The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform

Juan C Cervantesgonzalez - One of the best experts on this subject based on the ideXlab platform.

  • reflection and transmission of a wave incident on a slab with a time periodic dielectric function epsilon t
    Physical Review A, 2009
    Co-Authors: Jorge R Zuritasanchez, P. Halevi, Juan C Cervantesgonzalez
    Abstract:

    We present a theoretical description of the response of a dynamic slab, with time-periodic dielectric function {epsilon}(t), to a normally incident monochromatic plane wave of Frequency {omega}{sub o}. As a consequence of the interaction of this incoming wave with the dynamic slab, the reflected and transmitted waves contain harmonics of the Modulating Frequency {omega}, namely, the slab itself becomes a polychromatic source of frequencies {omega}{sub o}-n{omega}(n=0,{+-}1,{+-}2,...). We establish a general formalism to quantify the reflected and transmitted fields for any periodic variation in the dielectric function. To achieve this, a description of wave propagation in a dynamic bulk is needed. A theoretical framework to treat such propagation, based on the concept of a temporal photonic crystal, is developed. As a consequence of the Bloch-Floquet theorem, the dispersion relation is a band structure that is periodic with Frequency and exhibits forbidden wave vector gaps. The Poynting vectors of the transmitted and reflected fields are analyzed in detail. Our theory is applied to the case in which the dielectric function is modulated sinusoidally. We calculate numerically the magnitudes and phases of the reflection and transmission coefficients for several harmonics {omega}{sub o}-n{omega} and slab thicknesses. Three modulation regimes are considered: weak, moderate, andmore » strong. The response in the weak regime is similar to that of a Fabry-Perot etalon--the strengths of the harmonics are weak. For the strong-modulation regime, the strengths of reflection and transmission coefficients of the harmonics become large; they can even exceed one due to the openness of the system in which an external Modulating agent can provide part of the invested energy. Dynamic variation in the dielectric properties of materials can give rise to new effects in wave propagation and to novel optical applications and is readily attainable with present-day technology.« less

  • reflection and transmission of a wave incident on a slab with a time periodic dielectric function epsilon t
    Physical Review A, 2009
    Co-Authors: Jorge R Zuritasanchez, P. Halevi, Juan C Cervantesgonzalez
    Abstract:

    We present a theoretical description of the response of a dynamic slab, with time-periodic dielectric function $ϵ(t)$, to a normally incident monochromatic plane wave of Frequency ${\ensuremath{\omega}}_{o}$. As a consequence of the interaction of this incoming wave with the dynamic slab, the reflected and transmitted waves contain harmonics of the Modulating Frequency $\ensuremath{\Omega}$, namely, the slab itself becomes a polychromatic source of frequencies ${\ensuremath{\omega}}_{o}\ensuremath{-}n\ensuremath{\Omega}(n=0,\ifmmode\pm\else\textpm\fi{}1,\ifmmode\pm\else\textpm\fi{}2,\dots{})$. We establish a general formalism to quantify the reflected and transmitted fields for any periodic variation in the dielectric function. To achieve this, a description of wave propagation in a dynamic bulk is needed. A theoretical framework to treat such propagation, based on the concept of a temporal photonic crystal, is developed. As a consequence of the Bloch-Floquet theorem, the dispersion relation is a band structure that is periodic with Frequency and exhibits forbidden wave vector gaps. The Poynting vectors of the transmitted and reflected fields are analyzed in detail. Our theory is applied to the case in which the dielectric function is modulated sinusoidally. We calculate numerically the magnitudes and phases of the reflection and transmission coefficients for several harmonics ${\ensuremath{\omega}}_{o}\ensuremath{-}n\ensuremath{\Omega}$ and slab thicknesses. Three modulation regimes are considered: weak, moderate, and strong. The response in the weak regime is similar to that of a Fabry-Perot etalon---the strengths of the harmonics are weak. For the strong-modulation regime, the strengths of reflection and transmission coefficients of the harmonics become large; they can even exceed one due to the openness of the system in which an external Modulating agent can provide part of the invested energy. Dynamic variation in the dielectric properties of materials can give rise to new effects in wave propagation and to novel optical applications and is readily attainable with present-day technology.

