Rare earth magneto optical materials

Rare earth magneto optical materials

In under the action of magnetic field and magnetic moment, electromagnetic properties of matter, such as permeability, permittivity, magnetization, magnetic domain structure and magnetization direction will change. Thus, the transmission characteristics of the light that leads to the material are also changed. Light to the magnetic field or magnetic moment under the action of the material, its transmission characteristics change called magneto optical effect.

Magneto optic material is a light information functional material which has the effect of magnetic light in the ultraviolet to infrared band. The use of this type of material of magnetic optical properties and optical, electrical and magnetic interactions and transformations, can be made into optical device with various functions, such as modulator, isolators, circulators, a switch, a deflector, optical information processor, a display, a memory, a laser gyro bias magnetic mirror, a magnetometer and magnetic optical sensor, printing machine and so on.

Rare earth element due to the 4f electron layer is not filled, and thus produce: not offset the magnetic moment, which is the source of strong magnetism, due to the 4f electron transition, which is the cause of the optical excitation, which leads to strong magneto optic effect. The pure rare earth metal does not show the magneto optic effect, which is due to the rare earth metal has not yet been prepared into optical materials. The strong magneto optic effect of rare earth elements can be revealed only when the rare earth elements are incorporated into optical materials such as optical glass, compound crystal, alloy film and so on.

Two, the application of rare earth magneto optic materials

Magneto optic devices are various kinds of optical information function devices, which are made of materials with magneto optic effect. Although Fala's younger brother discovered magneto optic effect in 1845, it has not been applied for more than a hundred years. Until the beginning of 60's in this century, due to the development of laser and photoelectron technology, it has made the research of magneto optic effect to the field of application. In laser application, in addition to explore a variety of new lasers and receivers outside and laser beam parameters, such as fast control of the intensity, direction and deflection, frequency, polarization state is a very important problem, magneto optical devices, is the use of magnetic optical effect constitute a variety of control device of a laser beam, development and classification of the similar to the microwave ferrite devices that due to the need for optical communication, 1966 development the magneto-optical modulator, magnetic optical switch, magnetic optical isolator, magneto optical circulator, magnetic rotator, magnetic optical phase shift is magneto optical devices. Due to the development of optical fiber technology and integrated optics, optical waveguide integrated magneto optic devices have been born since 1972. In the late 60's, due to the development of computer storage technology, magneto optical storage technology was developed. Later, due to the increasing perfection and commercialization of the holographic magnetic bubble and optical disc technology, magneto optical printing and optical disc system. The use of magnetic optical effect of cylindrical shaped domain (bubble) and the development of magnetic bubble technology. Due to the need of information technology, in the late 70's, on the basis of magnetic bubble technology, and the development of magneto optical information processor and magnetic bubble display. The development of laser gyro met "locking" problem, once frustrated, later use magneto optic effect, clever to overcome the "locking", in order to develop a full solid state (no mechanical components) magnetic light biased laser gyro. Therefore, each new type of magneto optic devices are developed on the basis of the study of magneto optic effect.

1 magneto optic modulator

A magneto optic modulator is used to modulate the beam by rotating the polarized light through a magneto optic medium. Magnetic optical modulator has wide range of application, as infrared detector of the chopper, made of infrared radiation pyrometer, high-sensitivity polarimeter, and can also be used to display the television signal transmission, distance measuring device and a variety of optical detection and transmission system.

2 magneto optic sensor

Device for detecting magnetic field or current by using magneto optic effect is called magneto optic sensor. It sets the laser, optical fiber and optical technology in one, with optical means to detect the change of magnetic field and current intensity and the state can be used for detection and monitoring of high voltage network, but also for precision measurement and remote control, telemetry, and automatic control system.

3 magnetic optical isolator

In optical fiber communication, optical information processing and measurement system needs to have a stable light source, because system of different devices connected at tend to reflect light, once the reflected light into the cavity of the laser source, the laser output is not stable, thus affecting the normal work of the whole system. A magnetic optical isolator is designed to solve this problem and the development of optical nonreciprocal devices. It can make the forward transmission of light without blocking through, and all of the fiber function device from the point of the light reflected back, so as to effectively eliminate the noise of laser source.

4 magneto optical recording

Magneto optical recording is a new and high technology developed rapidly in recent ten years. Magnetic optical recording is the most advanced information storage technology, it has both the advantages of both disk and CD-ROM. Magneto optical disk widely used in the management of state, military, public security, aviation and spaceflight, astronomy, meteorology, hydrology, geology, petroleum, mining, telecommunications, transportation, statistical planning needs of large-scale data real-time collection, recording, storing and analyzing field, in particular to set audio, image, communication, data calculation, analysis, processing and storage in one of the multimedia computer, the role of magneto optical storage system is can not be replaced by other storage.

Magneto optical storage is generated by laser heating and applied reverse magnetic field in rare earth amorphous alloy thin film magnetization perpendicular to the film plane domain, the domain information write, using the Kerr magneto optic effect is read.

Magneto optical