Dump terminator

Patent metadata

Field	Value
Publication number	US-10989874-B2
Application number	US-201916698156-A
Country	US
Kind code	B2
Filing date	Nov 27, 2019
Priority date	Jan 24, 2019
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

When routing light on photonic integrated circuit (PIC) chips optical back-reflection and scattering can be highly detrimental to the desired application. Unused ports of optical devices, such as MMI, DC, Y-junction, PD, etc. are a cause for back-reflection and scattering, whereby the scattered light could get picked up by adjacent components, e.g. photodetectors. Management of stray light on the PIC is needed to prevent the undesired coupling between various components and to reduce noise. A dump taper may be used to guide and scatter stray light away from sensitive components or fully absorb the light while maintaining very low reflection from the taper. A doped dump taper may be used to passively absorb light reaching the unused port, thereby eliminating unwanted reflection and scattering. Alternatively, an undoped taper may be used to scatter light away from sensitive components while maintaining very low back-reflection.

First claim

We claim:

1. A dump terminator device configured to be coupled to a waveguide for minimizing back reflection of light into an optical system, comprising:
a tapering waveguide section, tapering from an inner wider end proximate the waveguide to an outer thinner outer free end, whereby an effective index of the tapering waveguide section gradually decreases and adiabatically transforms the light from a guided waveguide mode into a leaky mode in cladding surrounding the tapering waveguide section;
wherein the tapering waveguide section comprises a doped waveguide section comprising either positive or negative dopants for increasing an absorption coefficient of the doped waveguide section.

2. The device according to claim 1 , wherein the tapering waveguide section comprises a rib waveguide.

3. The device according to claim 2 , further comprising a doped cladding section surrounding the tapering waveguide section.

4. The device according to claim 3 , wherein the tapering waveguide section includes a subwavelength grating section surrounded by the doped cladding section, in which a fill ratio of waveguide material to cladding material is gradually decreased from an inner end closest to the waveguide to an outer free end for transmitting a propagating mode into the doped cladding section.

5. The device according to claim 2 , wherein the tapering waveguide section includes a subwavelength grating section surrounded by the cladding, in which a fill ratio of waveguide material to cladding material is gradually decreased from an inner end closest to the waveguide to an outer free end for transmitting a propagating mode into the cladding.

6. The device according to claim 1 , further comprising a doped cladding section surrounding the doped waveguide section.

7. The device according to claim 6 , wherein the tapering waveguide section includes a subwavelength grating section surrounded by the cladding, in which a fill ratio of waveguide material to cladding material is gradually decreased from an inner end closest to the waveguide to an outer free end for transmitting a propagating mode into the cladding.

8. The device according to claim 1 , wherein the tapering waveguide section includes a subwavelength grating section surrounded by the cladding, in which a fill ratio of waveguide material to cladding material is gradually decreased from an inner end closest to the waveguide to an outer free end for transmitting a propagating mode into the cladding.

9. The device according to claim 1 ,
wherein the dump terminator comprises an optically absorbing enclosure on either side of the tapering waveguide section; and
wherein the optically absorbing enclosure comprises germanium.

10. The device according to claim 1 , wherein the doped waveguide section of the tapering waveguide section includes 1×10 18 cm −3 dopant concentration.

11. The device according to claim 1 ,
wherein the dump terminator further comprises a bend section redirecting a propagation direction away from the optical system.

12. The device according to claim 1 , wherein the tapering waveguide section is 15 μm to 150 μm long.

13. A dump terminator device configured to be coupled to a waveguide for minimizing back reflection of light into an optical system, comprising:
a tapering waveguide section, tapering from an inner wider end proximate the waveguide to an outer thinner outer free end, whereby an effective index of the tapering waveguide section gradually decreases and adiabatically transforms the light from a guided waveguide mode into a leaky mode in cladding surrounding the tapering waveguide section;
wherein the tapering waveguide section comprises a rib waveguide;
wherein the dump terminator comprises an optically absorbing enclosure on either side of the tapering waveguide section; and
wherein the optically absorbing enclosure comprises germanium.

14. The device according to claim 13 , wherein the tapering waveguide section comprises a doped waveguide section comprising either positive or negative dopants for increasing an absorption coefficient of the doped waveguide section while minimizing an index difference between the doped waveguide section and an undoped region.

15. The device according to claim 13 , wherein the tapering waveguide section includes a subwavelength grating section surrounded by the cladding, in which a fill ratio of waveguide material to cladding material is gradually decreased from an inner end closest to the waveguide to an outer free end for transmitting a propagating mode into the cladding.

16. A dump terminator device configured to be coupled to a waveguide for minimizing back reflection of light into an optical system, comprising:
a tapering waveguide section, tapering from an inner wider end proximate the waveguide to an outer thinner outer free end, whereby an effective index of the tapering waveguide section gradually decreases and adiabatically transforms the light from a guided waveguide mode into a leaky mode in cladding surrounding the tapering waveguide section;
wherein the tapering waveguide section comprises a subwavelength grating section surrounded by the cladding, in which a fill ratio of waveguide material to cladding material is gradually decreased from an inner end closest to the waveguide to an outer free end for transmitting a propagating mode into the cladding.

17. The device according to claim 16 , further comprising an optically absorbing enclosure on either side of the tapering waveguide section.

18. The device according to claim 17 , wherein the optically absorbing enclosure comprises germanium.

19. The device according to claim 16 , wherein the tapering waveguide section includes a doped waveguide section comprising either positive or negative dopants for increasing an absorption coefficient of the doped waveguide section while minimizing an index difference between the doped waveguide section and an undoped region.

20. The device according to claim 16 , further comprising a doped cladding section surrounding the tapering waveguide section.

Assignees

• Elenion Tech Llc

Inventors

• Liu Yang
• Shi Ruizhi
• Galfsky Tal

Classifications

• G02B5/1809 Primary

  with pitch less than or comparable to the wavelength · CPC title

• H01S3/0064

  Anti-reflection devices, e.g. optical isolaters (absorbing layers for marking or protecting purposes in laser working B23K26/50; magneto-optical non-reciprocal devices G02F1/093, G02F1/0955) · CPC title

• G02B5/18

  Diffraction gratings {(holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44)} · CPC title

• G02B6/124

  Geodesic lenses or integrated gratings · CPC title

• G02B6/241

  Light guide terminations · CPC title