US 12,140,795 B2
Optical 2D spot-size conversion
Timo Aalto, Espoo (FI)
Assigned to Teknologian tutkimuskeskus VTT Oy, Espoo (FI)
Appl. No. 17/786,553
Filed by Teknologian tutkimuskeskus VTT Oy, Espoo (FI)
PCT Filed Dec. 18, 2020, PCT No. PCT/FI2020/050856
§ 371(c)(1), (2) Date Jun. 17, 2022,
PCT Pub. No. WO2021/123505, PCT Pub. Date Jun. 24, 2021.
Claims priority of application No. 20196094 (FI), filed on Dec. 18, 2019.
Prior Publication US 2023/0030105 A1, Feb. 2, 2023
Int. Cl. G02B 6/122 (2006.01); G02B 6/12 (2006.01); G02B 6/125 (2006.01); G02B 6/126 (2006.01); G02B 6/14 (2006.01)
CPC G02B 6/1228 (2013.01) [G02B 6/125 (2013.01); G02B 6/126 (2013.01); G02B 6/14 (2013.01); G02B 2006/12152 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An optical assembly for realizing horizontal and vertical spot-size conversion to couple light between an expanded end of a first thin waveguide to one end of a second thick waveguide, said assembly comprising:
at least one first thin waveguide with a first section having a first optical mode field and a horizontal spot-size expansion section providing spot-size conversion for a first horizontal dimension of said first optical mode field of a light beam propagating in said first thin waveguide; and
at least one second thick waveguide with a second section having a second optical mode field and a horizontal spot-size reduction section providing spot-size conversion for a second horizontal dimension of said second optical mode field of a light beam propagating in said second thick waveguide; wherein
the expanded end of said first thin waveguide is aligned and rotated to interface with said one end of said second thick waveguide, so that the polarization of the light beam in said first thin and second thick waveguides is rotated 90 degrees with respect to each other, whereby the spot size of a light beam so coupled between the first thin and second thick waveguides is expanded or shrunk in both transverse dimensions, depending on the direction of the light beam.