The effect of the quantum nature of excitons on the phonoriton states in semiconductors

Khue, Nguyen Minh; Huong, Nguyen Que; Quang, Nguyễn Hồng

doi:10.1088/0953-8984/6/17/011

Cited by 4 publications

(5 citation statements)

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“…This dynamical renormalization of the spectrum relates to the phonoriton transient excitations of a semiconductor in the presence of the given intense coherent polariton. [11][12][13][14][15][16] The phonoriton dispersion follows dynamically the optical pump intensity and gives rise to the phonon-mediated exciton optical Stark effect. 12 However, for the Raman TWS's the renormalized dispersion is even more complicated than that of the phonoriton, because the two coupled nonlinear polaritons have comparable intensities.…”

Section: Introductionmentioning

confidence: 99%

“…Then, the second polariton is a given coherent pump wave with the polarization P 2 ϭ P 02 exp(Ϫi k tϩik) and Eqs. ͑4a͒-͑4c͒ describe the phonoriton excitations [11][12][13][14][15][16] of a semiconductor. The phonoriton dispersion, i.e., the dynamical coherent photon-exciton-LO-phonon spectrum, develops in the spectral vicinity of the anti-Stokes resonance k ϩ⍀ 0 of the pump polariton 2.…”

Section: Introductionmentioning

confidence: 99%

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Coupled solitons in resonant Raman interaction of intense polaritons

Ivanov¹,

Haug²,

Vygovskii³

1996

Phys. Rev. B

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The generation of three-wave solitons ͑TWS's͒ in the resonant LO-phonon -mediated interaction of two intense coherent polaritons is proposed and analyzed. These TWS's consist of the mutually coupled two polariton and LO-phonon nonlinear waves and propagate without dispersive spreading with an anomalous soliton velocity. Starting with an initial microscopic picture of the exciton -LO-phonon Fröhlich interaction and exciton-photon polariton coupling in polar direct-band-gap semiconductors, we derive a closed set of five macroscopic equations for a resonant triplet: polariton 1 -polariton 2 -LO phonon. An adequate method of finding the fundamental TWS's of these nonlinear equations is developed. This approach treats the LO-phonon -mediated polariton-polariton interaction beyond the standard perturbation theory, which deals with the lowest nonlinear susceptibilities (2) and (3) . A classification of the fundamental Raman solitons by their dispersion is given in terms of quasipolariton and quasiphonon TWS's. For the quasipolariton TWS's, one of the mutually coupled nonlinear polaritons is a giant parametric solitary pulse, the common soliton velocity v s decreases with the intensities of the polaritons. The quasiphonon Raman TWS's have no analogy in classical nonlinear optics. These coupled solitons are accompanied by a giant LO-phonon solitary pulse, and v s increases with the optical pump intensity.where B p , ␣ p , and c p are the exciton, photon, and optical phonon operators, respectively; x (p)ϭ t ϩp 2 /2M , ␥ (p)ϭcp/ͱ g , and ⍀ 0 are the corresponding dispersions; g is the background optical dielectric constant for the exciton resonance; M is the exciton translational mass; ប t is the energy of a transverse exciton. Two basic interactions, exciton-photon H x-␥ and exciton-phonon H x-ph , enter the Hamiltonian ͑1͒, which describe the exciton-photon-phonon system of a direct-band-gap semiconductor.The Hamiltonian H x-␥ of Eq. ͑1͒ describes the excitontransverse light field interaction, which follows the momentum conservation. The oscillator strength ⍀ c ͑polariton pa-rameter͒ of the exciton-photon coupling is determined by53 13 483 COUPLED SOLITONS IN RESONANT RAMAN INTERACTION . . .

