Product of and process for forming tapered waveguides

Abstract

A method of forming a tapered optical waveguide within a substrate (2). An appropriate substrate (2) is coated with a layer of barrier material (4) such as silicon dioxide which provides a relatively tight matrix relative to the open matrix of the substrate (2). The barrier material (4) is deposited on the substrate with a sloping variable thickness that is inversely related to the desired depth of the waveguide taper. The barrier material (4) can be deposited through a vacuum deposition technique and subsequently subjected to ion-milling to provide the desired taper. An appropriate source of metal ions (6), such as silver, capable of being transferred, such as by diffusion into the substrate (2) for increasing the refractive index and thereby defining a waveguide, is then transmitted to and through the barrier material (4). The metal (6) may be coated on the tapered barrier material (4), and then diffused into the substrate (2) through the barrier material (4) which provides a controlled transmission of the ions proportional to its thickness. The substrate ( 2) can then be cleaned to strip both the barrier material (4) and residual metal (6) for subsequent processing. The resulting product of this process is a superior tapered optical waveguide device that can be economically manufactured.