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Tytuł:
Influence of Modulation Detection Threshold on Speech Intelligibility
Autorzy:
Leo, K.
Powiązania:
https://bibliotekanauki.pl/articles/1504420.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.55.Hy
Opis:
Speech intelligibility in classrooms and lecture halls was investigated. Acoustical measurements in the rooms have been performed, with special concern about 125 ms of early decay phenomenon. Weighting function of early reflections relative energy derived from modulation threshold and speech modulation spectrum of signal is proposed.
Źródło:
Acta Physica Polonica A; 2011, 119, 6A; 1023-1026
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light Modulation in Elliptical-Core Liquid Crystal Fibers
Autorzy:
Nasiłowski, T.
Woliński, T. R.
Powiązania:
https://bibliotekanauki.pl/articles/2008248.pdf
Data publikacji:
1999-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.-i
Opis:
An original idea of external parameters (electric field, temperature, pressure etc.) monitoring is presented. After the theoretical analysis of the light modulation in a liquid crystal and elliptical-core anisotropic fiber the latest experimental results are reported. Due to measurands-induced changes in birefringence and propagation conditions the liquid crystal and elliptical-core fiber uniting unique advantages of liquid crystals and quality of fiber technology acts as a sensing medium and can be used for continuous monitoring of different external parameters.
Źródło:
Acta Physica Polonica A; 1999, 95, 5; 767-775
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conductance Modulation in Semiconductor Microstructure with Periodic Array of Micromagnets
Autorzy:
Tralle, I.
Powiązania:
https://bibliotekanauki.pl/articles/1992495.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Gd
73.50.Bk
Opis:
A simple theory for the Aharonov-Bohm-like effect (dynamical phase) in semiconductor microstructure, is presented in a paper, assuming a "ballistic spin transport". If in one of the arms of microstructure there is an additional periodic magnetic field, the spin wave function acquires a phase shift due to additional spin precession about that field. By introducing quaternion representation of the elements of propagation matrices, one can calculate the transition coefficient of the structure. It is shown that the deep modulation of the conductance could be achieved.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 603-610
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modulation Spectroscopy of Reduced Dimensional Semiconductor Systems
Autorzy:
Pollak, F. H.
Powiązania:
https://bibliotekanauki.pl/articles/1933677.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.-w
78.66.Fd
78.40.Fy
Opis:
This paper reviews the background of modulation spectroscopy, particularly electromodulation, presents some recent room temperature results having both fundamental and technological significance, including two-dimensional electron gas effects in modulation-doped, pseudomorphic GaAlAs/InGaAs/GaAs single quantum wells (HΕΜΤ structures), quantum well laser structures and process-induced damage in quantum dot arrays fabricated by reactive ion etching.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 581-590
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Controlling Light by Light: Optical Modulation in Chiral Nematics
Autorzy:
Sierakowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/2008249.pdf
Data publikacji:
1999-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.81.Wg
42.70.Df
Opis:
Nonlinear optics of chiral liquid-crystalline media have been in scope of our interest for several years. Our previous observations in the subject had already been reported. This paper discusses a possibility of utilising the nonlinear optical properties of liquid crystals for practical purposes. We discuss an idea of "in line" intensity measurements of laser beam. The idea is based on two optical phenomena which are observed in liquid-crystalline media possessing a periodically stratified structure: nonlinear optical effect and selective light reflection. The effects start to appear by activating light intensities of the order of MW/m$\text{}^{2}$, so the method can be potentially applied at present to high-intensity light beams (corresponding laser power is approximately 0.1 W), although there are now also prospects to lower this value significantly.
Źródło:
Acta Physica Polonica A; 1999, 95, 5; 777-782
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Amplitude Modulation and Demodulation in Strain Dependent Diffusive Semiconductors
Autorzy:
Ghosh, S.
Yadav, N.
Powiązania:
https://bibliotekanauki.pl/articles/2047356.pdf
Data publikacji:
2007-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.35.Mw
72.50.+b
66.30.-h
Opis:
In communication processes, amplitude modulation is very helpful to save power by using a single band transmission. Thus in this paper authors have explored the possibility of amplitude modulation as well as demodulation of an electromagnetic wave in a transversely magnetized electrostrictive semiconductor. The inclusion of carrier diffusion and phenomenological damping coefficient in the nonlinear laser-semiconductor plasma interaction adds a new dimension to the analysis present in this paper. This problem is analyzed in different wave number regimes over a wide range of cyclotron frequencies. It is found that the complete absorption of the waves takes place in all the possible wavelength regimes when the cyclotron frequency (ω$\text{}_{c}$) becomes exactly equal to (ν$\text{}^{2}$+ω$\text{}_{0}^{2}$)$\text{}^{1}\text{}^{/}\text{}^{2}$ in absence of damping parameter. It has also been seen that diffusion of charge carriers modifies amplitude modulation and demodulation processes significantly. The damping parameter plays a very important role in deciding the parameter range and selecting the side band mode that will be modulated by the above-mentioned interaction.
