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Browse Prior Art Database

Optical Polarization Switch or Isolation

IP.com Disclosure Number: IPCOM000090117D
Original Publication Date: 1969-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Smith, AW: AUTHOR

Abstract

The optical polarization properties of light diffracted from a transverse magnetoelastic wave can be used to provide either an optical isolator or an optical switch.

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Optical Polarization Switch or Isolation

The optical polarization properties of light diffracted from a transverse magnetoelastic wave can be used to provide either an optical isolator or an optical switch.

In drawing 1, laser source 2 directs its output beam 4 onto an optical device
6. The optical output of device 6, without optical isolator 10, normally impinges on a second optical device 8 to react with elements within such device. Certain of the elements within device 8 can reflect the optical output back toward device 6, thus interfering with the proper operation of the overall optical system.

Drawing 2 shows an optical isolator for preventing reflections back Coward device 6 after an output beam is transmitted by optical device 6. Block 14 of yttrium-iron-garnet is positioned so that a magnetoelastic wave omega(m), k(m), produced by RF source 16 applied to one end of block 14, is made to traverse such block along its Z axis. A magnetic field H is originally selected to have a fixed field which causes block 14 to preferentially diffract the polarization vector E degrees of laser beam 18 that is parallel to the X axis but not diffract the E' vector that is parallel to the Z axis. Polarized beam 18 entering block 14 is diffracted by the Bragg angle theta(B) = lambdaf/2V(me) where lambda is the wavelength of the laser beam, f is the RF frequency, and V(me) is the velocity of the magnetoelastic wave through block 14. The diffracted wave beam 18' as its polarizat...