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Coupled solitons in resonant Raman interaction of intense polaritons

Ivanov¹,

Haug²,

Vygovskii³

1996

Phys. Rev. B

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“…Usually, this contrasts with purely scattered, incoherent states in, e.g., Raman and Brillouin scattering of polaritons [4][5][6]. However, when pumped by an intense laser, up-conversion phonon-assisted scattering can reveal a phonoriton spectrum [7][8][9][10][11]. It is a quasilinear mode depending parametrically on the intensity of the pump light.…”

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confidence: 99%

LA Phonoritons inCu2O

et al. 1999

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We report the observation of LA-phonoriton eigenstates, which are a pump-induced coherent superposition of excitons, photons, and longitudinal acoustic (LA) phonons developing in up-conversion Brillouin scattering of an intense polariton. The excitonic component of the LA phonoritons in a Cu 2 O bulk crystal in the presence of a coherent orthoexcitonic polariton is studied by stimulated twophoton emission spectroscopy. For optical intensities of 30 200 MW͞cm 2 the relevant scale of the pump-induced spectral changes is 5 10 meV. The theory of LA phonoritons in Cu 2 O quantitatively reproduces the experimental data. 63.20.Ls Since the discovery of an exciton in Cu 2 O [1] this semiconductor became a prototype material in the physics of excitons, due to the large binding energy of the groundstate exciton and due to an extremely high quality of the naturally grown crystals. A ground-state 1S orthoexciton of the yellow series (binding energy e x Ӎ 150 meV and Bohr radius a x Ӎ 7 Å) is dipole forbidden. However, at low temperatures the quadrupole interaction between the orthoexciton and the light field leads to a weak, but still well-defined, polariton [2]. Recently, the quadrupole polaritons in Cu 2 O were finally visualized by propagation beat spectroscopy [3].The polariton is an example of a linear mode (coherent superposition of exciton and photon). Usually, this contrasts with purely scattered, incoherent states in, e.g., Raman and Brillouin scattering of polaritons [4-6]. However, when pumped by an intense laser, up-conversion phonon-assisted scattering can reveal a phonoriton spectrum [7][8][9][10][11]. It is a quasilinear mode depending parametrically on the intensity of the pump light. It characterizes a coherent superposition of exciton, photon, and phonon. The phonoriton spectrum associated with optical phonons gives rise to the phonon-mediated optical Stark effect, which has already been observed in some polymers (e.g., polydiacetylene) as well as in the inorganic semiconductors CdS and HgI 2 [12]. In this Letter we report the first observation of longitudinal acoustic (LA) phonoritons. For this purpose we study stimulated two-photon emission (STPE) from virtual excitons created by up-conversion Brillouin scattering of a high-intensity quadrupole polariton in Cu 2 O. Because of the linear dispersion of acoustic phonons the resulting dispersions are different from those of optical phonoritons. Furthermore, the thermally activated LA phonoritons contribute to STPE even at helium temperatures.The quadrupole polaritons in Cu 2 O are characterized by the dispersion equation ͑v

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“…Recently the quantum optical properties of the quasiparticles in condensed matters have been investigated intensively [1][2][3][4][5][6][7][8][9][10]. In particular, the nonclassical properties of exciton-polariton were considered in [1][2][3], phonon-polariton in [4], and squeezed states of excitons were considered in [5][6][7].…”

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confidence: 99%

“…The formulas (17)-(20) are our main results from which we would like to emphasize the followings. Since u i , v i are expressed in ǫ i , E * and g * (see (10), (11)) which in turn depend explicitly on light frequency ω , coupling constants f, λ , and the exciton density n ex (see (6)-(8)), one can expect various kinds of dependence of the exciton squeezing on these parameters.…”

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Density-Dependent Phonoriton States in Highly Excited Semiconductors

Quang

Khue²

1995

Int. J. Mod. Phys. B

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The dynamical aspects of the phonoriton state in highly-photoexcited semiconductors is studied theoretically. The effect of the exciton–exciton interaction and nonbosonic character of high-density excitons are taken into account. Using Green's function method and within the Random Phase Approximation it is shown that the phonoriton dispersion and damping are very sensitive to the exciton density, characterizing the excitation degree of semiconductors.

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The effect of the quantum nature of excitons on the phonoriton states in semiconductors

Cited by 4 publications

References 3 publications

Coupled solitons in resonant Raman interaction of intense polaritons

Coupled solitons in resonant Raman interaction of intense polaritons

LA Phonoritons inCu2O

Density-Dependent Phonoriton States in Highly Excited Semiconductors

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