A source of terahertz coherent phonons

Makler, S. S.; Vasilevskiy, Mikhail; Anda, E. V.; Tuyarot, Diana E.; Weberszpil, José; Pastawski, Horacio M.

doi:10.1088/0953-8984/10/26/017

Cited by 23 publications

(27 citation statements)

References 51 publications

(68 reference statements)

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“…Different methods of coherent THz phonon generation (and amplification) have been suggested [15,16], but no turn-key THz acoustic analogue of the laser has been developed to date. However, previous studies of acoustic gain in semiconductor SLs have been made both theoretically [17,18] and experimentally [12], which have shown great promise for THz phonon amplification and oscillation in these systems.…”

Section: Introductionmentioning

confidence: 99%

A GaAs/AlAs superlattice as an electrically pumped THz acoustic phonon amplifier

et al. 2011

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Abstract. In a semiconductor superlattice (SL), phonon-assisted electron transitions can occur under a quasi-population inversion, brought about by electrical biasing. This paper demonstrates the amplification of an optically excited quasi-monochromatic phonon beam by stimulated emission of phonons. Coherent phonons are generated by ultrafast optical excitation of a generator SL and passed once through a dc biased, GaAs/AlAs gain SL. A 20% increase in the phonon flux is detected when pumping is applied to the gain superlattice, which corresponds to an acoustic gain coefficient of 3600 cm −1 . A theoretical model of the phonon amplification is presented that also includes the effects of disorder in the SL. It is found that the amplification process is robust in the presence of disorder and good agreement is obtained with the main features of the experimental observations.

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Section: Introductionmentioning

confidence: 99%

A GaAs/AlAs superlattice as an electrically pumped THz acoustic phonon amplifier

et al. 2011

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“…In these RTDs even when the LO phonons are confined to the well, they have a short lifetime [11] because they decay into a pair of LO and transverse acoustic (TA) phonons. The expectation that the secondary TA phonons can form a coherent beam inspired a proposal for the generation of a coherent sound beam (in the region of 2 THz) which justifies the name of SASER in analogy with LASER [12,13] for such device. The critical intensities required for stimulated decay of the primary phonons were recently discussed [14].…”

Section: Introductionmentioning

confidence: 99%

“…The devices considered previously in this context Refs. [13,15] required an energy difference between the first two electronic states in the well satisfying the resonant condition E 1 2 E 0 ¼ Év 0 (see Fig. 1(b)).…”

Section: Introductionmentioning

confidence: 99%

An ultrasound emitter based on assisted tunneling

Torres

Pastawski

Makler

2002

Solid State Communications

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The problem of electron tunneling assisted by an elementary excitation in a double barrier resonant device is usually described within a sequential (decoherent) approximation. By solving exactly the many-body problem for a simplified model of electron -phonon interaction we show, analytically and numerically, that the assisted tunneling peak can be strongly enhanced by an appropriate election of the geometrical parameters of the device. This induces a symmetry condition in the Fock space that maximizes the effectiveness of the scattering process. We propose that this process could provide the primary longitudinal optical phonons required to operate a phonon laser (SASER). q

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“…1); optomechanical devices at megahertz frequencies2; optically pumped trapped ions at very low frequencies3; and acoustic amplification at about half a THz, due to electron–phonon interactions in semiconductor superlattices (SLs)45. The latter is particularly important as it addresses the generation of coherent acoustic waves in the THz frequency range with corresponding acoustic wavelengths in the nanometre range, useful in a number of applications6.…”

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confidence: 99%

Dynamics of a vertical cavity quantum cascade phonon laser structure

et al. 2013

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Driven primarily by scientific curiosity, but also by the potential applications of intense sources of coherent sound, researchers have targeted the phonon laser (saser) since the invention of the optical laser over 50 years ago. Here we fabricate a vertical cavity structure designed to operate as a saser oscillator device at a frequency of 325 GHz. It is based on a semiconductor superlattice gain medium, inside a multimode cavity between two acoustic Bragg reflectors. We measure the acoustic output of the device as a function of time after applying electrical pumping. The emission builds in intensity reaching a steady state on a timescale of order 0.1 μs. We show that the results are consistent with a model of the dynamics of a saser cavity exactly analogous to the models used for describing laser dynamics. We also obtain estimates for the gain coefficient, steady-state acoustic power output and efficiency of the device.

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A source of terahertz coherent phonons

Cited by 23 publications

References 51 publications

A GaAs/AlAs superlattice as an electrically pumped THz acoustic phonon amplifier

A GaAs/AlAs superlattice as an electrically pumped THz acoustic phonon amplifier

An ultrasound emitter based on assisted tunneling

Dynamics of a vertical cavity quantum cascade phonon laser structure

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