# Training Videos

## Magneto-optic Kerr effect

This is a continuation from the previous tutorial - Faraday effect. Reflection of a polarized optical wave from the surface of a material with an internal magnetization or from that of one subject to an external magnetic field results in a change of the polarization state and/or the reflectivity that is dependent on the magnetization or the magnetic field. This phenomenon is known as the magneto-optic Kerr effect. It is totally unrelated to, and should not be confused with, the electro-optic Kerr effect discussed in the electro-optic effect tutorial. The only connection between the two is that both were discovered...

This is a continuation from the previous tutorial - magneto-optic effects. The Faraday effect is a phenomenon based on the propagation and transmission of an optical wave through a material with the presence of a magnetic field. For the convenience of a general discussion, we consider the $$\boldsymbol{\epsilon}$$ tensor in the presence of a magnetic field or a magnetization of the form given by (7-16) [refer to the magneto-optic effects tutorial]. When there is an applied magnetic field but no spontaneous magnetization, we identify the tensor elements, $$\xi$$, $$n_\perp$$, and $$n_\parallel$$, with the corresponding elements in (7-15) [refer to the...

## Magneto-optic effects

This is a continuation from the previous tutorial - traveling-wave modulators. Magneto-optic materials have unique physical properties that offer the opportunity of constructing devices with many special functions not possible from other photonic devices. The most significant of these properties are that the linear magneto-optic effect can produce circular birefringence and that, unlike other optical effects in dielectric media, it is nonreciprocal. All practical magneto-optic devices exploit one or both of these two properties. Important applications of these devices include polarization control, optical isolation, optical modulation, and magneto-optic recording. The basic principles of magneto-optic effects, as well as the functions of various...

This is a continuation from the previous tutorial - guided-wave electro-optic modulators. At a low modulation frequency, the time it takes for the optical wave to travel through an electro-optic modulator is short compared to the modulation period. This situation is characterized by the condition that $$f\tau_\text{tr}\lt1$$, where $$f$$ is the modulation frequency and $$\tau_\text{tr}$$ is the transit time for the optical wave to propagate through the modulator. In this case, the modulator can be considered as a lumped device because its length is small compared to the wavelength of the modulation field. The 3-dB modulation bandwidth, $$f_\text{3dB}$$, of a...