PURPOSE: To implement a compact configuration, light weight, high stability and response and high detecting sensitivity by constituting an interferometer with an optical waveguide formed on an Si substrate, and providing a structure wherein two light paths are thermally separated by forming grooves.
CONSTITUTION: Optical waveguides 2a and 2b are formed on an Si substrate 1. Input/output optical wave guides 3a and 3b are provided for introducing input light beams, combining the input light beams at a point P and leading out the output light beams. A heater 6 and grooves 11 for thermally separating the waveguide 2a are provided at the waveguide 2a. Since the waveguide 2a is heated with the heater 6 and thermally separated with the grooves 11 in which way, temperature increased. Then the refractive index and the actual length of the light path are changed. Thus the length of the optical light path is changed. Therefore phase difference is generated between the light paths of the waveguides 2a and 2b, and interference occurs. The interference is detected with a photodetector 8. When a fluid stream is brought into contact with the substrate 1 as shown with arrows, the output obtained with the photodetector 8 is changed by the flow speed. When the species of the fluid is known, the speed is computed by said output.
KONO NAOTAKE
KITANO MASANORI
FUKUI KEITARO
PETROLEUM ENERGY CENTER FOUND