Design of a circular photonic crystal fiber with flattened chromatic dispersion using a defected core and selectively reduced air holes: Application to supercontinuum generation at 1.55 μm

• Circular Lattice Photonic Crystal Fiber (CL-PCF) is proposed in the aim to achieve nearly zero ultra flattened chromatic dispersion for supercontinuum generation.
• The parameters of the proposed design is optimized by using a finite-difference in frequency-domain (FDFD) method combined with the perfectly matched layer (PML) boundary condition.
• Numerical results show that an ultra flattened chromatic dispersion as small as ±0.66 ps/nm km is obtained over a broad band of 400 nm covering the E, S, C, L and U bands.
• 400 nm bandwidth infrared supercontinuum generation is demonstrated in a 25 cm length of the proposed CL-PCF by using an intense 0.1 ps width Gaussian pulse.

In this paper, we present and numerically investigate a new and simple design of Circular Lattice Photonic Crystal Fiber (CL-PCF) with near zero ultra-flattened chromatic dispersion. The near zero dispersion is obtained by introducing a defect into the solid core and the dispersion flatness is achieved by appropriately reducing the diameter of the core-neighboring air holes ring. Simulations are performed by using the finite-difference frequency-domain (FDFD) method combined with the perfectly matched layer (PML) boundary condition. Results show that an ultra-flattened chromatic dispersion as small as ±0.66 ps/nm km is obtained over a broad band of 400 nm with high nonlinearity and ultra-low confinement loss. Furthermore, the supercontinuum (SC) generation over a short length of the proposed CL-PCF is numerically investigated. Results indicate that flat SC spectrum with a Full Width at Half Maximum (FWHM) of 600 nm is achieved with 25 cm of fiber length.