We present composition development of borosilicate glasses for fabrication of high refractive index contrast, all-solid photonic crystal fibers. An oxide system composed of SiO2B2O3Al2O3Li2ONa2OK2O was adjusted to match thermal properties of selected highly nonlinear, lead bismuth gallium silicate glass. A high difference of refractive index of 0.376 is achieved at a wavelength of 1550 nm. We proved experimentally that the developed pair of glasses enables to draw optical fibers, and we propose a design of a photonic crystal fiber structure for broadband supercontinuum generation.