It is of technical interest in the fields of communications, broadcasting and television, due to its physical properties of low transmission loss, large bandwidth and light weight.
In other words, it is necessary to solve the add/drop multiplexing problem of the upper/lower path in the optical fiber transmission system, and at the same time, the cost of the add/drop wavelength must be minimized.
Waveguide dispersion is usually the tendency effective refractive index of a mode that tends to vary with wavelength.
In the submarine optical cable transmission system, two kinds of optical fibers with positive and negative dispersion are combined to form a transmission system for dispersion management.
With the increase in the distance and capacity of the transmission system, a large number of wavelength division multiplexing (WDM) and dense wavelength division multiplexing (DWDM) systems have been put into use.
In these systems, in order to perform dispersion compensation, a double-clad and triple-clad DCF with refractive index distribution that can work in the C-band and L-band has been developed.
[12] In recent years, due to the increase in the number of wavelength division multiplexing in the DWDM transmission system and the development of high speed, the polarization maintaining fiber has been more widely used.