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CN-122018083-A - Grating unit, grating array and grating coupler

CN122018083ACN 122018083 ACN122018083 ACN 122018083ACN-122018083-A

Abstract

The invention relates to the technical field of gratings, and discloses a grating unit, a grating array and a grating coupler, wherein the grating unit comprises a waveguide layer, a first groove body and a second groove body are arranged on the waveguide layer, the cross sections of the first groove body and the second groove body are quadrilateral, the depth of the first groove body is larger than that of the second groove body, and the distance between the first groove body and the second groove body is larger than the negative value of the preset distance. The invention realizes unidirectional radiation without a bottom reflector in the short-wave band grating coupler, inhibits downward radiation, has higher quality factor, and greatly reduces upper radiation efficiency loss in the mode field matching process.

Inventors

  • FAN YUAN
  • YU HAIHUA
  • YU HAO
  • PENG CHAO
  • WANG HAORAN
  • ZUO YI

Assignees

  • 北京联控前瞻技术有限公司
  • 北京大学

Dates

Publication Date
20260512
Application Date
20260310
Priority Date
20251212

Claims (9)

  1. 1. The utility model provides a grating unit, its characterized in that includes the waveguide layer, be equipped with first cell body and second cell body on the waveguide layer, first cell body with the cross section of second cell body is the quadrangle, the degree of depth of first cell body is greater than the degree of depth of second cell body, first cell body with the interval w3 of second cell body is greater than the negative value of predetermineeing the distance, predetermineeing the distance and satisfying: Wherein L is a preset distance, h2 is the depth of the second groove body, alpha 1 is the bottom angle of the second groove body, which is close to one side edge of the first groove body, and beta 2 is the bottom angle of the first groove body, which is close to one side edge of the second groove body.
  2. 2. The grating unit according to claim 1, wherein the structural parameters of the second groove body satisfy h2= (0.001-1) ×h1, w2= (0.001-5) ×h2, and w2 is the bottom edge length of the second groove body.
  3. 3. The grating unit of claim 1, wherein the waveguide layer has a thickness hw that satisfies hw= (1-10) x h1, where h1 is the depth of the first groove.
  4. 4. The grating unit according to claim 1, wherein the cross section of the first and/or second grooves is isosceles trapezoid, right trapezoid, rectangle, square or parallelogram.
  5. 5. The grating unit of claim 1, wherein a top edge length of the first groove and/or the second groove is greater than or equal to a bottom edge length.
  6. 6. A grating array comprising a plurality of grating elements according to any one of claims 1 to 5, wherein the plurality of grating elements are arranged in a first direction, wherein the first preset number of grating elements are arranged in the first direction, the bottom edge length of a first groove body is increased from a first initial value to a first target value, the bottom edge length of a second groove body is increased from a second initial value to a second target value, and the structural parameters of the grating elements arranged in the first preset number and the following are the same.
  7. 7. The grating array of claim 6, wherein the scatter angles of the preceding ones of the grating elements in the first direction increase from an initial scatter angle to a target scatter angle, the initial scatter angle and the target scatter angle satisfying: when theta >0, 0< theta0 and theta 1< 3 x theta; when theta <0, theta0<0 and theta 1. Gtoreq.3X theta; ; period1=A×B; wherein theta0 is an initial scattering angle, theta1 is a target scattering angle, theta is a preset grating scattering angle, As a wave vector of the wave, And the period1 is a first grating period, A is an adjustment coefficient, and B is the sum of the top edge length of the first groove body, the top edge length of the second groove body and the distance between the first groove body and the second groove body in the grating unit.
  8. 8. The grating array of claim 7, wherein a plurality of the grating elements are arranged in a first direction with a second grating period being a width of one of the grating elements, wherein the second grating period satisfies: period2=((lam+w1×(nwg-neff1)+w2×(nwg-neff2))/(nwg–nc×sin(theta))); Wherein period2 is the second grating period, w1 is the bottom edge length of the first groove body, w2 is the bottom edge length of the second groove body, lam is the wavelength of light, nwg is the effective refractive index of the waveguide layer, neff1 is the effective refractive index of the waveguide layer at the bottom edge depth position of the first groove body, neff2 is the effective refractive index of the waveguide layer at the bottom edge depth position of the second groove body, and nc is the refractive index of the upper cladding layer of the grating unit.
  9. 9. A grating coupler comprising a grating array according to any one of claims 6-9.