Źródło:
Acta Physica Polonica A; 2007, 112, 1; 29-40
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Subdiffusion with External Time Modulation
Autorzy:
Wojnar, R.
Powiązania:
https://bibliotekanauki.pl/articles/1812233.pdf
Data publikacji:
2008-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.40.Jc
05.70.Ln
82.39.Rt
87.18.Hf
89.65.Gh
89.65.Lm
Opis:
A subdiffusion process, similar to a Zeldovich-Kompaneets heat conduction process, is defined by a nonlinear diffusion equation in which the diffusion coefficient takes the form D=a(t)f^n, where a=a(t) is an external time modulation, n is a positive constant, and f=f(x, t) is a solution to the nonlinear diffusive equation. It is shown that a Zeldovich-Kompaneets solution satisfies the subdiffusion equation if a=a(t) is replaced by the mean value of a. Also, a solution to the subdiffusion equation is constructed that may be useful in description of biological, social, and financial processes.
Źródło:
Acta Physica Polonica A; 2008, 114, 3; 607-611
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Critical Points of the Structure Amplitude for the Case of One-Dimensional Displacive Modulation
Autorzy:
Śliwińska, T.
Gusin, P.
Warczewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2043371.pdf
Data publikacji:
2005-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.44.Fw
61.10.Dp
Opis:
The behavior of the structure amplitude is analyzed in terms of the harmonics of a modulation function for the case of one-dimensional longitudinal displacive modulation. This modulation function is given by a finite series of N sine functions. It turns out that: (1) for the large values of the amplitudes of the modulation function the structure amplitude tends to zero for the arbitrary values of the order m of the satellite reflections; (2) for certain values of the amplitudes of the modulation function the modulus of the structure amplitude assumes its maximum value and (3) for the latter case the intensity of an arbitrary satellite reflection is a function of the intensities of both the closest main reflection and the intensities of the finite set of the neighbor satellite reflections.
Źródło:
Acta Physica Polonica A; 2005, 107, 6; 917-931
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymmetrically Shaped Pseudomorphic Modulation Doped Structure for Microwave Detection
Autorzy:
Kozič, A.
Paškevič, Č.
Sužiedėlis, A.
Gradauskas, J.
Ašmontas, S.
Szerling, A.
Wrzesińska, H.
Powiązania:
https://bibliotekanauki.pl/articles/2047175.pdf
Data publikacji:
2006-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.30.De
72.30.+q
Opis:
In this paper we propose a microwave detector based on a AlGaAs/InGaAs/GaAs structure. Its operation relies on non-uniform carrier heating of the two-dimensional electron gas in the microwave electric fields which is a result of the asymmetric shape of the device fabricated on the base of pseudomorphic modulation doped AlGaAs/InGaAs/GaAs structure. The voltage sensitivity of the device at nitrogen temperature is 38 V/W for 10 GHz radiations and is higher compared to that of modulation doped AlGaAs/GaAs of the same configuration.
Źródło:
Acta Physica Polonica A; 2006, 110, 6; 845-849
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dependence of Modulation Bandwidth on Size of Optical Injection Locked Semiconductor Ring Laser
Autorzy:
Memon, M.
Fathallah, H.
Powiązania:
https://bibliotekanauki.pl/articles/1290582.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.55.Wd
42.65.Re
42.60.By
42.65.Pc
Opis:
It has been successfully investigated for the first time that strength of optical injection locking also depends on the size of semiconductor ring laser. Theoretical study for frequency response of optical injection locking semiconductor ring laser in the master slave configuration using direct, amplitude and phase modulation of master laser is discussed. In the unidirectional regime the locking range of semiconductor ring laser becomes wider when semiconductor ring laser with smaller size is used. Simulation results predict an incredible enhancement in the modulation bandwidth (> 500 GHz) of the slave semiconductor ring laser when used with smaller laser cavity length (50 μm) in the stable unidirectional regime.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 462-464
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhanced Electro-Optic Modulation Performance in Optical Buffers by Slowing Light in Optimized Photonic Crystal Slab Structures
Autorzy:
Bagci, F.
Akaoglu, B.
