Patent ID: 7437036

Claim:
A method for manufacturing an optical device, which includes an optical waveguide path and a movable portion, wherein the optical waveguide path includes a Bragg grating disposed in a middle of the optical waveguide path, wherein the movable portion is disposed near the Bragg grating and movable in accordance with a physical quantity applied to the movable portion, wherein a displacement of the movable portion provides a change of spacing of the Bragg grating so that a light passing through the optical waveguide path is changed, wherein the optical device detects the physical quantity based on a change of the light passing through the optical waveguide path, the method comprising steps of: forming the optical waveguide path with the Bragg grating on a first part of a silicon substrate; and forming the movable portion on a second part of the silicon substrate, the second part corresponding to the first part, wherein the step of forming the optical waveguide path includes steps of: forming a plurality of first structural bodies on a first side of the silicon substrate by etching the first side of the silicon substrate, wherein adjacent two first structural bodies have a first clearance therebetween, and wherein each first structural body is made of silicon; forming a plurality of second structural bodies on the first side of the silicon substrate by etching the first side of the silicon substrate, wherein adjacent two second structural bodies have a second clearance therebetween, wherein the second structural bodies intersect with the first structural bodies, and wherein each second structural body is made of silicon; embedding the first clearance with silicon oxide and converting the first structural bodies to silicon oxide first structural bodies by thermally oxidizing the silicon substrate so that the optical waveguide path is formed; and embedding the second clearance with silicon oxide and converting the second structural bodies to silicon oxide second structural bodies by thermally oxidizing the silicon substrate so that the Bragg grating is formed, and in the step of embedding the second clearance with silicon oxide, the second clearance shrinks so that a shrunk second clearance provides an air gap, and each silicon oxide second structural body with an embedded second clearance provide a glass layer.