Yuri S. Didosyan

Fast latching type optical switch

A magneto-optical latching switch with a yttrium orthoferrite optical rotator is described. The crystal remains in a given magnetic state for unlimited duration without energy supply. The response time is about 20 ns and the aperture of the optical rotator is 350 μm.

Magneto-optical rotational speed sensor

Abstract A new passive and wireless magneto-optical rotational velocity sensor is described. It is based on measuring the intensity oscillations of linearly polarized light transmitted through an orthoferrite plate and an analyzer. The plate is subjected to the action of the magnetic field of a disc whose angular velocity has to be measured. Thanks to the high velocity and smooth reproducible character of the domain wall motion in the orthoferrite plate, one can continuously measure angular velocities in a very wide range—from ultralow to the MHz range.

Magneto-optical current sensors of high bandwidth

A new current transformer is described by means of new results concerning the domain wall excitation in orthoferrites. The measured parameter is the geometrical position of the boundary between domains with opposite magnetizations. In a wide frequency band, including DC currents, the measurement results are a linear function of the measured current due to the very high domain wall velocity. They are not affected by temperature changes and mechanical factors.

Magnetooptic switch based on domain wall motion in orthoferrites

A prototype of an optical switch based on Faraday rotation in yttrium orthoferrite crystals is developed. The switch is of latching type and has an operating time below 100 ns. Integrated arrays of switches are feasible due to the dimensions of the optical rotator of less than 3 mm/sup 3/.

Latching type optical switch

An optical switch on yttrium orthoferrite crystal is developed. The switch is of latching type and has an operating time of 100 ns. Matrices of switches are feasible due to the dimensions of the optical rotator of less than 2 mm3.

Application of orthoferrites for light spot position measurements

Results of measurements of the light spot positions based on the spatial light modulation in an orthoferrite crystal are presented. The reproducibility of the measurements is 0.8 μm and the sampling rate is 600 kHz.

Magneto-optical current sensor by domain wall motion in orthoferrites

A brief review of the latest developments on optical current measurements based on the Faraday effect is presented. In all existing magneto-optical current transformers, the main measured parameter is the polarization state of the light transmitted by a sensor element. A new transformer is described by means of new results concerning the domain wall excitation. The measured parameter is the geometrical position of the boundary between domains with opposite magnetizations. In a wide frequency band, including DC currents, the measurement results are a linear function of the measured current. They are not affected by temperature changes and mechanical factors.

Magnetic field sensor by orthoferrites

Abstract Among all ferromagnets orthoferrites possess the highest velocities of domain wall motion. Dynamic properties of a magnetic field meter based on domain wall dynamics in yttrium orthoferrite are reported. It is shown that at low driving magnetic fields and at frequencies up to the MHz band domain wall dynamics can be adequately described by linear equations. In a wide range of frequencies the results of measurements do not depend on the temperature of the crystal.

Magnetization reversal and aftereffect in orthoferrites

A magnetic aftereffect of several μs duration has been discovered in 1.2 mm thick samples of yttrium orthoferrite crystals cut perpendicularly to the optical axis at 1.3 μm wavelength. The aftereffect is associated with nucleation and expansion of oppositely magnetized domains that occur in a monodomain sample after removal of an external magnetic field. Magnetization reversal processes are visualized in a Faraday setup and studied by measuring the temporal dependence of the state of polarization of a transmitted light beam.

Subsonic domain wall dynamics in yttrium orthoferrite

Abstract The domain wall (DW) velocity versus field dependence in the subsonic range of 0.2–1.1 km/s is studied. The sample is a plate of yttrium orthoferrite YFeO 3 cut perpendicular to the optical axis. The specific Faraday rotation for a wavelength of 0.63 mm equals − 2900 °/cm . A single rectilinear 180° DW was created by applying a quadrupole field. The DW motion was caused by a pulsed magnetic field and analyzed by means of dark-field measurements. Numerous results confirm the nonlinear character of the DW velocity.