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CN-122029476-A - Photonic circuit and method of manufacturing the same

CN122029476ACN 122029476 ACN122029476 ACN 122029476ACN-122029476-A

Abstract

A photonic circuit (200) is fabricated by adding hydrogenated amorphous silicon strips (107) on top of an optically functional layer (104) supported by a substrate (105). The thickness of the optically functional layer (104) is between 100nm and 500 nm. The hydrogenated amorphous silicon has a refractive index higher than that of the optically functional layer (104). A protective layer (106) may be deposited on the optically functional layer (104) prior to adding the hydrogenated amorphous silicon strips (107).

Inventors

  • H. Nick Bucket
  • B. Van Someren

Assignees

  • 瑞普光子技术有限公司

Dates

Publication Date
20260512
Application Date
20241017
Priority Date
20231017

Claims (20)

  1. 1. A method of manufacturing a photonic circuit (200, 400), the method comprising: On top of an optical functional layer (104) supported by a substrate (105) is added a stripe (107) of hydrogenated amorphous silicon, the thickness of the optical functional layer (104) being between 100nm and 500nm, the refractive index of the hydrogenated amorphous silicon being higher than the refractive index of the optical functional layer.
  2. 2. The method of manufacturing a photonic circuit according to claim 1, wherein the hydrogenated amorphous silicon strips (107) have a thickness of less than 50nm.
  3. 3. A method of manufacturing a photonic circuit according to claim 1 or 2, comprising before adding the hydrogenated amorphous silicon strips (107) on top of the optically functional layer (104): A protective layer (106) is deposited over the optically functional layer.
  4. 4. A method of manufacturing a photonic circuit according to claim 3, wherein the protective layer (106) has a refractive index lower than the refractive index of the optically functional layer (104).
  5. 5. A method of manufacturing a photonic circuit according to claim 4, wherein the thickness of the protective layer (106) is less than 50nm.
  6. 6. A method of manufacturing a photonic circuit according to claim 5, wherein the thickness of the protective layer (106) is greater than 3nm.
  7. 7. A method of manufacturing a photonic circuit according to any of claims 3 to 6, wherein the protective layer (106) comprises at least one of silicon nitride, aluminium oxide, nickel oxide and chromium oxide.
  8. 8. The method of manufacturing a photonic circuit according to any of claims 3 to 7, wherein after adding the hydrogenated amorphous silicon stripes (107), the protective layer (106) is removed in areas adjacent to the hydrogenated amorphous silicon stripes.
  9. 9. The method of manufacturing a photonic circuit according to any one of claims 1 to 8, wherein the refractive index of the optically functional layer (104) varies with the amplitude of the electric field.
  10. 10. A method of manufacturing a photonic circuit according to claim 9, wherein the polarization density in the optically functional layer (104) varies non-linearly with the amplitude of the electric field.
  11. 11. The method of manufacturing a photonic circuit according to claim 10, wherein the optically functional layer (104) comprises at least one of lithium niobate, barium titanate, potassium niobate and a material with the acronym KTN.
  12. 12. The method of manufacturing a photonic circuit according to any one of claims 1 to 11, wherein adding the hydrogenated amorphous silicon stripes (107) on top of the optically functional layer (104) comprises: adding a hydrogenated amorphous silicon layer on top of the optically functional layer, and The hydrogenated amorphous silicon layer is etched to form the hydrogenated amorphous silicon strips.
  13. 13. A photonic circuit (200, 400) obtained by the method according to any one of claims 1 to 12, wherein the optically functional layer (104) and the hydrogenated amorphous silicon strips (107) on top thereof together form a waveguide (303) for a photonic signal having a wavelength in vacuum.
  14. 14. The photonic circuit of claim 13, wherein the width of the hydrogenated amorphous silicon strips (107) is smaller than the wavelength of the photonic signal in a vacuum.
  15. 15. The photonic circuit of claim 14, wherein the width of the hydrogenated amorphous silicon strips (107) is greater than one tenth of the wavelength of the photonic signal in a vacuum.
  16. 16. The photonic circuit of any of claims 13 to 15, wherein the hydrogenated amorphous silicon strips (107) have a cross-sectional area smaller than 2/7 Of which Is the wavelength in the vacuum divided by the mode index of the photon signal.
  17. 17. The photonic circuit according to any one of claims 13 to 16, wherein the thickness of the optically functional layer (104) is less than one third of the wavelength of the photonic signal in a vacuum.
  18. 18. The photonic circuit according to any one of claims 13 to 17, wherein the thickness of the optically functional layer (104) is greater than one twentieth of the wavelength of the photonic signal in a vacuum.
  19. 19. A photonic system comprising: the photonic circuit (601) according to any one of claims 13 to 18; -a discrete waveguide (602), wherein the discrete waveguide (602) is located outside the photonic circuit; an optical coupler (604) disposed between a waveguide (603) in the photonic circuit and the discrete waveguide, wherein the optical coupler comprises a cylindrical lens (605).
  20. 20. The photonic system of claim 19, wherein the cylindrical lens (605) is included in the photonic circuit (601).

