US 11,892,438 B2
Optical densitometer and optical waveguide
Takaaki Furuya, Tokyo (JP); Tatsushi Yagi, Tokyo (JP); and Toshiro Sakamoto, Tokyo (JP)
Assigned to Asahi Kasei Microdevices Corporation, Tokyo (JP)
Filed by Asahi Kasei Microdevices Corporation, Tokyo (JP)
Filed on Dec. 9, 2020, as Appl. No. 17/115,792.
Claims priority of application No. 2019-224818 (JP), filed on Dec. 12, 2019; application No. 2019-224937 (JP), filed on Dec. 12, 2019; and application No. 2019-224941 (JP), filed on Dec. 12, 2019.
Prior Publication US 2021/0181103 A1, Jun. 17, 2021
Int. Cl. G01N 33/00 (2006.01); G01N 21/552 (2014.01); G02B 6/42 (2006.01); G01N 21/59 (2006.01); G02B 6/122 (2006.01); G02B 6/12 (2006.01); G02B 6/124 (2006.01)
CPC G01N 33/0027 (2013.01) [G01N 21/552 (2013.01); G01N 21/5907 (2013.01); G02B 6/122 (2013.01); G02B 6/12002 (2013.01); G02B 6/124 (2013.01); G02B 6/4215 (2013.01); G01N 2201/0635 (2013.01); G01N 2201/08 (2013.01)] 18 Claims
OG exemplary drawing
 
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.