The capability of generating photonic nanojets using dielectric cubes working in the visible light region is introduced and investigated numerically. The simulation of electric intensity distributions for a dielectric cube is performed using the finite-difference time-domain method. The focusing characteristic of the photonic nanojets is evaluated in terms of both focal length and transversal full width at half maximum along both transversal directions. Moreover, the ultra-long photonic nanojet is studied by theoretical calculations for a dielectric cube. By changing the dimension of the dielectric cube, it has been demonstrated that the focus point is moved from inside to outside the cube with a high intensity nanojet. The super resolution imaging of the dielectric cube can be expected from the focal length and the maximum intensity. The photonic nanojet enhancement and super resolution technique could be functional for the imaging of nano-scale targets on substrates and films.