Jorge R Zuritasanchez - One of the best experts on this subject based on the ideXlab platform.

  • reflection and transmission of a wave incident on a slab with a time periodic dielectric function epsilon t
    Physical Review A, 2009
    Co-Authors: Jorge R Zuritasanchez, P. Halevi, Juan C Cervantesgonzalez
    Abstract:

    We present a theoretical description of the response of a dynamic slab, with time-periodic dielectric function {epsilon}(t), to a normally incident monochromatic plane wave of Frequency {omega}{sub o}. As a consequence of the interaction of this incoming wave with the dynamic slab, the reflected and transmitted waves contain harmonics of the Modulating Frequency {omega}, namely, the slab itself becomes a polychromatic source of frequencies {omega}{sub o}-n{omega}(n=0,{+-}1,{+-}2,...). We establish a general formalism to quantify the reflected and transmitted fields for any periodic variation in the dielectric function. To achieve this, a description of wave propagation in a dynamic bulk is needed. A theoretical framework to treat such propagation, based on the concept of a temporal photonic crystal, is developed. As a consequence of the Bloch-Floquet theorem, the dispersion relation is a band structure that is periodic with Frequency and exhibits forbidden wave vector gaps. The Poynting vectors of the transmitted and reflected fields are analyzed in detail. Our theory is applied to the case in which the dielectric function is modulated sinusoidally. We calculate numerically the magnitudes and phases of the reflection and transmission coefficients for several harmonics {omega}{sub o}-n{omega} and slab thicknesses. Three modulation regimes are considered: weak, moderate, andmore » strong. The response in the weak regime is similar to that of a Fabry-Perot etalon--the strengths of the harmonics are weak. For the strong-modulation regime, the strengths of reflection and transmission coefficients of the harmonics become large; they can even exceed one due to the openness of the system in which an external Modulating agent can provide part of the invested energy. Dynamic variation in the dielectric properties of materials can give rise to new effects in wave propagation and to novel optical applications and is readily attainable with present-day technology.« less

  • reflection and transmission of a wave incident on a slab with a time periodic dielectric function epsilon t
    Physical Review A, 2009
    Co-Authors: Jorge R Zuritasanchez, P. Halevi, Juan C Cervantesgonzalez
    Abstract:

    We present a theoretical description of the response of a dynamic slab, with time-periodic dielectric function $ϵ(t)$, to a normally incident monochromatic plane wave of Frequency ${\ensuremath{\omega}}_{o}$. As a consequence of the interaction of this incoming wave with the dynamic slab, the reflected and transmitted waves contain harmonics of the Modulating Frequency $\ensuremath{\Omega}$, namely, the slab itself becomes a polychromatic source of frequencies ${\ensuremath{\omega}}_{o}\ensuremath{-}n\ensuremath{\Omega}(n=0,\ifmmode\pm\else\textpm\fi{}1,\ifmmode\pm\else\textpm\fi{}2,\dots{})$. We establish a general formalism to quantify the reflected and transmitted fields for any periodic variation in the dielectric function. To achieve this, a description of wave propagation in a dynamic bulk is needed. A theoretical framework to treat such propagation, based on the concept of a temporal photonic crystal, is developed. As a consequence of the Bloch-Floquet theorem, the dispersion relation is a band structure that is periodic with Frequency and exhibits forbidden wave vector gaps. The Poynting vectors of the transmitted and reflected fields are analyzed in detail. Our theory is applied to the case in which the dielectric function is modulated sinusoidally. We calculate numerically the magnitudes and phases of the reflection and transmission coefficients for several harmonics ${\ensuremath{\omega}}_{o}\ensuremath{-}n\ensuremath{\Omega}$ and slab thicknesses. Three modulation regimes are considered: weak, moderate, and strong. The response in the weak regime is similar to that of a Fabry-Perot etalon---the strengths of the harmonics are weak. For the strong-modulation regime, the strengths of reflection and transmission coefficients of the harmonics become large; they can even exceed one due to the openness of the system in which an external Modulating agent can provide part of the invested energy. Dynamic variation in the dielectric properties of materials can give rise to new effects in wave propagation and to novel optical applications and is readily attainable with present-day technology.

