NLS-Glossary

is due to the dispersion of a traveling pulse of light along an optical fiber as a result of the wavelength dependence of the propagation characteristics and waveguide properties but excluding multimode dispersion. Chromatic dispersion arises as a result of the range of wavelengths in the emission spectrum of the emitter (e.g. LED or laser diode) that are coupled into the fiber. It is the combination of material dispersion and waveguide dispersion.

$D_{ch}$ is time spread of a propagating optical pulse in an optical guide per unit length and per unit spectral wavelength width due to the wavelength dependence of all the guide properties. If $\delta \lambda$ is the spread of the excitation wavelengths coupled into the fiber, $\delta \tau$ is the spread in propagation times of these different wavelengths, L is the fiber length then, $D_{ch}=\frac{1}{L}\frac{\delta \tau }{\lambda \delta }$ The overall chromatic dispersion coefficient can be written as $D_{ch}=D_m+D_w+D_p$ where Dm, Dw and Dp are the material, waveguide and profile dispersion coefficients.

is a medium in which the right and left handed circularly polarized waves propagate with different velocities and experience different refractive indices; $n_{R }$and $n_L$. Since optically active materials naturally rotate the optical field, it is not unreasonable to expect that a circularly polarized light with its optical field rotating in the same sense as the optical activity will find it easier to travel through the medium. Thus, an optically active medium possesses different refractive indices for right and left handed circularly polarized light and exhibits circularly birefringence. 

has the magnitude of the field vector E constant but its tip at a given location on direction of propagation, e.g. z -direction, traces out a circle by rotating either in a clockwise sense, right circularly polarized, with time, as observed by the receiver of the wave, or in a counterclockwise sense, left circularly polarized.

is the dielectric layer that surrounds the dielectric core of an optical waveguide.                                                                                                                                                           

The revised classification system Class (Class 1)
Laser is safe under all conditions of normal use. This means the maximum permissible exposure (MPE) cannot be exceeded. This class includes high-power lasers within an enclosure that prevents exposure to the radiation and that cannot be opened without shutting down the laser. For example, a continuous laser at 600 nm can emit up to 0.39 mW, but for shorter wavelengths, the maximum emission is lower because of the potential of those wavelengths to generate photochemical damage. The maximum emission is also
related to the pulse duration in the case of pulsed lasers and the degree of spatial coherence.