Using the small molecule TEOP (5,10,15,20-[1,4-benzodioxane-6-carboxalde]porphyrin), the in situ assembly is a very convenient and efficient approach for fabricating high-quality ordered patterns. The well-ordered patterns possess strong saturated absorptive and self-defocusing nonlinearities while the TEOP solution exhibit reverse saturated absorption. The value of the nonlinear absorption coefficient of the TEOP ordered pattern and solution differed by three orders of magnitude. [GRAPHICS]