2. Guided transmissions

In the optical field, unlike the electrical field, there are several modes of propagation in the guide, depending on its dimensions (see the article Optical interconnections [E 3 652] in this treatise):

• when the cross-section of the guide is of the order of a few wavelengths, we speak of a single-mode guide;

• when the cross-section is much larger, we speak of a multimode guide.

As we have already shown, single-mode optics offer the best performance in terms of bandwidth and linear attenuation,...