Fiber Optic Tutorials

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...

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...

This is a continuation from the previous tutorial - electro-optic modulators. Optical waveguides possess many unique characteristics that do not exist in bulk optics. An important one is their ability to guide optical waves within a small cross-sectional area over a long distance. This allows for the possibility of using the transverse modulation scheme to realize very efficient modulators at very low modulation voltage. In bulk optics, the ratio of the length to the cross-sectional dimensions is limited by the diffraction effect, limiting the advantage that can be realized using transverse modulation. This limitation does not exist in waveguide optics....

This is a continuation from the previous tutorial - Pockels Effect. The index changes induced by the Pockels effect can be utilized to construct a variety of electro-optic modulators, in either bulk or waveguide structures. An electro-optically induced rotation of principal axes is not required for the functioning of an electro-optic modulator though it often accompanies the index changes. However, the directions of the principal axes in the presence of an applied electric field, whether rotated or not, have to be taken into consideration in the design and operation of an electro-optic modulator. In this tutorial, we consider the operation...