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CN-121995571-A - Spot size converter comprising a two-dimensional bi-anisotropic sub-wavelength grating structure

CN121995571ACN 121995571 ACN121995571 ACN 121995571ACN-121995571-A

Abstract

The present disclosure relates to spot-size converters comprising two-dimensional bi-anisotropic sub-wavelength grating structures. In some embodiments, a Photonic Integrated Circuit (PIC) may include a spot-size converter (SSC). The SSC can include a tapered waveguide having a length along a first direction and a width along a second direction. The first direction may be parallel to the propagation direction and the second direction may be perpendicular to the propagation direction. The SSC may include a two-dimensional (2D) bi-anisotropic sub-wavelength grating (SWG) structure. A portion of the 2D dual anisotropic SWG structure may surround a portion of the tapered waveguide in the second direction along the first direction.

Inventors

  • M. B. Mia
  • K. A. Macquarie

Assignees

  • 朗美通经营有限责任公司

Dates

Publication Date
20260508
Application Date
20250929
Priority Date
20241223

Claims (20)

  1. 1. A Photonic Integrated Circuit (PIC) comprising a spot-size converter SSC, the SSC comprising: A tapered waveguide having a length along a first direction and a width along a second direction, Wherein the first direction is parallel to the propagation direction and the second direction is perpendicular to the propagation direction, and A two-dimensional 2D dual anisotropic sub-wavelength grating SWG structure, wherein a portion of the 2D dual anisotropic SWG structure surrounds a portion of the tapered waveguide in the second direction and along the first direction.
  2. 2. The PIC of claim 1, wherein a periodicity of grating elements of the 2D dual anisotropic SWG structure along the first direction is different than a periodicity of the grating elements of the 2D dual anisotropic SWG structure along the second direction.
  3. 3. The PIC of claim 1, wherein a periodicity of grating elements of the 2D dual anisotropic SWG structure along the first direction matches a periodicity of the grating elements of the 2D dual anisotropic SWG structure along the second direction.
  4. 4. The PIC of claim 1, wherein a filling rate of grating elements of the 2D dual-anisotropic SWG structure along the first direction is different than a filling rate of the grating elements of the 2D dual-anisotropic SWG structure along the second direction.
  5. 5. The PIC of claim 1, wherein a filling rate of grating elements of the 2D dual-anisotropic SWG structure along the first direction matches a filling rate of the grating elements of the 2D dual-anisotropic SWG structure along the second direction.
  6. 6. The PIC of claim 1, wherein one or more of the grating elements of the 2D dual anisotropic SWG structure have a rectangular shape, an elliptical shape, or a trapezoidal shape.
  7. 7. The PIC of claim 1, wherein a size of a grating element is based on a wavelength range associated with the SSC.
  8. 8. The PIC of claim 1, wherein grating elements of the 2D dual anisotropic SWG structure are symmetrically distributed along the tapered waveguide and extend along the first direction.
  9. 9. The PIC of claim 1, wherein a dielectric constant of the dual anisotropic SWG structure along the first direction is different from a dielectric constant of the dual anisotropic SWG structure along the second direction.
  10. 10. The PIC of claim 1, wherein a dielectric constant of the dual anisotropic SWG structure along a third direction is different from a dielectric constant of the dual anisotropic SWG structure along the first direction and a dielectric constant of the dual anisotropic SWG structure along the second direction.
  11. 11. The PIC of claim 1, wherein a height of a grating element of the 2D dual anisotropic SWG structure is different from a height of the tapered waveguide.
  12. 12. The PIC of claim 1, wherein a height of a grating element of the 2D dual anisotropic SWG structure matches a height of the tapered waveguide.
  13. 13. The PIC of claim 1, wherein the tapered waveguide comprises at least one of silicon or silicon nitride.
  14. 14. The PIC of claim 1, wherein the tapered waveguide is a segmented waveguide.
  15. 15. The PIC of claim 1, wherein the 2D dual anisotropic SWG structure comprises silicon grating elements surrounded by one or more of silicon dioxide, an index matching fluid, or air.
  16. 16. The PIC of claim 1, wherein the 2D dual anisotropic SWG structure comprises a silicon nitride grating element surrounded by one or more of silicon dioxide, an index matching fluid, or air.
  17. 17. The PIC of claim 1, wherein a periodicity of grating elements of the 2D dual-anisotropic SWG structure along the first direction and the periodicity of the grating elements of the 2D dual-anisotropic SWG structure along the second direction is less than about Wherein Is an operable wavelength associated with the SSC, and n is the refractive index of the 2D dual anisotropic SWG structure.
  18. 18. The PIC of claim 1, wherein grating elements of the 2D dual anisotropic SWG structure are oriented at 90 ° relative to the propagation direction.
  19. 19. The PIC of claim 1, wherein grating elements of the 2D dual anisotropic SWG structure are oriented at any angle relative to the propagation direction.
  20. 20. The PIC of claim 1, wherein grating elements of the 2D dual anisotropic SWG structure are arranged in a gaussian, linear, apodized, or parabolic pattern relative to a plane defined by the first and second directions.

