Evidence for terahertz acoustic phonon parametric oscillator based on acousto-optic degenerate four-wave mixing in a silicon doping superlattice

Thomas E Wilson

doi:10.1103/physrevb.98.220304

Abstract

We report first evidence for a 1.0 terahertz (THz) self-starting mirrorless acoustic phonon parametric oscillator (MAPPO) produced from acousto-optic phase-conjugate degenerate four-wave (D4WM) mixing in a THz laser-pumped silicon doping superlattice (DSL). The DSL was grown by molecular beam epitaxy on a (100) boron-doped silicon substrate. A superconducting NbTiN subwavelength grating was used to couple the THz laser radiation into the DSL. Superconducting granular aluminum bolometric detection, coupled with Si:B piezophonon spectroscopy, revealed excitation of THz coherent compressional and shear waves, along the <111> direction only. The Bragg scattering condition for distributed feedback, and the energy conservation requirement for the D4WM process, were both verified. A THz MAPPO could provide a testbed for studies of non-classical acoustic phonon fields.

Highlights

We report evidence for a 1.0-THz self-starting mirrorless acoustic phonon parametric oscillator (MAPPO) produced from acousto-optic phase-conjugate degenerate four-wave (D4WM) mixing in a THz laser-pumped silicon doping superlattice (DSL)
*Corresponding author: wilsont@marshall.edu room temperature) showing gain due to the acoustoelectric effect; its gain coefficient for LA waves near 400 GHz was 8 × 103 cm−1. In this Rapid Communication, we report experimental evidence for a mirrorless acoustic phonon parametric oscillator (MAPPO) in a doping superlattice structure operating at
The MAPPO is optically pumped by nanosecond-pulsed 1.04-THz plane-polarized laser radiation

Summary

Introduction

We report evidence for a 1.0-THz self-starting mirrorless acoustic phonon parametric oscillator (MAPPO) produced from acousto-optic phase-conjugate degenerate four-wave (D4WM) mixing in a THz laser-pumped silicon doping superlattice (DSL). Current phonon studies use visiblelight pulse (VLP) transducer techniques [3] to produce and detect coherent near-THz acoustic phonons. A (femto- or picosecond) VLP produces, by electronic excitation and relaxation, a stress as a source of near-THz coherent acoustic phonons.

Results

Conclusion