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Browse Prior Art Database

Microwave Phonon Transducer, Mixer and Harmonic Generator Using a Superlattice

IP.com Disclosure Number: IPCOM000077448D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 42K

Publishing Venue

IBM

Related People

Tsu, R: AUTHOR

Abstract

The arrangements described herein make use of the phonon-electron interaction in a superlattice where the energy momentum relationship is highly nonparabolic, as a way to mix microwave phonons to generate phonon harmonics, and to produce sound waves at very high frequencies.

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Microwave Phonon Transducer, Mixer and Harmonic Generator Using a Superlattice

The arrangements described herein make use of the phonon-electron interaction in a superlattice where the energy momentum relationship is highly nonparabolic, as a way to mix microwave phonons to generate phonon harmonics, and to produce sound waves at very high frequencies.

Most superlattice structures (see U.S. Patent 3,626,257) envisioned are piezoelectric semiconductors. Due to the extreme nonparabolicity, currents induced by the deformation piezoelectric potential contain harmonics. This effect provides a means for mixing phonons. Since the velocity of sound is about 5 x 10/5/ cm/sec, for sound waves at 10/9/, 10/10/ hz, the wavelength is approximately equal to the superlattice thickness providing for enhanced coupling. This is identical to the instance of the diffusion transducer. In the instance of transducer applications, an applied field at f(o) will result in mf(o), wherein m is the order of the harmonics.

An arrangement for direct generation of high-frequency sound from a microwave source is shown in Fig. 1, where microwaves at a frequency f(o) excite a sound wave n a superlattice ,located in a cavity. The induced sound wave is transmitted out of the cavity via a transmission medium such as a quartz rod. Fig. 2 shows an arrangement wherein a sound wave at frequency f(1) may be mixed with a second sound wave at a frequency f(z) producing currents at f(1) +/- f(2), thereby providing a mixer for sound.

Referring to Fig. 3, the strain in transmission medium 2 is found to be:

(Image Omitted)

where k(1), k(2), c(1) and c(2) are the propagation constants and the elastic constants of the appropriate regions, and E(o) and E(d) are the electric fields at x = 0 and x = d.

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