Chromatic dispersion is determined by the fiber's material composition, structure and design, and by the light source's operating wavelength and spectral width. What are the detailed parameters of the optical module? Optical module center wavelength, transmission distance, loss and dispersion, laser type, fiber interface, etc. Considering that some newcomers to optical modules may not understand the letters on the optical module or the. Dispersion is the dependence of light's phase velocity or phase delay as it transmits through an optical medium on another parameter, such as optical frequency, or wavelength. Several different types of dispersion can occur inside an optic's substrate: chromatic (Figure 1), intermodal, and.