  We have performed a numerical analysis of the structural dependence of the
PCF parameters towards ultra-flat dispersion in the C-band of communication
wavelength. The technique is based on regular square-lattice PCF with all the
air-hole of same uniform diameter and the effective size of the air-holes are
modified with a selective infiltration of the air-holes with liquids. The
dependence of the PCF structural parameters namely air-hole diameter and
hole-to-hole distance along with the infiltrating liquid has been investigated
in details. It is shown that the infiltrating liquid has critical influence on
both the slope and value of dispersion, while pitch only changes the dispersion
value whereas air-hole diameter modifies the slope of the dispersion. Our
numerical investigation establishes dispersion values as small as
0+-0.58ps/(nm-km) over a bandwidth of 622nm in the communication wavelength
band (C-band). The proposed design study will be very helpful in high power
applications like broadband smooth supercontinuum generation, ASE suppressed
amplification etc.
