Passive fiber coupler with UV windows

Patent metadata

Field	Value
Publication number	US-10527790-B2
Application number	US-201715841005-A
Country	US
Kind code	B2
Filing date	Dec 13, 2017
Priority date	Dec 13, 2017
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

Embodiments herein describe a fiber array unit (FAU) configured to couple a photonic chip with a plurality of optical fibers. Epoxy can be used to bond the FAU to the photonic chip. However, curing the epoxy between the FAU and the photonic chip is difficult. As such, the FAU can include one or more optical windows etched into a non-transparent layer that overlap with epoxy wells in the photonic chip. Moreover, the FAU may include a transparent substrate on which the non-transparent layer is disposed that permits UV light to pass therethrough. As such, during curing, UV light can be pass through the transparent substrate and through the optical windows in the non-transparent layer to cure the epoxy disposed between the FAU and the photonic chip.

First claim

We claim:

1. A method, comprising:
disposing epoxy into an epoxy well in a photonic chip;
aligning an optical interface of the photonic chip to an optical fiber mounted on a fiber array unit (FAU), wherein the FAU comprises a first layer disposed on a transparent substrate, wherein the first layer comprises an optical window, and wherein the transparent substrate and the optical window are disposed over the epoxy well when the optical fiber is aligned to the optical interface; and
curing the epoxy by passing electromagnetic radiation through the transparent substrate and the optical window to reach the epoxy well, wherein the curing is performed after aligning the optical interface to the optical fiber.

2. The method of claim 1 , wherein the photonic chip comprises an alignment slot formed on a same surface as the epoxy well, wherein aligning the optical interface to the optical fiber comprises:
urging an alignment feature disposed on the first layer in the FAU into the alignment slot thereby passively aligning the optical fiber to the optical interface.

3. The method of claim 1 , further comprising, before aligning the optical fiber to the optical interface:
disposing an index matching epoxy on the optical interface.

4. The method of claim 1 , wherein the first layer comprises a material that is not transparent to the electromagnetic radiation, wherein the optical window forms an aperture in the material in the first layer thereby exposing the transparent substrate.

5. The method of claim 4 , wherein the material of the first layer is crystalline silicon and a material of the transparent substrate is silicon dioxide.

6. The method of claim 1 , further comprising:
forming a groove in the first layer and the optical window in a same etching step; and
mounting the optical fiber into the groove.

7. The method of claim 6 , wherein the groove is a U-groove where a bottom surface of the U-groove is the transparent substrate.

8. The method of claim 6 , wherein the groove is a V-groove, wherein the V-groove does not contact the transparent substrate.

9. An optical system, comprising:
a photonic chip, comprising:
a waveguide,
an optical interface optically coupled to the waveguide, and
an epoxy well; and

a fiber array unit (FAU) coupled with the photonic chip using cured epoxy in the epoxy well, comprising:
a transparent substrate,
a first layer disposed on the transparent substrate, the first layer comprising an optical window and a groove,
an optical fiber disposed in the groove and aligned to the optical interface in the photonic chip, and
a lid, wherein the optical fiber is disposed between the lid and the transparent substrate,
wherein the transparent substrate and the optical window are disposed over the epoxy well.

10. The optical system of claim 9 , wherein the photonic chip further comprises a first alignment feature disposed on a same surface as the epoxy well and the FAU comprises a second alignment feature disposed on the first layer, wherein the first and second alignment features are arranged such that when mated, the optical fiber is passively aligned to the optical interface.

11. The optical system of claim 9 , wherein the optical fiber is directly optically connected to the optical interface with an index matching epoxy disposed between the optical fiber and the optical interface.

12. The optical system of claim 9 , wherein the first layer comprises a material that blocks ultra violet (UV) light, wherein the optical window forms an aperture in the material thereby exposing the transparent substrate, wherein a material of the transparent substrate is transparent to UV light.

13. The optical system of claim 12 , wherein the material of the first layer is crystalline silicon and the material of the transparent substrate is silicon dioxide.

14. The optical system of claim 9 , wherein the photonic chip comprises a waveguide adapter, wherein a first end of the waveguide adapter forms at least a part of the optical interface and a second, opposite end of the waveguide adapter is optically coupled to the waveguide, wherein the waveguide adapter is configured to adjust a mode size of optical signals transferred between the waveguide and the optical fiber.

15. The optical system of claim 14 , wherein the epoxy well extends through a second layer in the photonic chip containing the waveguide adapter.

16. A fiber array unit (FAU), comprising:
a transparent substrate;
a first layer disposed on the transparent substrate, wherein a material of the transparent substrate is transparent to UV light while a material of the first layer blocks UV light;
an optical window in the first layer, wherein the transparent substrate is one side of the optical window;
a groove formed in the first layer; and
an optical fiber disposed in the groove and terminates before reaching the optical window, wherein a first portion of the transparent substrate extends beyond a termination end of the optical fiber, wherein the optical window is disposed on the first portion of the transparent substrate.

17. The FAU of claim 16 , further comprising:
a plurality of alignment features formed on the first layer, wherein the plurality of alignment features are disposed over the first portion of the transparent substrate.

18. The FAU of claim 16 , wherein a thickness of the first layer is less than a distance from a core in the optical fiber to the transparent substrate.

19. The FAU of claim 16 , wherein at least one of (i) the material of the first layer is crystalline silicon and the material of the transparent substrate is silicon dioxide, and (ii) the material of the transparent substrate is a transparent molded material.

20. The FAU of claim 16 , further comprising:
a plurality of parallel grooves formed in the first layer; and
a fiber stop formed in the first layer, wherein the fiber stop contacts termination ends of optical fibers disposed in the plurality of parallel grooves, wherein the fiber stop is between the plurality of parallel grooves and the optical window.

Assignees

• Cisco Tech Inc

Inventors

• Potluri Kumar Satya Harinadh
• Maker Ashley J
• Patel Vipulkumar

Classifications

• G02B6/30

  for use between fibre and thin-film device · CPC title

• G02B6/4212

  the intermediate optical element being a coupling medium interposed therebetween, e.g. epoxy resin, refractive index matching material, index grease, matching liquid or gel · CPC title

• G02B6/4244

  Mounting of the optical elements · CPC title

• G02B6/1225 Primary

  comprising photonic band-gap structures or photonic lattices · CPC title

• G02B6/4239

  Adhesive bonding; Encapsulation with polymer material · CPC title