B.b. Pal - One of the best experts on this subject based on the ideXlab platform.

  • Effect of surface recombination and modulated Frequency on the intrinsic parameters of an ion-implanted GaAs OPFET
    Conference on Physics and Technology of Semiconductor Devices and Integrated Circuits, 1992
    Co-Authors: Vinaya Kumar Singh, S R Singh, B.b. Pal
    Abstract:

    The effect of surface recombination and modulated Frequency on the intrinsic parameters of an ion implanted GaAs optical field effect transistor have been analyzed. The study reveals that the gate-source capacitance increases with gate-source voltage, first slowly, and then sharply under normally OFF condition with the increase of modulated Frequency. However, the surface recombination reduces these effects depending upon the trap center density. These variations are small in a normally ON device. Also, the drain-source resistance is found to increase with the increase of Modulating Frequency, but it reduces with the reduction of trap- center density at a fixed flux density and drain-source voltage.

  • Surface recombination and carrier-Frequency-dependent intrinsic parameters of an ion-implanted GaAs OPFET
    Semiconductor Science and Technology, 1991
    Co-Authors: Vinaya Kumar Singh, S R Singh, B.b. Pal
    Abstract:

    Surface recombination and carrier-Frequency-dependent intrinsic parameters of an ion-implanted GaAs optical field effect transistor RF switch have been analysed. The study reveals that the gate-source capacitance increases with gate-source voltage, at first slowly and then sharply under enhancement mode with an increase of Modulating Frequency. however, surface recombination reduces these effects depending upon the trap centre density. The surface recombination effect becomes significant only when the trap centre density is nearly equal to or greater than 1022 m-2. These variations are small in depletion devices. The drain-source resistance is found to increase with increasing Modulating Frequency, but it decreases with the reduction of trap centre density at a fixed flux density and drain-source voltage. It is also observed that the RC time constant increases significantly with gate length and reduces with increase of trap centre density at a fixed radiation flux density, Modulating Frequency and drain-source voltage.

Weidong Hu - One of the best experts on this subject based on the ideXlab platform.

  • synthetic aperture radar target feature transformation method based on random code phase switched screen
    IEEE Access, 2018
    Co-Authors: Junjie Wang, Letao Xu, Dejun Feng, Qihua Wu, Weidong Hu
    Abstract:

    As a novel passive device, phase-switched screen (PSS) imposes phase modulation onto the radar signal and has been extensively applied in radar target stealth. Recently, the blanket jamming method based on PSS is proposed against synthetic aperture radar (SAR). However, the method still remains challenging to obtain the desired jamming effect because it suffers from insufficient energy when the reflectivity of the reflector is not enough or the protected area is too large. In this paper, a target feature transformation method based on PSS is proposed to counter SAR. The method attaches the PSS material to the protected target surface and utilizes one-dimensional (1-D) or two-dimensional (2-D) random code PSS modulation to dynamically control the reflected signal. As a result, the generated target image is defocused and turned into some strip-shaped or square-shaped areas when modulated signal is received and processed by the victim radar system. The target feature is transformed greatly and cannot be detected by radar. Moreover, the shape of the generated area can be flexibly controlled by the code width and inter-pulse Modulating Frequency. Simulations and experimental results are utilized to verify the effectiveness of the proposed method.

