The InAs quantum dots (QDs) with dot-in-well (DWELL) structure are preferable than the conventional InAs QD heterostructures because of the carrier funneling mechanism in the DWELL structure. There are few reports on the InAs DWELL quantum dot infrared photodetectors (QDIPs). However, a complete study on the optimization of the well structure and thickness is still missing in the literature. Here, we report the optimization of InAs DWELL heterostructure for superior structural and optical properties. We have simulated the DWELL heterostructures by varying the thickness of In0.15Ga0.85As well in both sides of the InAs QD. The symmetric DWELLs with 2/2, 4/4, 6/6, 8/8, and 10/10 nm InGaAs well are considered. For the asymmetric DWELL, the underlying well is kept fixed at 2 nm, whereas the upper well thickness is varied as 4, 6, 8, and 10 nm. A decrease (increase) in the hydrostatic (biaxial) strain is observed as the well thickness is increased in both symmetric and asymmetric DWELL structures. There is a redshift in the absorption peak with thicker wells, but a cutoff in the absorption coefficient value is obtained as the well thickness is increased beyond 6 nm in both cases. The probability density functions of the carriers in the case of 6/6 nm symmetric DWELL are high, which attributes to higher oscillator strength. Thus, the 2/6 nm asymmetric DWELL is the optimum one and hence the corresponding QDIP is grown. The photoluminescence result has good match with the simulated result and the QDIP showed a mid-wave infrared (MWIR) photoresponse.