Method for fabricating planar optical waveguide devices

• US 6,605,228 B1
• Filed: 07/14/2000
• Issued: 08/12/2003
• Est. Priority Date: 10/19/1998
• Status: Expired due to Fees

• Current Assignee: Omron Corporation
• Original Assignee: NHK Spring Company Limited
• Inventors: Senda, Takayuki, Natsume, Yutaka, Masuda, Michiya, Kawaguchi, Shigeru
• Primary Examiner(s): Beck, Shrive P.
• Assistant Examiner(s): OLSEN, ALLAN W
• Application Number:
  US09/616,224
• Time in Patent Office: 1,124 Days
• Field of Search: 216/24, 216/39, 653/79, 653/84, 653/85
• US Class Current: 216/24
• CPC Class Codes: G02B 2006/12038 Glass (SiO2 based materials)
• CPC Class Codes: G02B 2006/12147 Coupler
• CPC Class Codes: G02B 2006/1215 Splitter
• CPC Class Codes: G02B 2006/12176 Etching
• CPC Class Codes: G02B 6/132 by deposition of thin films

Abstract

Proposed is a method for fabricating a planar optical waveguide device having a plurality of core segments formed between a lower clad layer and an upper clad layer, in which a hot isostatic pressing process (HIP) is carried out during the fabrication process. The lower clad layer may consist of a substrate or a buffer layer formed on a substrate. Each layer may be formed either by a low-temperature film-forming process such as CVD or by the flame hydrolysis pressing process. The HIP process is also effective in eliminating voids when the core is formed in a recess of the lower clad layer. According to the tests conducted by the inventors, it was found that the HIP process can be conducted without requiring any protective layer or a gas barrier through proper selection of the condition for the HIP process, as opposed to the common belief that a protective layer or a gas barrier is essential for the HIP process.

Claims

1. A method for fabricating a planar optical waveguide device having a plurality of core segments formed between a lower clad layer and an upper clad layer, comprising the steps of:

providing a lower clad layer;

forming a recess corresponding to a desired pattern of core segments in said lower clad layer;

forming a core layer on said lower clad layer including an interior of said recess;

conducting a hot isostatic pressing process on an assembly of said lower clad layer and said core layer at a temperature higher than 800°

C. and a pressure higher than 1,000 kgf/cm²;

removing a surface layer from an assembly of said lower clad layer and said core layer until a surface of said lower clad layer is exposed, and said lower clad layer and said core layer in said recess jointly define a planar surface; and

forming an upper clad layer on said planar surface jointly defined by said lower clad layer and said core layer.

2. A method for fabricating a planar optical waveguide device according to claim 1, wherein said lower clad layer consists of a substrate.

3. A method for fabricating a planar optical waveguide device according to claim 1, wherein said lower clad layer consists of a buffer layer formed on a substrate.

4. A method for fabricating a planar optical waveguide device according to claim 1, wherein said lower clad layer, core layer and upper clad layer are all formed by a flame hydrolysis deposition process.

5. A method for fabricating a planar optical waveguide device according to claim 1, wherein said lower clad layer, core layer and upper clad layer are all formed by a film-forming process selected from the group consisting of CVD and PVD.

6. A method for fabricating a planar optical waveguide device according to claim 1, wherein at least one of said lower clad layer, core layer and upper clad layer are formed by a flame hydrolysis deposition process while the remaining layers are formed by a film-forming process selected from the group consisting of CVD and PVD.

7. A method for fabricating a planar optical waveguide device according to claim 1, wherein said hot isostatic pressing process is conducted with an outer surface of said core layer substantially exposed.