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Microwave Delay Lines with Optical Readout

IP.com Disclosure Number: IPCOM000092042D
Original Publication Date: 1968-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Smith, AW: AUTHOR

Abstract

This system realizes a delay line for microwave frequencies by use of a magnetic field. The amount of delay is read by optical devices.

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Microwave Delay Lines with Optical Readout

This system realizes a delay line for microwave frequencies by use of a magnetic field. The amount of delay is read by optical devices.

A magnetoelastic wave can be generated at a turning point in the frequency/wavelength plot of energy traversing a magnetostrictive crystal, for example, yttrium-iron-garnet YIG, by employing an RF magnetic field. One magnetoelastic wave travels into the low-field region toward the end of the crystal and another magnetoelastic travels into the high-field region in the center of the crystal. The turning point p occurs at an internal magnetic field H(i) equal to omega(m)/gamma where omega is the frequency of the magnetoelastic wave and gamma is the gyromagnetic constant. The position of this point p in the YIG crystal changes as an external field H(e) is varied, assuming that the crystal has a nonuniform demagnetization field.

When the magnetoelastic wave intercepts a laser beam, such laser light is diffracted at the Bragg angle. The frequency of the laser light is shifted by the magnetoelastic frequency omega(m), allowing the original beam of laser light to be recovered by a photodetector by heterodyning the light diffracted at the Bragg angle with part of the undiffracted laser light. The delay between the onset of the magnetoelastic wave and the output pulse of a photodetector employed to detect the heterodyned light pulses is determined by the distance between the turning point p and th...