Description

Photonic circuit and method of manufacturing the same Technical Field One aspect of the application relates to a method of manufacturing a photonic circuit. The fabrication of photonic circuits may involve materials such as lithium niobate, barium titanate, or other materials with refractive indices that vary with the magnitude of the electric field. Other aspects of the application relate to a photonic circuit and a photonic system. Background Photonic circuits typically include an optical functional layer upon which other elements may be added to form functional components for photonic signal processing. For example, the waveguides may be formed by adding strips of material on the optically functional layer that have an appropriate refractive index and thickness relative to the optically functional layer. The strip of material may be added using, for example, photolithographic techniques. The optically functional layer of the photonic circuit may comprise a material having a refractive index that varies with the magnitude of the electric field. This enables the photonic circuit to actively process the photonic signal (similar to an electrical integrated circuit that processes electrical signals), but at significantly higher speeds. This makes photonic circuits particularly suitable for applications requiring fast processing, such as quantum computing and artificial intelligence. For efficient processing of photon signals, it is desirable that the optical functional layer have a relatively high pockels coefficient (Pockels coefficient). The higher the pockels cell, the greater the degree to which the refractive index changes with the electric field. Certain oxide-based crystals (oxides-based crystals) have a relatively high pockels coefficient. These include, for example, lithium niobate (LiNbO 3), barium titanate (BaTiO 3), potassium niobate (KNbO 3), and materials with the acronym KTN. Thus, the optically functional layer may comprise at least one of the above mentioned materials. However, materials with relatively high pockels coefficients are often difficult to process. First, these materials are difficult to etch. Such etching difficulties can lead to significant sidewall roughness, which can adversely affect optical signal processing due to, for example, scattering. In addition, these materials are susceptible to degradation during processing, such as chemical composition changes or surface roughness increases due to unwanted chemical reactions, or both. This reduces the pockels cell and adversely affects other optical properties. All of this makes the manufacture of photonic circuits complex and costly. Low cost, mass production of photonic circuits has not been achieved. Yet another factor has prevented low cost, mass production of photonic circuits. Materials with relatively high pockels coefficients are generally not acceptable to semiconductor manufacturers. This is because these materials can contaminate equipment used to fabricate semiconductor circuits, particularly CMOS type semiconductor circuits. Unless cleaned, this can make these devices unsuitable for fabricating semiconductor circuits. In particular, lithium and barium can have deleterious effects on semiconductor manufacturing equipment. Patent publication WO2022248037A1 describes a strip-loaded optical waveguide comprising a slab section (slab section) and a strip section. The strip portion is disposed on or over the plate portion to define a light confinement region in the plate portion and the strip portion. The refractive index of the strip portion is lower than that of the plate portion. The strap portion is made of a polymeric material. Disclosure of Invention There is a need for a photonic circuit fabrication technique that provides improvements in at least one of manufacturing cost, manufacturing yield, and manufacturing quality, particularly in terms of photonic circuit performance. One aspect of the application relates to a method of manufacturing a photonic circuit. The method comprises the following steps: On top of the optically functional layer supported by the substrate, strips of hydrogenated amorphous silicon are added, which have a refractive index higher than that of the optically functional layer. Another aspect of the application relates to a photonic circuit obtained by the above method, wherein the optically functional layer and the hydrogenated amorphous silicon strips on top of it together form a waveguide for a photonic signal having a wavelength in vacuum. Yet another aspect of the application relates to a photonic system comprising an optical coupler arranged between a waveguide in a photonic circuit as defined above and a discrete waveguide (discrete waveguide), the optical coupler comprising a cylindrical lens. In each of these aspects, there is no need to etch the optically functional layer to form the waveguide. The waveguide is formed by adding a hydrogenated amorphous silicon stripe to the optically f