Light detector

Patent metadata

Field	Value
Publication number	US-12270701-B2
Application number	US-202418610669-A
Country	US
Kind code	B2
Filing date	Mar 20, 2024
Priority date	May 9, 2022
Publication date	Apr 8, 2025
Grant date	Apr 8, 2025

Abstract

The light detector includes 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 including a plurality of unit structures arranged in a grid pattern and disposed on the light incident surface to focus the detection target light. When viewed in a thickness direction of the light detection substrate, an opening region in which no unit structure is formed is provided in a region including a center of the meta-lens.

First claim

What is claimed is:

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 plurality of unit structures are configured such that a phase distribution of the meta-lens follows a quadratic phase pattern,
a width of each unit structure constituting the meta-lens is set such that phase Φ (x, y) at each coordinate (x, y) satisfies the following Equation (1), and
in the Equation (1), the coordinate (x, y) is two dimensional coordinate in a case where the center of the meta-lens is set as an origin (0, 0) when viewed in the thickness direction, λ eff is an effective wavelength of the detection target light passing through the meta-lens, and f is a focal length in accordance with a maximum angle between the detection target light passing through the meta-lens and an optical axis of the meta-lens

φ
⁡
(

x
,
y

)

=

-

2
⁢
π

λ
eff

⁢

2
⁢
f

(

x
2

+

y
2

)

2

.

(
1
)

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 (2), and in the Equation (2), λ eff is the 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

.

(
2
)

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 light detection substrate includes an avalanche photodiode.

6. 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.

7. The light detector according to claim 1 , wherein
the meta-lens is formed such that a first distance is shorter than a second distance, and
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.

8. The light detector according to claim 7 , wherein the meta-lens is formed such that the first distance is 40% or more and 90% or less of the second distance.

9. The light detector according to claim 8 , 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.

10. 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.

Assignees

• Hamamatsu Photonics Kk

Inventors

• UENOYAMA Soh
• Hashimoto Takuya

Classifications

• G01J1/0411 Primary

  using focussing or collimating elements, i.e. lenses or mirrors; Aberration correction · CPC title

• G01J2001/4466

  Avalanche · CPC title

• H10F30/225

  the potential barrier working in avalanche mode, e.g. avalanche photodiodes · CPC title

• H10F77/413

  directly associated or integrated with the devices, e.g. back reflectors (directly associated or integrated with photovoltaic cells H10F77/42) · CPC title

• H10F39/8063 Primary

  Microlenses · CPC title