Powiązania:
https://bibliotekanauki.pl/articles/1195299.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Qs
42.79.Hp
42.65.Pc
Opis:
Slow light holds the key to advanced optical buffering and time-domain optical signal processing technologies. Photonic crystal based optical buffers are particularly attractive due to their nanoscale size, room temperature operation, and enhanced field dependent nonlinear response associated with the presence of slow light. In this study, the slow light and electro-optic modulation characteristics of a line-defect Si photonic crystal slab with triangular arrangement of holes filled with an electro-optic polymer (n = 1.6) are investigated by three-dimensional plane-wave expansion and finite-difference time-domain methods. The first rows adjacent to the line-defect are shifted gradually in the direction of light propagation and a slow light region with a high group index below the light-line is obtained for a shifting amount between 0.22a and 0.27a. For the photonic crystal configuration with 0.22a shifted rows, under modulated voltage change, the average group index is found to be decreasing with an increase in the bandwidth. The results show that the low group velocity supports a large delay time in a small modulated voltage variation. A linear change of group index with modulated voltage is obtained and the modulation sensitivity of central wavelength is obtained as 9.45 nm/V for a delay line length of 0.5 mm. Almost the same buffer capacity and bit length are found which provides the control of delay time flexibly while keeping the buffer capacity and the bit length almost unchanged.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 611-614
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optically Detected SdH Oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te Modulation Doped Quantum Wells
Autorzy:
Shen, J. X.
Ossau, W.
Fischer, F.
Waag, A.
Landwehr, G.
Powiązania:
https://bibliotekanauki.pl/articles/1943817.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Et
Opis:
Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 1033-1037
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo Analysis of the Dynamic Behavior οf InAlAs/InGaAs Velocity Modulation Transistors: A Geometrical Optimization
Autorzy:
Vasallo, B.
González, T.
Pardo, D.
Mateos, J.
Powiązania:
https://bibliotekanauki.pl/articles/1505612.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.30.De
85.30.Tv
Opis:
The influence of the geometry on the dynamic behavior of InAlAs/InGaAs velocity modulation transistors is analyzed by means of a Monte Carlo simulator in order to optimize the performance of this new type of transistor. In velocity modulation transistors, based on the topology of a double-gate high electron mobility transistor, the source and drain electrodes are connected by two channels with different mobilities, and electrons are transferred between both of them by changing the gate voltages in differential mode. Consequently, the drain current is modulated while keeping the total carrier density constant, thus in principle avoiding capacitance charging/discharging delays. However, the low values taken by the transconductance, as well as the high capacitance between the two gates in differential-mode operation, lead to a deficient dynamic performance. This behavior can be geometrically optimized by increasing the mobility difference between the two channels, by increasing the channel width and, mainly, by reducing the gate length, with a higher immunity to short channel effects than the traditional architectures.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 193-195
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ferroelectric Field Effect Transistor Based on Modulation Doped CdTe/CdMgTe Quantum Wells
Autorzy:
Kolkovsky, V.
Wojciechowski, T.
Wojtowicz, T.
Karczewski, G.
Powiązania:
https://bibliotekanauki.pl/articles/1811945.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.80.-e
77.80.Fm
85.50.Gk
73.61.Ga
Opis:
In this work, we observed effects of changing the electron concentration and electron mobility upon the poling of the $Cd_{0.96}Zn_{0.04}Te$ ferroelectric gate deposited on the top of the CdTe-based modulation doped quantum well structure, which are confirmation of the existence of the electrostatic field originating from the ferroelectric material, which can be controlled by an external voltage. The analysis of the data obtained from the Hall effect measurements showed that the electron mobility and carrier concentration decreased by a factor of 2.5 and 1.5, respectively upon the negative poling of the gate with respect to the poled by the positive voltage. Moreover, the electrostatic field, depending on its directions, causes depletion of accumulation of electrons in the 2D channel, i.e., it is a source of the field effect.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1173-1178
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bychkov-Rashba Effect and g-Factor Tuning in Modulation Doped SiGe Quantum Wells
Autorzy:
Malissa, H.
Jantsch, W.
Mühlberger, M.
Schäffler, F.
Wilamowski, Z.
Draxler, M.
Bauer, P.
Powiązania:
https://bibliotekanauki.pl/articles/2038126.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Fg
85.75.-d
Opis:
We investigate the spin resonance of electrons in one-sided modulation doped Si$\text{}_{1-x}$Ge$\text{}_{x}$ (x=0-10%)) quantum wells defined by Si$\text{}_{0.75}$Ge$\text{}_{0.25}$ barriers. In such structures, the Bychkov-Rashba effect induces an effective magnetic field in the quantum well layer which causes anisotropy of both the g-factor and the spin coherence time. Evaluation of the Rashba coefficient as a function of x yields a monotonic increase. For x=5% the shift in the resonance field exceeds the ESR linewidth already, demonstrating the possibility to use this effect for g-factor tuning to select individual spins in an ensemble.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 585-590
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 30

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