A method for forming a micro-optical or sub-micro-optical device is provided, including: forming a photolithographic mask on a transparent support, depositing a layer of a photosensitive material of negative polarity on the face, a so called front face, of the support which supports the mask, wherein the mask is disposed under the areas where the photosensitive material should be removed, insolating the layer of the photosensitive material through the rear face of the support, developing the photosensitive material in order to obtain walls of micron or submicron cavities, removing the mask areas located at the bottom of the cavities in order to obtain cavities without any mask material between the walls, introducing a fluid into the cavities of the device, and forming a closure layer on the walls in photosensitive material.