Description

Grating unit, grating array and grating coupler Technical Field The invention relates to the technical field of gratings, in particular to a grating unit, a grating array and a grating coupler. Background The cost of the mainstream long-wave band laser is far higher than that of the short-wave band laser, and along with the rapid development of short-distance optical interconnection, the short-wave band optical carrier wave shows negligible transmission loss and has great application potential. The grating coupler is a core interface for realizing the in-out of the optical signal inside and outside the optical chip, is limited by the optical bandwidth, and is not suitable for the input and output of the short-wave-band optical signal. At present, the existing short-band grating coupler generally adopts a traditional single-slot structure, and the coupling efficiency is low. Disclosure of Invention The invention provides a grating unit, a grating array and a grating coupler, which are used for solving the technical problem of low coupling efficiency of a short-wave-band grating coupler. In a first aspect, the present invention provides a grating unit, including a waveguide layer, where the waveguide layer is provided with a first slot body and a second slot body, the cross sections of the first slot body and the second slot body are quadrilateral, the depth of the first slot body is greater than that of the second slot body, the distance w3 between the first slot body and the second slot body is greater than the negative value of a preset distance, and the preset distance satisfies: Wherein L is a preset distance, h2 is the depth of the second groove body, alpha 1 is the bottom angle of the second groove body close to one side edge of the first groove body, and beta 2 is the bottom angle of the first groove body close to one side edge of the second groove body. In some embodiments, the structural parameters of the second groove body satisfy h2= (0.001-1) ×h1, and w2= (0.001-5) ×h2, where w2 is the bottom edge length of the second groove body. In some embodiments, the thickness hw of the waveguide layer satisfies hw= (1-10) ×h1, where h1 is the depth of the first groove. In some embodiments, the cross-section of the first channel and/or the second channel is isosceles trapezoid, right trapezoid, rectangle, square, or parallelogram. In some embodiments, the top edge length of the first channel and/or the second channel is greater than or equal to the bottom edge length. In a second aspect, the present invention provides a grating array, including a plurality of grating units according to any one of the first aspect of the present invention, wherein the plurality of grating units are arranged along a first direction, and the bottom edge length of the first groove body is increased from a first initial value to a first target value in a first preset number of grating units arranged in front, the bottom edge length of the second groove body is increased from a second initial value to a second target value, and the structural parameters of the grating units arranged in front and behind the first preset number are the same. In some embodiments, the scatter angles of the preceding number of grating elements ordered in the first direction are incremented from an initial scatter angle to a target scatter angle, the initial scatter angle and the target scatter angle satisfying: when theta >0, 0< theta0 and theta 1< 3 x theta; when theta <0, theta0<0 and theta 1. Gtoreq.3X theta; ; period1=A×B; wherein theta0 is an initial scattering angle, theta1 is a target scattering angle, theta is a preset grating scattering angle, As a wave vector of the wave,The period1 is the first grating period, A is the adjustment coefficient, and B is the sum of the top edge length of the first groove body, the top edge length of the second groove body and the distance between the first groove body and the second groove body in the grating unit. In some embodiments, the plurality of grating units are arranged along the first direction with a width of one grating unit of a second grating period, wherein the second grating period satisfies: period2=((lam+w1×(nwg-neff1)+w2×(nwg-neff2))/(nwg–nc×sin(theta))); Wherein period2 is the second grating period, w1 is the bottom edge length of the first groove, w2 is the bottom edge length of the second groove, lam is the wavelength of light, nwg is the effective refractive index of the waveguide layer, neff1 is the effective refractive index of the waveguide layer at the bottom edge depth position of the first groove, neff2 is the effective refractive index of the waveguide layer at the bottom edge depth position of the second groove, nc is the refractive index of the upper cladding layer of the grating unit. In a third aspect, the invention provides a grating coupler comprising a grating array according to any of the second aspects of the invention. The invention has the following beneficial effects: A