Mostly, it has been seen that the imaging quality of an conventional \(2\times 2\) MMI coupler primarily dependence on two parameters. First is beat length \(L_{\pi}\) and second is \(\Delta\beta_{m}\). Since optimal MMI length \(L_{mmi}\) is proportional to the beat length \(L_{\pi}\), which is wavelength dependent Equation 3 \cite{A}, the optimal length varies with wavelength. Images will be formed at different positions along propagation direction (z) for different wavelengths. Wavelength dependence (for wide-bandwidth) of the beat length is main source of the MMI bandwidth limitation, its realized with width \(W_{mmi}\) of MMI region and also optical bandwidth is shown to inversely proportional to the number of input/output port with their position \cite{P}. Wavelength insensitive performance of MMI coupler is expected, if \(L_{\pi}\) dependent with wavelength is alleviate by prudent design. In addition to reducing \(L_{\pi}\) wavelength dependence, the parabolic relation between mode propagation constant Equation 2 needs to be fulfilled over the operational bandwidth to assure good MMI performance. From Equation 2, it is observed that wavelength dependence of \(\Delta\beta_{m}\) is inversely proportional to \(L_{\pi}(\lambda)\). Consequently, provided the beat length is designed substantially wavelength independent and access port width \(W_{g}\) is generally designed wide enough \cite{M}, so as to excite only limited number of lower order that fulfill Equation 2, the parabolic phase relation will hold and high quality imaging is expected for a broad wavelength range These considerations are the basis of our highly-broad band MMI device design.