After making a good understanding of electronic properties, which are inherently connected to the optical behavior of a semiconductor (Equ. 4), it is interesting to discuss the optical behavior of FBNF monolayer. The optical response is calculated by analyzing the amplitude and number of peaks in the optical response curves with the photon energy range of 0 eV to 25 eV. The incident polarized light is considered in in-plane (E‖x), and out-of-plane (E‖z) directions, which are sufficient directions to describe the optical behavior of this 2D system. The spin non-polarized calculations is performed to investigate the important optical parameters such as the real ( 1 ( )) and imaginary ( 2 ( )) parts of dielectric functions, absorption coefficient ( ( )), electron energy loss function (ELF) (L( )), refractive index ( ( )), and reflectivity ( ( )). To make a comparison, these optical parameters are plotted side by side (Fig. ) for both directions and also compared with the pristine h-BN.