Hybrid photonic crystal fiber with elliptical micro air hole as an efficient supercontinuum source

A unique design of a pure silica hybrid photonic crystal fiber consisting of three circular rings and one octagonal ring lattices of air holes bounding silica core has been simulated for the generation of wide super continuum spectrum extending from ultraviolet to near infrared. Further modifications of the fiber core with elliptical air hole, manipulated the dispersion profile of the fundamental mode and it generated two zero dispersion wavelengths. The insertion of air hole enhanced the value of nonlinear coefficient, typically from 75 W(-1)km(-1) to 466 W(-1)km(-1) (at 1550 nm) for an optimum PCF with ellipticity 0.93, keeping the single mode guidance. Numerical aperture of the fibers was found to increase substantially from 0.56 to 0.86 correspondingly to the ellipticity 0.72 to 0.93 at 1550 nm. Pumping with femtosecond pulses in the anomalous dispersion regime made the spectrum broad. At 1000 W pump, a bandwidth of approximate to 1472 nm (491 to 1963 nm) was obtained for a fiber of 1 m length with pulse duration of 200 fs. The characteristics of the proposed fiber indicate that it can find numerous applications in a variety of fields, especially in ophthalmology, dentistry and imaging using optical coherence tomography.