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Coherent phonon optics in a chip with an electrically controlled active device.

Poyser CL, Akimov AV, Campion RP, Kent AJ - Sci Rep (2015)

Bottom Line: Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path.In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer.Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.

ABSTRACT
Phonon optics concerns operations with high-frequency acoustic waves in solid media in a similar way to how traditional optics operates with the light beams (i.e. photons). Phonon optics experiments with coherent terahertz and sub-terahertz phonons promise a revolution in various technical applications related to high-frequency acoustics, imaging, and heat transport. Previously, phonon optics used passive methods for manipulations with propagating phonon beams that did not enable their external control. Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path. In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer. Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale.

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Phonon optics with passive phononic chip.(a) Temporal evolution of the detected signal which accompanies the coherent phonon wavepacket in the p-i-n detector for V = 0. Sharp peaks, marked by dotted lines, correspond to the strain pulses generated at various interfaces in the phononic chip (the lower inset shows the paths corresponding to the three high amplitude peaks labeled t0tc and tR). The signal possesses harmonic oscillations with f0 = 378 GHz (see the zoomed fragment on the upper inset). The dashed rectangle indicates the time interval where harmonic oscillations have maximum amplitude. (b) Fast Fourier Transform of the signal shown in (a) obtained in full time window from −0.3 ns up to 0.5 ns. The sharp peaks and f0 and f1 correspond to the coherent monochromatic phonons generated by optical pump pulses in the transducer and active SLs respectively.
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f2: Phonon optics with passive phononic chip.(a) Temporal evolution of the detected signal which accompanies the coherent phonon wavepacket in the p-i-n detector for V = 0. Sharp peaks, marked by dotted lines, correspond to the strain pulses generated at various interfaces in the phononic chip (the lower inset shows the paths corresponding to the three high amplitude peaks labeled t0tc and tR). The signal possesses harmonic oscillations with f0 = 378 GHz (see the zoomed fragment on the upper inset). The dashed rectangle indicates the time interval where harmonic oscillations have maximum amplitude. (b) Fast Fourier Transform of the signal shown in (a) obtained in full time window from −0.3 ns up to 0.5 ns. The sharp peaks and f0 and f1 correspond to the coherent monochromatic phonons generated by optical pump pulses in the transducer and active SLs respectively.

Mentions: With no bias applied to the active SL, the experimental device can be considered to be a passive phononic chip. The temporal evolution of the strain P0(t) detected in the p-i-n for the case when the bias is not applied to the active SL (V = 0) is shown in Fig. 2a. The temporal trace P0(t) is spread over the time interval ~1 ns and includes several high-amplitude peaks and harmonic oscillations with a frequency of f0 = 378 GHz (see the zoomed fragment in Fig. 2a). The value t = 0 is defined as the arrival time of the phonons generated at the open surface of the top SL to the p-i-n detector after their ballistic propagation through the semiconductor chip with the average velocity 4.8 km/s (this path is shown by an arrow t0 in the lower inset of Fig. 2a). The fast Fourier transform (FFT) of P0(t) obtained for the full temporal interval is shown in Fig. 2b. The amplitude FFT spectrum consists of a large number of closely located spikes and two well isolated peaks at f0 = 378 GHz and f1 = 519 GHz with the widths 2 and 10 GHz respectively indicated in Fig. 2b by the vertical arrows. The temporal shape of P0(t) and its spectrum are in agreement with the earlier results in phonon optics experiments with passive SL devices2145. The most important feature is the existence of the essential contribution from monochromatic phonons with the frequency f0 = 378 GHz that is attributed to coherent phonon generation in the transducer SL as a result of pump optical excitation.


Coherent phonon optics in a chip with an electrically controlled active device.

Poyser CL, Akimov AV, Campion RP, Kent AJ - Sci Rep (2015)

Phonon optics with passive phononic chip.(a) Temporal evolution of the detected signal which accompanies the coherent phonon wavepacket in the p-i-n detector for V = 0. Sharp peaks, marked by dotted lines, correspond to the strain pulses generated at various interfaces in the phononic chip (the lower inset shows the paths corresponding to the three high amplitude peaks labeled t0tc and tR). The signal possesses harmonic oscillations with f0 = 378 GHz (see the zoomed fragment on the upper inset). The dashed rectangle indicates the time interval where harmonic oscillations have maximum amplitude. (b) Fast Fourier Transform of the signal shown in (a) obtained in full time window from −0.3 ns up to 0.5 ns. The sharp peaks and f0 and f1 correspond to the coherent monochromatic phonons generated by optical pump pulses in the transducer and active SLs respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4317685&req=5

f2: Phonon optics with passive phononic chip.(a) Temporal evolution of the detected signal which accompanies the coherent phonon wavepacket in the p-i-n detector for V = 0. Sharp peaks, marked by dotted lines, correspond to the strain pulses generated at various interfaces in the phononic chip (the lower inset shows the paths corresponding to the three high amplitude peaks labeled t0tc and tR). The signal possesses harmonic oscillations with f0 = 378 GHz (see the zoomed fragment on the upper inset). The dashed rectangle indicates the time interval where harmonic oscillations have maximum amplitude. (b) Fast Fourier Transform of the signal shown in (a) obtained in full time window from −0.3 ns up to 0.5 ns. The sharp peaks and f0 and f1 correspond to the coherent monochromatic phonons generated by optical pump pulses in the transducer and active SLs respectively.
Mentions: With no bias applied to the active SL, the experimental device can be considered to be a passive phononic chip. The temporal evolution of the strain P0(t) detected in the p-i-n for the case when the bias is not applied to the active SL (V = 0) is shown in Fig. 2a. The temporal trace P0(t) is spread over the time interval ~1 ns and includes several high-amplitude peaks and harmonic oscillations with a frequency of f0 = 378 GHz (see the zoomed fragment in Fig. 2a). The value t = 0 is defined as the arrival time of the phonons generated at the open surface of the top SL to the p-i-n detector after their ballistic propagation through the semiconductor chip with the average velocity 4.8 km/s (this path is shown by an arrow t0 in the lower inset of Fig. 2a). The fast Fourier transform (FFT) of P0(t) obtained for the full temporal interval is shown in Fig. 2b. The amplitude FFT spectrum consists of a large number of closely located spikes and two well isolated peaks at f0 = 378 GHz and f1 = 519 GHz with the widths 2 and 10 GHz respectively indicated in Fig. 2b by the vertical arrows. The temporal shape of P0(t) and its spectrum are in agreement with the earlier results in phonon optics experiments with passive SL devices2145. The most important feature is the existence of the essential contribution from monochromatic phonons with the frequency f0 = 378 GHz that is attributed to coherent phonon generation in the transducer SL as a result of pump optical excitation.

Bottom Line: Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path.In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer.Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.

ABSTRACT
Phonon optics concerns operations with high-frequency acoustic waves in solid media in a similar way to how traditional optics operates with the light beams (i.e. photons). Phonon optics experiments with coherent terahertz and sub-terahertz phonons promise a revolution in various technical applications related to high-frequency acoustics, imaging, and heat transport. Previously, phonon optics used passive methods for manipulations with propagating phonon beams that did not enable their external control. Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path. In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer. Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale.

No MeSH data available.


Related in: MedlinePlus