Abstract: A methodical approach is introduced to establish energy dispersion relation with hole sub-band states and optical gain spectra for variant growth directions such as [00 1], [1 1 0], [1 1 1], [1 1 3] and [1 1 1] of compressively strained InGaAs/GaAs quantum well (QW) architecture by solving envelope function equation using finite difference method. It is demonstrated that there is a substantial correlation between optical gain and its emission wavelength amidst a particular crystal orientation of the QW. From the MATLAB simulation results, it can be settled that the dispersion relation between hole sub-band states, optical gain, and the threshold current density in [1 1 1] direction deviates exclusively from the other directions, in particular, the more conventional [0 0 1]. The regular optical gains are inspected 2750 cm-1,3250 cm-1, 2800 cm-1, 2900 cm-1,and 1900 cm-1 in [0 0 1], [1 1 0], [1 1 1], [1 1 3], and [1 3 1] crystal orientations, respectively, when the injection carrier density is 2 × 1018 cm-3. Eventually, the highest optical power and the lowest threshold current are attained in orientation [1 1 0] while the number of quantum well is five.