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.


Field of Interest:

Visits, Collaboration:

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.