Abstract
Holographic thin film couplers are used in integrated optics to couple a laser beam into and out of optical wave guides. A few millimetres wide photo resist grating is superimposed on top of a dielectric slab and its struck by a limited beam with width L. For certain values theta(R) of the macroscopic incidence theta(O) an important fraction of the incident energy is coupled into the leaky wave guides formed by the thin dielectric slab and its modulated coating.
In this paper we develop an easy method to determine the coupling angle theta(R) and transmission ratio TR. We optimised the width of the laser beam versus the physical and geometrical parameters of the coupler.