Optical device, photodetection system, and method for manufacturing the same
An optical device includes a first substrate having a first surface, a second substrate having a second surface, at least one optical waveguide, and a plurality of spacers, disposed on at least either the first surface or the second surface, that include a first portion and a second portion. The first portion of the plurality of elastic spacers is at least one elastic spacer located in a region between the first substrate and the second substrate in which the first substrate and the second substrate overlap each other as seen from an angle parallel with a direction perpendicular to the first surface. The second portion of the plurality of elastic spacers is at least one elastic spacer located in a region in which the first substrate and the second substrate do not overlap each other as seen from an angle parallel with the direction perpendicular to the first surface.
1. An optical device comprising:
a first substrate having a first surface spreading along a first direction and a second direction intersecting the first direction;
a second substrate having a second surface that at least partially faces the first surface and that has a different area from an area of the first surface;
at least one optical waveguide extending along the first direction between the first substrate and the second substrate; and
a plurality of elastic spacers, disposed on at least either the first surface or the second surface, that include a first portion and a second portion, wherein:
the first portion of the plurality of elastic spacers is at least one elastic spacer located in a region between the first substrate and the second substrate in which the first substrate and the second substrate overlap each other as seen from an angle parallel with a direction perpendicular to the first surface,
the second portion of the plurality of elastic spacers is at least one elastic spacer located in a region in which the first substrate and the second substrate do not overlap each other as seen from an angle parallel with the direction perpendicular to the first surface,
each of the at least one optical waveguide includes a first portion disposed in a region between the first substrate and the second substrate in which the first substrate and the second substrate overlap each other and a second portion disposed in a region in which the first substrate and the second substrate do not overlap each other,
the at least one optical waveguide comprises a plurality of optical waveguides, and
at least a part of the second portion of the plurality of elastic spacers is located around the second portion of each of the plurality of optical waveguides.
2. The optical device according to claim 1 , further comprising a plurality of partition walls, arranged in the second direction between the first substrate and the second substrate, each of which extends along the first direction,
wherein a modulus of elasticity of each of the plurality of elastic spacers is smaller than a modulus of elasticity of each of the plurality of partition walls.
3. The optical device according to claim 2 , wherein
the plurality of partition walls are directly or indirectly sandwiched between the first substrate and the second substrate, and
a ratio with which each of the plurality of elastic spacer deforms in the direction perpendicular to the first surface by being sandwiched between the first substrate and the second substrate is higher than a ratio with which each of the plurality of partition walls deforms in the perpendicular direction by being sandwiched between the first substrate and the second substrate.
4. The optical device according to claim 1 , wherein each of the plurality of elastic spacers has a columnar shape.
5. The optical device according to claim 1 , wherein each of the at least one optical waveguide includes a third portion located between two adjacent partition walls and includes a first grating in the third portion.
6. The optical device according to claim 5 , wherein each of the at least one optical waveguide includes a second grating in the second portion of the plurality of elastic spacers.
7. The optical device according to claim 1 , further comprising a seal member that fixes a gap between the first substrate and the second substrate, wherein
the at least one optical waveguide has a structure in which one or more first optical waveguides and one or more second optical waveguides are connected to each other, respectively, and
the seal member surrounds the one or more first optical waveguides when seen from an angle parallel with the direction perpendicular to the first surface.
8. The optical device according to claim 7 , wherein
the one or more first optical waveguides each include one or more dielectric members extending along the first direction, and
a region surrounded by the seal member between the first substrate and the second substrate is filled with a member that is identical to the one or more dielectric members.
9. The optical device according to claim 8 , wherein
the one or more first optical waveguides include a structure that is capable of adjusting refractive indices of the one or more dielectric members, and
a direction of light that is emitted via the first substrate or the second substrate from the one or more first optical waveguides or a direction of incidence of light that is taken into the one or more first optical waveguides via the first substrate or the second substrate is changed by adjusting the refractive indices of the one or more dielectric members.
10. The optical device according to claim 9 , further comprising a pair of electrodes between which the one or more dielectric members are sandwiched,
wherein
the one or more dielectric members contain a liquid crystal material or an electro-optical material, and
the refractive indices of the one or more dielectric members are adjusted by applying a voltage to the pair of electrodes.
11. The optical device according to claim 10 , further comprising one or more phase shifters connected either directly or via other waveguides to the one or more first optical waveguides, respectively,
wherein the direction of the light that is emitted via the first substrate or the second substrate from the one or more first optical waveguides or the direction of incidence of the light that is taken into the one or more first optical waveguides via the first substrate or the second substrate is changed by varying differences in phase among lights passing through the one or more phase shifters.
12. The optical device according claim 1 , wherein the one or more first optical waveguides each include one or more dielectric members extending along the first direction,
the optical device further comprising two mirrors located between the first substrate and the one or more dielectric members and between the second substrate and the one or more dielectric members, respectively.
13. The optical device according to claim 12 , wherein at least a part of the first portion of the plurality of elastic spacers is located outside a region sandwiched between the two mirrors.
14. A photodetection system comprising:
the optical device according to claim 1 ;
a photodetector that detects light emitted from the optical device and reflected from a physical object; and
a signal processing circuit that generates distance distribution data based on an output from the photodetector.