Similarly, the absorption coefficient ( ( )) and reflectivity ( ( ) ) are closely related with 2 ( ) as described in equations . The direct relationship between optical absorption coefficient and dielectric function is illustrated in Fig. & Fig. . The threshold value of energy in ( ) to excite the peaks is known as absorption edge ( ). The absorption edge is approximately at 1.69 eV which is equivalent to electronic bandgap (1.77 eV) suggesting the direct transition of photo-excited electrons from the VBM to the CBM. However, this value increases with compressive strain and reaches 1.83 eV at 6% (blue-shift). In contrast, the absorption edge decreases with increasing tensile strain and reaches 1.30 eV at 6% of strain (red-shift). This analysis indicates that the optical threshold activity decreases to a lower value of photon energy by applying tensile strain. The equilibrium structure shows first three noticeable optical absorption peaks locating at 1.89 eV, 2.93 eV and 3.86 eV in VR region with absorbance up to 1.08×10 5 -1 . Similarly, Multiple higher absorption peaks at 6.11, 7.39, 14.26 eV with the absorbance up to 7.01×10 5 -1 (at 14.26 eV) are found in UV region. One can see that absorption peaks are more pronounced in the deep UV range as compare to VR. The exceptional long-range absorbance, from 1.69 eV to 20 eV, and multiple absorption peaks in UV and VR region indicate p-BCN as an appropriate light-harvesting material. The amplitude of these peaks slightly increases (decreases) with compressive (tensile) strain. While applying strain, these peaks slightly shift to higher energy values with reference to the equilibrium value. Further, there is no absorption of photon energy in the infrared (IR) region which indicates that the monolayer doesn't absorb heat at this range and can be operated in optical fibers and beam splitters .