Light detector

1. A light detector comprising:

a light detection substrate having at least one light receiving region and a light incident surface on which a detection target light is incident; and

a meta-lens configured by a plurality of unit structures arranged in a grid pattern and disposed on the light incident surface to focus the detection target light,

wherein when viewed in a thickness direction of the light detection substrate, an opening region in which the unit structure is not formed is provided in a region including a center of the meta-lens,

the meta-lens is formed such that a first distance is 40% or more and 90% or less of a second distance,

the second distance is a distance in the thickness direction from the meta-lens to a focus point set by the meta-lens, and

the first distance is a distance in the thickness direction from the meta-lens to a light-condensing point formed at a position closer to the light incident surface than the focus point due to the opening region being provided.

2. The light detector according to claim 1 , further comprising:

a dielectric layer disposed between the light detection substrate and the meta-lens, and having a refractive index lower than that of the light detection substrate.

3. The light detector according to claim 1 , wherein

a numerical aperture NA of the meta-lens is set so as to satisfy the following Equation (1), and

in the Equation (1), λ eff is an effective wavelength of the detection target light passing through the meta-lens, and P is a period in which the plurality of unit structures are arranged

λ

eff

4

*

P

<

N

⁢

A

<

λ

eff

2

*

P

.

(

1

)

4. The light detector according to claim 1 , wherein when viewed in the thickness direction, the opening region has a rectangular shape.

5. The light detector according to claim 1 , wherein the plurality of unit structures are configured such that a phase distribution of the meta-lens follows a quadratic phase pattern.

6. The light detector according to claim 1 , wherein the light detection substrate includes an avalanche photodiode.

7. The light detector according to claim 1 , wherein when viewed in the thickness direction, the meta-lens is formed to overlap both an adjacent region adjacent to the light receiving region and a peripheral region inside of the light receiving region along a boundary between the light receiving region and the adjacent region.

8. The light detector according to claim 1 , wherein the meta-lens is formed such that the first distance is not less than 50% and not more than 80% of the second distance.

9. The light detector according to claim 1 , wherein when viewed in the thickness direction, a width of the opening region is equal to or greater than a half of a width of the meta-lens.