We present a numerical investigation of the generation of an ultra-broadband optical similariton spectrum in a photonic crystal fiber (PCF) with a carbon disulfide core through Raman amplification. The proposed PCF has an extremely high nonlinear coefficient of 4519 W−1km−1 at a telecommunication wavelength of 1550 nm and exhibits near-zero ultraflattened normal dispersion of −1.5(ps/nm/km) as well as low confinement loss of about 10−9 dB/m at 1550 nm. The numerical study was conducted using full vectorial finite-element method with a circular perfectly matched layer as a boundary condition. The similariton generated in the proposed PCF has an ultra-broadband and flat spectrum centered at 1550 nm, which spans from 1383 to 1719 nm via 14 mW input peak power and over a fiber length of only 83 cm. This continuum spectrum covers both C and L bands and can be divided into several narrow bands centered at the wavelengths of the wavelength division multiplexing channels.