US 12,030,804 B2
Optical fiber
Yoshiaki Tamura, Osaka (JP); Hirotaka Sakuma, Osaka (JP); and Akiko Funakoshi, Osaka (JP)
Assigned to SUMITOMO ELECTRIC INDUSTRIES, LTD., Osaka (JP)
Filed by SUMITOMO ELECTRIC INDUSTRIES, LTD., Osaka (JP)
Filed on Jan. 25, 2021, as Appl. No. 17/156,862.
Application 17/156,862 is a continuation of application No. PCT/JP2019/029691, filed on Jul. 29, 2019.
Claims priority of application No. 2018-143933 (JP), filed on Jul. 31, 2018.
Prior Publication US 2021/0171390 A1, Jun. 10, 2021
Int. Cl. G02B 6/38 (2006.01); C03C 13/04 (2006.01); G02B 6/02 (2006.01)
CPC C03C 13/046 (2013.01) [G02B 6/02 (2013.01)] 8 Claims
OG exemplary drawing
 
1. An optical fiber comprising:
a core; and
a cladding that surrounds the core,
wherein the core and cladding are respectively formed from silica glass containing a dopant composed of an alkali metal element or an alkaline-earth metal element,
a relative refractive index difference Δ defined by Expression (1):
Δ[%]=100×(n12−n22)/2n02  (1)
is 0.2% or higher, where n0 denotes a refractive index of silica glass that does not contain the dopant, n1 denotes a refractive index of the core, and n2 denotes a refractive index of the cladding, and
a ratio of a maximum value of a concentration of the alkali metal element or the alkaline-earth metal element in the cladding to a maximum value of a concentration of the alkali metal element or the alkaline-earth metal element in the core is 0.06 or higher and 0.25 or lower.