Frequency Shift

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Carlos Cabrelli - One of the best experts on this subject based on the ideXlab platform.

Götz E. Pfander - One of the best experts on this subject based on the ideXlab platform.

Ursula Molter - One of the best experts on this subject based on the ideXlab platform.

Zofia Bialynicka-birula - One of the best experts on this subject based on the ideXlab platform.

  • Dynamical rotational Frequency Shift
    arXiv: Quantum Physics, 2011
    Co-Authors: Iwo Bialynicki-birula, Zofia Bialynicka-birula
    Abstract:

    The term rotational Frequency Shift (RFS) has been used in different contexts and it was given different meanings. Other terms have also been used (azimuthal Doppler Shift, angular Doppler Shift) to describe various related phenomena. In this article we stick to the meaning of the rotational Frequency Shift given by us in Phys. Rev. Lett.78, 2539 (1977). In order to make a clear distinction between our RFS and other related Shifts we use the term dynamical RFS (DRFS). We will study the spectral properties of radiation emitted by rotating quantum sources.

  • Rotational Frequency Shift
    Physical Review Letters, 1997
    Co-Authors: Iwo Bialynicki-birula, Zofia Bialynicka-birula
    Abstract:

    The notion of the rotational Frequency Shift, an analog of the Doppler Shift, is introduced. This new Frequency Shift occurs for atomic systems that lack rotational invariance, but have stationary states in a rotating frame. The rotational Frequency Shift is given by the scalar product of the angular velocity and the angular momentum of the emitted photon in full analogy with the standard Doppler Shift which is given by the scalar product of the linear velocity of the source and the linear momentum of the photon. The rotational Frequency Shift can be observed only in a Mossbauer-like regime when the angular recoil is negligible. [S0031-9007(97)02782-8] The purpose of this Letter is to describe a new effect: the Frequency Shift of emitted (or absorbed) photons that is due to the rotation of the radiating system. This rotational Frequency Shift (RFS) is a close analog of the standard, first-order Doppler Shift (the latter might be called a translational Frequency Shift) but there are two important differences. First, the dynamical laws are invariant under a uniform translation, but they are not invariant under a uniform rotation. Therefore, the differences between the energy levels are not changed by a uniform translation but they are dynamically modified by a uniform rotation, owing to the centrifugal and Coriolis forces. Hence, the Frequency of a photon emitted (absorbed) by a system moving with constant velocity is modified only by the Doppler Shift, while in the case of a rotating system the photon Frequency is modified both by the changes in the energy levels and by the RFS. For rotationally invariant systems, these two effects completely cancel each other as a result of the conservation of angular momentum, and the observed photon Frequency is unchanged, as one would have anticipated. Second, under normal conditions the recoil corrections are much more significant for the RFS than for the Doppler Shift. In order to observe the RFS one must work in a Mossbauer-like regime. The atomic system must be embedded in a larger structure that will provide the angular momentum of the emitted photon. The RFS should not be confused with the ordinary linear Doppler Shift observed for rotating objects (for example, stars or galaxies) that is due to the instantaneous linear motion of the emitter. This linear Doppler Shift is maximal in the plane of rotation while the RFS is maximal along the angular velocity, that is in the direction perpendicular to the instantaneous velocity. Thus the RFS competes with the quadratic Doppler Shift rather than with the linear Doppler Shift. Our discussion will be based on the nonrelativistic Schrodinger equation for the atomic system with a time dependent Hamiltonian. The photon emission will be treated in the first order of perturbation theory. Our derivation of the RFS will be done in parallel with the calculation of the standard Doppler Shift in order to exhibit their similarities and differences. As a generic model of a radiating system we shall consider an electron bound by a potential V std and interacting via minimal coupling with the quantized electromagnetic field. We assume that the time dependence of the potential is of the form V std › V srstddd. For a uniform translation and a uniform rotation, rstd is given by

Martin Rochette - One of the best experts on this subject based on the ideXlab platform.

  • mid infrared sources based on the soliton self Frequency Shift
    Journal of The Optical Society of America B-optical Physics, 2012
    Co-Authors: Alaa Alkadry, Martin Rochette
    Abstract:

    We present a method to maximize the soliton self-Frequency Shift (SSFS) in microwires with diameter profiles varying nonuniformly along the soliton propagation path. The method is divided into two steps. The first step consists in selecting the input microwire diameter that leads to the highest rate of Frequency Shift per unit of propagation length. The second step consists in increasing gradually the microwire diameter along the soliton path to suppress dispersive wave emission and maintain a large rate of Frequency Shift per unit of propagation length. We first propose and apply a rule to select the initial diameter using the adiabatic theory. The optimal diameter profile is then achieved by maintaining the redShifting soliton at a fixed spectral separation from the zero-dispersion wavelengths. The optimized profile supports solitons with different input energies that allow a wavelength Shift up to 650 nm from the 2100 nm pump wavelength in a 20 cm microwire length. We compare our results with the SSFS generated in microwires with uniform diameter profile to illustrate the enhancement of wavelength Shift in the designed nonuniform microwire.

  • mid infrared sources based on the soliton self Frequency Shift
    Photonics North, 2011
    Co-Authors: Alaa Alkadry, Martin Rochette
    Abstract:

    We present a method to maximize the soliton self-Frequency Shift (SSFS) in microwires with diameter profiles varying nonuniformly along the soliton propagation path. The method is divided into two steps. The first step consists in selecting the input microwire diameter that leads to the highest rate of Frequency Shift per unit of propagation length. The second step consists in increasing gradually the microwire diameter along the soliton path to suppress dispersive wave emission and maintain a large rate of Frequency Shift per unit of propagation length. We first propose and apply a rule to select the initial diameter using the adiabatic theory. The optimal diameter profile is then achieved by maintaining the redShifting soliton at a fixed spectral separation from the zero-dispersion wavelengths. The optimized profile supports solitons with different input energies that allow a wavelength Shift up to 650 nm from the 2100 nm pump wavelength in a 20 cm microwire length. We compare our results with the SSFS generated in microwires with uniform diameter profile to illustrate the enhancement of wavelength Shift in the designed nonuniform microwire. © 2012 Optical Society of America OCIS codes: 060.2310, 060.2280, 060.4370.

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