| Keynote 6 | Semiconductor Acoustic Lasers (Sasers) for Terahertz Acoustics |
| Date/Time | Friday, 3 May 2013 / 10:10 – 10:50 |
| Venue | Riverfront Ballroom |
Dr. Boris A. Glavin
V. E. Lashkaryov Institute of Semiconductor Physics
Prospekt Nauki 41, Kyiv, 03028, Ukraine
Biography :: Education, Degrees:
Kiev State University 1993– MS in Radiophysics and Electronics
Institute of Semiconductor Physics 1998–Ph.D. in Solid State Physics
Scientific Employment: April, 2001 – present: Senior research associate, V. E. Lashkarrev Institute of Semiconductor
Physics (ISP);
May, 1999 – April, 2001: Research associate, ISP;
August, 1993 – May, 1999: Engineer-researcher, ISP.
Awards:
- Felowship of the Institute of Semiconductor Physics, Frankfurt (Oder), Germany, 2000.
- Young author best paper award of IUPAP and Program Committee of the 24-th International Conference on Physics of Semiconductors, 1998.
- Fellowship of the National Academy of Sciences of Ukraine for young scientists, 1998.
- Thomas Rumble Graduate Fellowship, Wayne State University, 1996.
Field of Interest:
- Phonon lasers (sasers)
- Ultrafast acoustics, acousto-electronics, magneto-acoustics, and acousto-optics.
- Electron-phonon interaction in semiconductor nanostructures.
- Phonon transport in nanostructures.
- Spin relaxation phenomena in solids.
- Resonant tunneling.
- Kinetics of highly nonequilibrium electrons and phonons.
Visits, Collaboration:
- University of Nottingham;
- University of Dortmund;
- International Centre for Theoretical Physics;
- North Carolina State University;
- Wayne State University.
Abstract
The talk outlines recently achieved progress in development of devices with stimulated emission of terahertz
acoustic phonons (sasers) – an acoustic analog of optical lasers. Such phonons has wavelength about ten
nanometers. If developed for a proper level, sasers could change essentially the solid-state acoustics with especial
effect in studies of nanostructures. Themost extensively studied saser structure is formed by semiconductor
(GaAs/AlAs) multi-layers of few-nanometer thickness. Active part of the saser is a doped superlattice. Under
the proper structure design, electron population inversion with respect to phonon-assisted inter-well electron
transitions under application of electrical bias is created. Such an inversion is present for longitudinal phonons
propagating close to the superlattice axis and belonging to relatively narrow spectral band tunable by variation
of the bias. The other component of the saser structure “the phonon cavity” is formed by acoustic Bragg mirrors
or the sample surface confining the phonon modes inside the Fabry-Perot cavity. We present experimental
evidences of the saser operation under different conditions. This includes measurement of the phonon amplification
in cavity-less samples using bolometric or pump-probe technique; observation of the steady-state saser emission; studies of the saser dynamics under transient pumping. We have found that the single-pass amplification
through 50-period superlattice can be as high as 20%, and acoustic radiation built-up time is about 1
ns. Another important finding supported by theoretical analysis is robust character of the acoustic amplification
against the structure disorder inevitable under the growth process. Results for alternative saser structures
based on undoped superlattices with optical pumping capable of terahertz transverse wave emission are also
discussed.
