US 12,259,579 B1
Single photon interconnect employing low index cladding spot size converter
Eric Dudley, Sacramento, CA (US); Stanley Burgos, Campbell, CA (US); and Jin Yao, San Diego, CA (US)
Assigned to PsiQuantum, Corp., Palo Alto, CA (US)
Filed by PsiQuantum, Corp., Palo Alto, CA (US)
Filed on Jun. 10, 2022, as Appl. No. 17/806,338.
Claims priority of provisional application 63/202,433, filed on Jun. 10, 2021.
Int. Cl. G02B 6/30 (2006.01)
CPC G02B 6/305 (2013.01) 20 Claims
OG exemplary drawing
 
1. A device comprising:
a substrate including an optical fiber alignment structure formed thereon; and
a spot size converter on the substrate and aligned with the optical fiber alignment structure, the spot size converter having a first end and a second end and including:
a first cladding layer characterized by a first refractive index, wherein at least a portion of the first cladding layer is tapered such that a first width of a first end of the first cladding layer at the first end of the spot size converter is smaller than a second width of the first cladding layer at the second end of the spot size converter;
a waveguide core in the first cladding layer, wherein the waveguide core is tapered and has a first cross-section of a first end of the waveguide core at the first end of the spot size converter and a second cross-section at the second end of the spot size converter, the first cross-section being smaller than the second cross-section;
a second cladding layer surrounding the first cladding layer, the second cladding layer having a second refractive index lower than the first refractive index of the first cladding layer; and
a heater configured to tune the second refractive index of the second cladding layer, thereby tuning a refractive index difference between the first cladding layer and the second cladding layer,
wherein the first end of the first cladding layer is aligned with the first end of the waveguide core.