P. Halevi - One of the best experts on this subject based on the ideXlab platform.

  • reflection and transmission of a wave incident on a slab with a time periodic dielectric function epsilon t
    Physical Review A, 2009
    Co-Authors: Jorge R Zuritasanchez, P. Halevi, Juan C Cervantesgonzalez
    Abstract:

    We present a theoretical description of the response of a dynamic slab, with time-periodic dielectric function {epsilon}(t), to a normally incident monochromatic plane wave of Frequency {omega}{sub o}. As a consequence of the interaction of this incoming wave with the dynamic slab, the reflected and transmitted waves contain harmonics of the Modulating Frequency {omega}, namely, the slab itself becomes a polychromatic source of frequencies {omega}{sub o}-n{omega}(n=0,{+-}1,{+-}2,...). We establish a general formalism to quantify the reflected and transmitted fields for any periodic variation in the dielectric function. To achieve this, a description of wave propagation in a dynamic bulk is needed. A theoretical framework to treat such propagation, based on the concept of a temporal photonic crystal, is developed. As a consequence of the Bloch-Floquet theorem, the dispersion relation is a band structure that is periodic with Frequency and exhibits forbidden wave vector gaps. The Poynting vectors of the transmitted and reflected fields are analyzed in detail. Our theory is applied to the case in which the dielectric function is modulated sinusoidally. We calculate numerically the magnitudes and phases of the reflection and transmission coefficients for several harmonics {omega}{sub o}-n{omega} and slab thicknesses. Three modulation regimes are considered: weak, moderate, andmore » strong. The response in the weak regime is similar to that of a Fabry-Perot etalon--the strengths of the harmonics are weak. For the strong-modulation regime, the strengths of reflection and transmission coefficients of the harmonics become large; they can even exceed one due to the openness of the system in which an external Modulating agent can provide part of the invested energy. Dynamic variation in the dielectric properties of materials can give rise to new effects in wave propagation and to novel optical applications and is readily attainable with present-day technology.« less

  • reflection and transmission of a wave incident on a slab with a time periodic dielectric function epsilon t
    Physical Review A, 2009
    Co-Authors: Jorge R Zuritasanchez, P. Halevi, Juan C Cervantesgonzalez
    Abstract:

    We present a theoretical description of the response of a dynamic slab, with time-periodic dielectric function $ϵ(t)$, to a normally incident monochromatic plane wave of Frequency ${\ensuremath{\omega}}_{o}$. As a consequence of the interaction of this incoming wave with the dynamic slab, the reflected and transmitted waves contain harmonics of the Modulating Frequency $\ensuremath{\Omega}$, namely, the slab itself becomes a polychromatic source of frequencies ${\ensuremath{\omega}}_{o}\ensuremath{-}n\ensuremath{\Omega}(n=0,\ifmmode\pm\else\textpm\fi{}1,\ifmmode\pm\else\textpm\fi{}2,\dots{})$. We establish a general formalism to quantify the reflected and transmitted fields for any periodic variation in the dielectric function. To achieve this, a description of wave propagation in a dynamic bulk is needed. A theoretical framework to treat such propagation, based on the concept of a temporal photonic crystal, is developed. As a consequence of the Bloch-Floquet theorem, the dispersion relation is a band structure that is periodic with Frequency and exhibits forbidden wave vector gaps. The Poynting vectors of the transmitted and reflected fields are analyzed in detail. Our theory is applied to the case in which the dielectric function is modulated sinusoidally. We calculate numerically the magnitudes and phases of the reflection and transmission coefficients for several harmonics ${\ensuremath{\omega}}_{o}\ensuremath{-}n\ensuremath{\Omega}$ and slab thicknesses. Three modulation regimes are considered: weak, moderate, and strong. The response in the weak regime is similar to that of a Fabry-Perot etalon---the strengths of the harmonics are weak. For the strong-modulation regime, the strengths of reflection and transmission coefficients of the harmonics become large; they can even exceed one due to the openness of the system in which an external Modulating agent can provide part of the invested energy. Dynamic variation in the dielectric properties of materials can give rise to new effects in wave propagation and to novel optical applications and is readily attainable with present-day technology.