Patent ID: 11892438
Assignee: ASAHI KASEI MICRODEVICES CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An optical densitometer for measuring a density of a gas or liquid of interest, the optical densitometer comprising:
a light source capable of introducing light into a core layer;
a detector capable of receiving the light that has propagated through the core layer; and
an optical waveguide, the optical waveguide comprising:
a substrate; and
the core layer comprising a light propagation portion capable of propagating the light in an extending direction of the light propagation portion, and a diffraction grating portion,

the diffraction grating portion comprising a diffraction grating region and an extension region connected to the diffraction grating region, and
a first optical coupling region included in the extension region and a second optical coupling region included in the light propagation portion being optically coupled with respect to the light propagating through the core layer, wherein
at least a portion of the diffraction grating portion is spatially separated from the light propagation portion via a material having a relatively lower refractive index than that of the core layer in a thickness direction, and
in a region where the light propagation portion and the diffraction grating portion overlap in plan view, a first distance modification region is provided in which a distance in a thickness direction between the diffraction grating portion and the light propagation portion reduces in a direction approaching from the diffraction grating region toward the first optical coupling region.