Graded-index structure for optical systems

Patent metadata

Field	Value
Publication number	US-10084101-B2
Application number	US-201615345015-A
Country	US
Kind code	B2
Filing date	Nov 7, 2016
Priority date	Nov 7, 2016
Publication date	Sep 25, 2018
Grant date	Sep 25, 2018

Abstract

An optical system and photo sensor pixel are provided. The photo sensor pixel includes a substrate including an active region and a peripheral region that is peripheral to the active region, an optical sensor disposed at the active region of the substrate and configured to receive light and output a measurement signal based on the received light, and an encapsulation layer disposed over the active region and the first peripheral region of the substrate. The encapsulation layer includes at least one subwavelength-based graded index structure provided over the peripheral region of the substrate, and the subwavelength-based graded index structure is configured to redirect the light from a region over the peripheral region onto the optical sensor.

First claim

What is claimed is:

1. A photo sensor pixel comprising:
a substrate including an active region and a peripheral region that is peripheral to the active region;
an optical sensor disposed at the active region of the substrate and configured to receive light and output a measurement signal based on the received light; and
an encapsulation layer disposed over the active region and the peripheral region of the substrate, wherein the encapsulation layer includes a subwavelength-based graded index structure provided over the peripheral region of the substrate,
wherein the subwavelength-based graded index structure is configured to redirect the light from a region over the peripheral region onto the optical sensor, and
wherein the subwavelength-based graded index structure is excluded from a region over the active region.

2. The photo sensor pixel of claim 1 , further comprising:
a peripheral circuit disposed on the substrate in the peripheral region such that the peripheral circuit is between the substrate and the subwavelength-based graded index structure.

3. The photo sensor pixel of claim 1 , wherein:
the subwavelength-based graded index structure comprises a plurality of grating structures made of a first material having a first refractive index and a plurality of trenches filled with a second material having a second refractive index, wherein the first refractive index is higher than the second refractive index.

4. The photo sensor pixel of claim 3 , wherein:
the plurality of grating structures alternate on a one-by-one basis with the plurality of trenches,
the plurality of grating structures are integral with the encapsulation layer, and
the plurality of trenches are etched into the encapsulation layer.

5. The photo sensor pixel of claim 3 , further comprising:
a plurality of plugs, where each of the plurality of plugs seals an opening of a corresponding trench of the plurality of the trenches.

6. The photo sensor pixel of claim 3 , further comprising:
a plug layer configured to seal openings of the plurality of the trenches.

7. The photo sensor pixel of claim 3 , wherein:
the first material is one selected from silicon and silicon oxide, and
the second material is one selected from air, a vacuum and oxide.

8. The photo sensor pixel of claim 3 , wherein:
the subwavelength-based graded index structure comprises a graded index pattern formed by an alternating arrangement of the plurality of grating structures and the plurality of trenches.

9. The photo sensor pixel of claim 8 , wherein the graded index pattern has a varied duty ratio that controls a local effective refractive index of the subwavelength-based graded index structure.

10. The photo sensor pixel of claim 9 , wherein the local effective refractive index varies along a horizontal direction.

11. The photo sensor pixel of claim 9 , wherein:
a first local effective index at an inner region of the subwavelength-based graded index structure is different from a second local effective index at an outer region of the subwavelength-based graded index structure such that the light impinging the subwavelength-based graded index structure at the inner and the outer regions are redirected towards the optical sensor.

12. The photo sensor pixel of claim 8 , wherein the graded index pattern has a period smaller than a ratio of a wavelength of the light and the first refractive index.

13. The photo sensor pixel of claim 3 , wherein the subwavelength-based graded index structure is configured with effective refraction indices for transverse electric (TE) polarization and transverse magnetic (TM) polarization that differ by at most 10%.

14. The photo sensor pixel of claim 3 , wherein the plurality of trenches, disposed over the peripheral region, encircle the active region.

15. An optical system comprising:
a substrate including an active region and a peripheral region that is peripheral to the active region;
an optical sensor disposed at the active region of the substrate and configured to receive light and output a measurement signal based on the received light; and
an encapsulation layer disposed over the active region and the peripheral region of the substrate, wherein the encapsulation layer includes at least one subwavelength-based graded index structure provided over the peripheral region of the substrate,
wherein the subwavelength-based graded index structure is configured to redirect the light from a region over the peripheral region onto the optical sensor,
wherein the subwavelength-based graded index structure comprises a graded index pattern, formed by a one-by-one alternating arrangement of grating structures and trenches, and that has a local effective refractive index that varies over the peripheral region, and
wherein the active region is disposed between a first side of the peripheral region and a second side of the peripheral region, and wherein the local effective refractive index of the subwavelength-based graded index structure increases from an outer region of the first side of the peripheral region towards an inner region of the first side of the peripheral region, and the local effective refractive index increases from an outer region of the second side of the peripheral region towards an inner region of the second side of the peripheral region.

16. A optical system comprising:
a substrate including an active region and a peripheral region that is peripheral to the active region;
an optical sensor disposed at the active region of the substrate and configured to receive light and output a measurement signal based on the received light; and
at least one subwavelength-based graded index structure provided over the peripheral region of the substrate, wherein the subwavelength-based graded index structure is configured to redirect the light from a region over the peripheral region onto the optical sensor,
wherein the at least one subwavelength-based graded index structure is excluded from a region over the active region.

17. The optical system of claim 15 , wherein the subwavelength-based graded index structure is excluded from a region over the active region.

18. The photo sensor pixel of claim 1 , wherein the subwavelength-based graded index structure comprises a graded index pattern having a varied duty ratio such that a local effective refractive index of the subwavelength-based graded index structure varies according to the varied duty ratio, wherein light impinging at an inner region of the subwavelength-based graded index structure is redirected at a first angle towards the optical sensor and light impinging at an outer region of the subwavelength-based graded index structure is redirected at a second angle, different from the first angle, towards the optical sensor such that the optical sensor receives the light from the inner region and the light from the outer region of the subwavelength-based graded index structure.

19. The photo sensor pixel of claim 1 , wherein:
the subwavelength-based graded index structure comprises a graded index pattern, formed by a one-by-one alternating arrangement of grating structures and trenches, and that has a varied duty ratio that controls a local effective refractive index of the subwavelength-based graded index structure,
the active region is disposed between a first side of the peripheral region and a second side of the peripheral region, and
the varied duty ratio increases from an outer region of the subwavelength-based graded index structure towards an inner region of the subwavelength-based g

Assignees

• Infineon Technologies Ag

Inventors

• Kautzsch Thoralf
• Froehlich Heiko
• Stegemann Maik
• Vogt Mirko

Classifications

• H01L31/0203

  Electricity · mapped topic

• H01L31/02327 Primary

  Electricity · mapped topic

• H01L31/02016

  Electricity · mapped topic

• H10F77/95

  Circuit arrangements · CPC title

• H10F77/50

  Encapsulations or containers (for photovoltaic modules H10F19/80) · CPC title