Patent ID: 7329481
Filing Date: 2008-02-12
Classification: G02B,H01L

Abstract:
1. A method of forming a substrate optical waveguide having a propagation axis along which light is conveyed, a cladding layer, and a core element, the core element having an elongated dimension collinear with the waveguide's propagation axis and a transverse cross-section transverse to the elongated dimension, the method comprising the steps of: (a) forming a lower cladding layer of positive-type photosensitive cladding material; (b) exposing the cladding layer to actinic radiation through a first gray-scale mask; (c) developing the exposed pattern to form a groove located in the lower cladding layer and having three-dimensional features, the remaining portion of the lower cladding layer still being sensitive to actinic radiation; (d) thereafter treating the developed lower cladding layer to reduce its sensitivity to actinic radiation; (e) thereafter forming a core layer of photosensitive core material over the groove and the treated lower cladding layer; (f) exposing the core layer to actinic radiation through a second gray-scale mask; and (g) developing the exposed pattern to form an element of core material located over the groove and having three-dimensional features.