The electron energy loss function (ELF) describes the amount of energy loss through the material upon the incidence of photon energy. The multiple energy losses in the energy range 4.25 eV to 25.00 eV (Fig. ) is detected in FBNF for both directions. The major energy loss peaks arises at 9.29 eV, 10.19 eV, 13.88 eV, 15.23 eV and at 8.83 eV, 12.47 eV, 15.87 eV, 18.0 eV, 19.40 eV for FBNF in in-plane and out-of-plane direction, respectively. The energy loss is significantly lower in FBNF than the pristine counterpart in the in-plane direction. The sharpest resonance peak at 12.47 eV due to plasma frequency ( ) creates significant energy loss. The energy loss is highly anisotropic like other paramters in FBNF as well as h-BN. The absorption coefficient ( ) spectra describe the light-harvesting quality of the material. The absorption edges ( ), the threshold value of energy absorption spectra, are at 6.71 eV (red-shifted) and at 5.49 eV (blue-shifted) for in-plane and out-of-plane direction (Fig. ), respectively. Null absorption in infrared region (IR) and visible region (VR) for FBNF makes it a perfect material in optical fibers and beam splitters . The highest absorption peak is observed at 12.91 eV (≈ 9.01×10 6 -1 ) and 12.23 eV for in-plane and out-plane direction which is significantly better than pristine h-BN. The exceptional long-range absorbance, from 6.71 eV to 25 eV, and multiple absorption peaks in the ultraviolet region (UV) region make FBNF monolayer an appropriate light-harvesting material. Additionally, the strong optical anisotropy broads its applications in light polarizers and wave guides materials.