-shear modes reflection in a crystal. Crystals having the required effect should possess a strong anisotropy of their elastic properties to realize the effective acoustic mode transformation. In this paper, one of the important cases of the acoustic waves reflection is investigated theoretically and experimentally. The research was carried out in the crystal of paratellurite.
Źródło:
Acta Physica Polonica A; 2015, 127, 1; 96-98
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 17

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