In this article, we report the significant improvement with the tunable character of optical absorption characteristics of MQW (multi quantum well) GaAs/AlGaAs nano-scale heterostructure. The improvement and tunability of the optical characteristics have been studied via optimization of composition of the barrier layer, quantum well width and external uniaxial pressure application on the structure. A six band Kohn-Luttinger (K-L) Hamiltonian has been solved to determine the electrons and hole's wave functions, their localizations in the structure along with their discrete (dispersed) energies and finally the optical absorption characteristics. Under uniaxial (001) pressure in the range of 5 GPa to 25 GPa, a remarkable improvement in the optical absorption (6000 cm(-1) to 9000 cm(-1)) along with red shift of wavelength has been reported in this paper. Thus, the proposed heterostructure with the optimized Al content can suitably be utilized in the designing of photo-detector and optical sensor operating in the visible-NIR (near infrared) wavelength region.