In this study, we have investigated the effect of varying In-concentration in the barrier material of Stranski-Krastanov (SK) on sub-monolayer (SML) InAs quantum dots (QDs). Four different heterostructures (A, B, C, and D) have been modeled using Nextnano software. Structures A, B, C, and D with the barrier material of GaAs, In0.15Ga0.85As, In0.25Ga0.75As, and In0.35Ga0.65As respectively have been taken into consideration. The barrier thickness has been kept constant at 7.5 nm for all the structures. The matrix material of In0.15Ga0.85As has been considered for InAs SML QDs. The biaxial and hydrostatic strain have been computed and compared. Lower magnitude of hydrostatic strain governs more carrier confinement in conduction band whereas, higher biaxial strain provides more splitting of heavy-hole and light-hole band. This results in more red-shifted photoluminescence. From the simulation results, it is observed that the biaxial strain is improved by 0.3704 % and the magnitude of hydrostatic strain is improved by 1.623 % in the InAs SK region of structure D as compared to that of structure A. Similarly, the biaxial strain is improved by 0.7677 % and the magnitude of hydrostatic strain is improved by 2.301 % in the InAs SML region of structure D as compared to that of structure A. The observed PL emission wavelength of structures A, B, C, and D were approximately 1549 nm, 1561 nm, 1572 nm, and 1584 nm respectively. Hence, the structure D provides the highest PL emission wavelength for LWIR telecommunication applications and optimal strain distribution among the other heterostructures.