Dye films for optical demonstrations in the undergraduate laboratory

Abstract

Homogenous films are needed in optical applications of dye doped polymers; for example in holography, in holographical memories or in phase conjugation. Typically organic and bio-organic films are made in the laboratories by pouring the dye-polymer solution onto the substrate, which leads often to inhomogenities in the thickness and thus in the optical density, especially by inexperienced students. We have made good quality dye films with optical densities varying by ±10% by using commercial gelatin plates and soaking them in the dye solution. We present the influence of the processing parameters to the optical density of the methylene blue and erythrosin gelatin films. The phase conjugation intensity in degenerate four wave mixing experiment is shown as an example of the optical experiments realized in the undergraduate laboratory.