Description

Spot size converter comprising a two-dimensional bi-anisotropic sub-wavelength grating structure Cross Reference to Related Applications The present patent application claims priority from U.S. provisional application No. 63/717,650 filed on 7/11/2024 and entitled "mode size converter (MODE SIZE CONVERTER INCLUDING SUBWAVELENGTH GRATING METAMATERIALS) comprising sub-wavelength grating metamaterials". The disclosure of the prior application is considered to be part of the present patent application and is incorporated by reference. Technical Field The present disclosure relates generally to a spot-size converter (SSC) and SSC comprising a two-dimensional (2D) bi-anisotropic sub-wavelength grating (SWG) structure. Background SSC is an optical device that can be used to achieve fiber-to-chip coupling by matching the mode field diameter (also referred to as the spot size) of the fiber to the mode size of the photonic waveguide on the integrated chip. The mode field diameter of a standard single mode fiber (e.g., in the range of about 8 micrometers (μm) to about 10 μm at a wavelength of 1550 nanometers (nm)) is significantly larger than the mode size in the waveguide on the photonic chip (e.g., in the range of about 0.5 μm to about 2 μm). Without SSC, there will be a significant mismatch between the fiber and the field distribution of the waveguide mode, resulting in low coupling efficiency and higher insertion loss. SSC is used to reduce this mismatch and thereby improve power transfer between the fiber and the waveguide. The improved pattern matching provided by SSCs can also reduce back reflection that would otherwise degrade the performance of the optical system. Disclosure of Invention In some embodiments, a Photonic Integrated Circuit (PIC) including an SSC includes a tapered waveguide having a length along a first direction and a width along a second direction, wherein the first direction is parallel to the propagation direction and the second direction is perpendicular to the propagation direction, and a 2D dual-anisotropic SWG structure, wherein a portion of the 2D dual-anisotropic SWG structure surrounds a portion of the tapered waveguide along the first direction in the second direction. In some embodiments, a PIC comprising an SSC includes a first section comprising a first portion of a tapered waveguide, a second section comprising a second portion of the tapered waveguide and a first portion of a dual anisotropic SWG structure (comprising a plurality of grating elements), wherein the second portion of the dual anisotropic SWG structure surrounds the second portion of the tapered waveguide along a length of the second section, and a third section comprising the second portion of the dual anisotropic SWG structure. In some embodiments, a PIC including an SSC includes a waveguide having a length along a first direction and a width along a second direction perpendicular to the first direction, and a 2D dual-anisotropic SWG structure surrounding a portion of the tapered waveguide along the first direction, wherein a dielectric constant of the dual-anisotropic SWG structure relative to the first direction is different from a dielectric constant of the dual-anisotropic SWG structure relative to the second direction, and wherein a dielectric constant of the dual-anisotropic SWG structure relative to the third direction is different from a dielectric constant of the dual-anisotropic SWG structure relative to the first direction and a dielectric constant of the dual-anisotropic SWG structure relative to the second direction. Drawings Fig. 1A-1B are diagrams illustrating example embodiments of SSCs including the 2D dual anisotropic SWG structures described herein. Fig. 2 is a diagram illustrating grating elements of a 2D dual anisotropic SWG structure described herein distributed along a propagation direction based on a gaussian distribution. Fig. 3-6 are diagrams illustrating simulation results associated with various example embodiments of SSCs including the 2D dual anisotropic SWG structures described herein. Fig. 7-12 are graphs illustrating simulation results illustrating the effects of different parameter variations associated with SSCs comprising the 2D dual anisotropic SWG structures described herein. Fig. 13-14 are graphs illustrating simulation results illustrating insertion loss and PDL associated with SSC including the 2D dual anisotropic SWG structures described herein. Detailed Description The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. Note that references herein to alphabetically designated optical bands (e.g., O-band, C-band, L-band, etc.) refer to the International Telecommunications Union (ITU) optical band in the near infrared. Fiber-to-chip coupling is a challenge with respect to the development of silicon photonics-based devices, which are an in