Modeling dispersion in optical fibers: applications to dispersion tailoring and dispersion compensation

Abstract

The phenomenon of temporal pulse dispersion, which is a key characteristic of an optical fiber communication system is described from the first principles. Beginning with the basics of dispersion in a bulk medium, these concepts are then applied to propagation of a pulse in an optical fiber. Details of modeling dispersion are then described in the context of dispersion tailoring and dispersion compensation with a view to form the foundation for subsequent chapters on dispersion compensation that follow in this report. Basic physics behind the design target for dispersion compensating fibers is discussed, which should be useful to fiber designers.

Dispersion compensation using high-positive dispersive optical fibers

“…On the other hand, increasing the number of accommodated sub-channels results in reduced space between adjacent sub-channels, more transmitted optical power, and more sensitivity to destructive fiber nonlinear effects. Consequently, both increasing the per-channel bit rate and the number of accommodated sub-channels lead to excessive sensitivity to certain fiber impairments that degrade the clean transmission of the optical signal [5] . Practically, the increased optical power along with tighter sub-channel spacing and longer transmission distances translate to a trade-off between nonlinear propagation effects and chromatic dispersion in a fiber optic communication system [6] .…”

“…Compensation can be achieved in the optical domain by the use of different dispersion compensation devices, such as dispersion compensating gratings, dispersion compensating fibers (DCFs), dispersion compensating arrayed waveguides, etc. [5,9,10] . Electronic dispersion compensators are also proposed to compensate for the accumulated dispersion in the electrical domain [11,12] .…”

“…Since the dispersion coefficient of the transmission optical fiber is usually positive, the conventional DCF should exhibit a negative dispersion coefficient. They should also have dispersion slope matching, low bend loss, low propagation loss, and a relatively large mode effective area [5,13] . Design trade-offs to meet some of these requirements are necessary, e.g., a small dispersion coefficient is usually characterized by a small mode effective area and, consequently, large nonlinear effects and vice versa [5,6,9,13] .…”

“…They should also have dispersion slope matching, low bend loss, low propagation loss, and a relatively large mode effective area [5,13] . Design trade-offs to meet some of these requirements are necessary, e.g., a small dispersion coefficient is usually characterized by a small mode effective area and, consequently, large nonlinear effects and vice versa [5,6,9,13] . In this Letter, we take the opposite direction and show how an optical fiber with a high-positive dispersion coefficient can also be used to compensate for the dispersion.…”

Application Specific Optical Fibers

“…2). For quantitative purposes, dispersion is expressed through dispersion coefficient (D) defined as [Thyagarajan & Pal, 2007] 2 0 2 00…”