15th International Conference on Phonon Scattering in Condensed Matter (Phonons 2015)
Abstract
We propose to create a new technology based on applications of sound waves in the 0.1 Ð 2 terahertz (THz) frequency range (one terahertz = one thousand billion hertz). In quantum mechanical terms, such high frequency sound waves can be described as coherent acoustic phonons, which can be generated by semiconductor quantum cascade saser, for: sound amplification by the stimulated emission of (phonon) radiation, devices [1], as well as optically. While technological applications of electrons and photons in solid materials are well established, phonons have hitherto been considered more of a nuisance, due to, for example, their role in scattering electrons. This work is about the useful exploitation of phonons. To achieve this we will carry out a programme of experimental and theoretical work, aimed at understanding the physical processes behind high frequency acoustic wave-induced optoelectronic phenomena, which will allow us then to propose several new classes of optical, high-frequency and microwave devices. These devices will offer significant performance advantages over current device concepts, including faster operation and lower energy consumption, which will enable new acousto-optoelectronic applications to be explored in communications, spectroscopy and IT. The aim of this research programme is to study THz acoustic wave-induced effects in semiconductor nanostructures, and to apply these effects in a new class of acousto-optoelectronic devices which could be operated by saser sound. These aims will be addressed by achieving the following specific objectives. We will: 1. Investigate acoustoelectric methods for generating THz frequency range electromagnetic waves, using quantum well and superlattice structures pumped with coherent acoustic waves, which will provide a greatly enhanced and controllable range of pulse durations compared with existing sources. 2. Achieve heterodyne mixing of sub-mm electromagnetic waves with THz acoustic waves, in order to develop novel THz spectroscopy and communications systems-on-a-chip, which will be both compact and low cost compared with existing systems, while providing comparable performance. 3. Demonstrate high-speed acousto-optical modulation of UV light. This will establish new principles of possible manipulation of radiation in this band, and, in view of importance of UV band for spectroscopy, could result in applications in fundamental research. 4. Investigate structures for conversion of longitudinal-polarized bulk THz acoustic waves to transverse polarized bulk waves and surface waves, which have applications in acoustic spectroscopy, plasmonics and optical modulation. The semiconductor acousto-optoelectronic devices to be investigated will be based on (Al)GaAs and cubic-phase (Al)GaN structures grown by molecular beam epitaxy and processed in the School of Physics and Astronomy clean room suite. Initially, we will use coherent THz acoustic waves generated using femtosecond-duration light pulses from an ultra-fast laser incident on the semiconductor surface or a thin-film metal acoustic transducer. In parallel we will further develop and optimize the saser devices so that they may in future replace the ultra-fast laser-based source. [1] ÒDynamics of a vertical cavity quantum cascade phonon laser structureÓ, Maryam, W., Akimov, A.V., Campion, R.P., Kent, A.J., Nature Communications, 4, 2184 (2013).
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2017
- Source ID
- W911NF1510191XX0
Entities
People
- Anthony Kent
Organizations
- Army Contracting Command
- United States Army
- University of Nottingham