| 摘要 |
<p>A method of controlling birefringence in a rib waveguide structure manufactured in silicon is described. The rib waveguide structure comprises an elongated rib element (4) having an upper face (5) and two side faces (6). According to the method, a blanket layer of silicon nitride (8) is formed to a predetermined thickness over the rib waveguide structure directly abutting the upper face (5) and side faces (6). The thickness of the blanket layer (8) is selected to control birefringence. A silicon rib waveguide structure incorporating such a layer (8) and an evanescent coupler structure are also described.</p> |
