In a single-mode optical fiber, the zero-dispersion wavelength is the wavelength or wavelengths at which material dispersion and waveguide dispersion cancel one another. In all silica-based optical fibers, minimum material dispersion occurs naturally at a wavelength of approximately 1300nm. Single-mode fibers may be made of silica-based glasses containing dopants that shift the material-dispersion wavelength, and thus, the zero-dispersion wavelength, toward the minimum-loss window at approximately 1550nm. The engineering tradeoff is a slight increase in the minimum attenuation coefficient. Such fiber is called dispersion-shifted fiber.
Another way to alter the dispersion is changing the core size and the refractive indices of the material of core and cladding. Because fiber optic materials are already highly optimized for low scattering and high transparency alternative ways to change the refractive index were investigated. As a straight forward solution tapered fibers and holey fibers or photonic crystal fibers (PCF) were produced. Essentially they replace the cladding by air. This improves the contrast of refractive indices by a factor of 10. Therefore the effective index is changed, especially for longer wavelengths. This type of refractive index change versus wavelength due to different geometry is called waveguide dispersion. As these narrow waveguides (~1-3 µm core diameter) are combined with ultrashort pulses at the zero-dispersion wavelength pulses are not instantly destroyed by dispersion. After reaching a certain peak power within the pulse the non-linear refractive index starts to play an important role leading to frequency generation processes like self-phase modulation (SPM), modulational instability, soliton generation and soliton fission, cross phase modulation (XPM) and others. All these processes generate new frequency components, meaning that narrow bandwidth light literally explodes in a wide range of new colours, called supercontinuum generation.
The term is also used, more loosely, in multi-mode optical fiber. There, it refers to the wavelength at which the material dispersion is minimum, i.e. essentially zero. This is more accurately called the minimum-dispersion wavelength.
The rate of change of dispersion with respect to wavelength at the zero-dispersion point is called the zero-dispersion slope. Doubly and quadruply clad single-mode fibers have two zero-dispersion points, and thus two zero-dispersion
- Nonzero dispersion shifted fiber
Wikimedia Foundation. 2010.
Look at other dictionaries:
Dispersion-shifted fiber — (DSF) is a type of optical fiber made to optimize both low dispersion and low attenuation. Dispersion Shifted Fiber is a type of single mode optical fiber with a core clad index profile tailored to shift the zero dispersion wavelength from the… … Wikipedia
Dispersion (optics) — This article is about dispersion of waves in optics. For other forms of dispersion, see Dispersion (disambiguation). In a prism, material dispersion (a wavelength dependent refractive index) causes different colors to refract at different angles … Wikipedia
Dispersion (water waves) — This article is about dispersion of waves on a water surface. For other forms of dispersion, see Dispersion (disambiguation). In fluid dynamics, dispersion of water waves generally refers to frequency dispersion, which means that waves of… … Wikipedia
dispersion — 1. The act of dispersing or of being dispersed. SYN: dispersal. 2. Incorporation of the particles of one substance into the mass of another, including solutions, suspensions, and colloidal dispersions (solutions). 3. Specifically, what is usually … Medical dictionary
Nonzero dispersion-shifted fiber — (NZDSF), specified in ITU T G.655, is a type of single mode optical fiber which was designed to overcome the problems of dispersion shifted fiber. NZDSF is available in two primary flavors: NZD+ and NZD , which differ in their zero dispersion… … Wikipedia
Material dispersion coefficient — In an optical fiber, the material dispersion coefficient, M(λ), characterizes the amount of pulse broadening by material dispersion per unit length of fiber and per unit of spectral width. It is usually expressed in picoseconds per… … Wikipedia
telecommunications media — Introduction equipment and systems metal wire, terrestrial and satellite radio, and optical fibre employed in the transmission of electromagnetic signals. Transmission media and the problem of signal degradation Every… … Universalium
List of wave topics — This is a list of wave topics.0 ndash;9*21 cm lineA*Abbe prism *absorption spectrum *acoustics *Airy disc *Airy wave theory *Alfvén wave *Alpha waves *amphidromic point *amplitude *amplitude modulation *analog sound vs. digital sound *animal… … Wikipedia
List of electronics topics — Alphabetization has been neglected in some parts of this article (the b section in particular). You can help by editing it. This is a list of communications, computers, electronic circuits, fiberoptics, microelectronics, medical electronics,… … Wikipedia
Fiber-optic communication — An optical fiber junction box. The yellow cables are single mode fibers; the orange and blue cables are multi mode fibers: 50/125 µm OM2 and 50/125 µm OM3 fibers respectively. Fiber optic communication is a method of transmitting information from … Wikipedia