Numerical simulation of a fiber optic parametric oscillator to produce picosecond narrowband pulses for coherent anti-Stokes Raman spectroscopy has been performed by an open source Python-based library using an extremely wide range of parameters, such as the pump pulse duration, parametric frequency shift, spectral bandwidth of the pump, and the parametric pulses. It required an extremely large calculation window, both in time and spectral domains. We managed to speed up the simulation 50 times using a graphic processor unit that allowed us to define the areas of stability for different lengths of standard passive (5-100 m) and photonic crystal (23-100 cm) fibers used in the external linear oscillator cavity. It was shown that highly chirped dissipative solitons at a wavelength about 800 nm can be generated with energy up to 55 nJ, which is limited by the pump depletion and self-phase modulation effects.