Optical concentration measuring device

An optical concentration measuring device for measuring a concentration of a target component in a gas, the optical concentration measuring device comprising:

• an acoustic cavity that has a gas inlet opening and contains the gas introduced therein via the gas inlet opening;
• an optical part installed within the acoustic cavity;
• and
• an acoustic transducer installed within the acoustic cavity,
• wherein the optical part includes one or more of each of a light source that emits light including a wavelength that is absorbed by the target component and an optical waveguide which is optically connected to the light source and inside which the light from the light source propagates and at least a portion of which is exposed to a space within the acoustic cavity, and
• the acoustic transducer outputs an electrical signal according to a pressure fluctuation within the acoustic cavity that is generated by causing the target component included in the gas that is present around the optical waveguide and having a lower refractive index than the optical waveguide to absorb an evanescent wave that leaks to an outside of the optical waveguide during propagation of the light from the light source within the optical waveguide.