US 12,405,418 B2
Multicore optical fiber, method of designing multicore optical fiber, and optical transmission method
Takashi Matsui, Musashino (JP); and Kazuhide Nakajima, Musashino (JP)
Assigned to Nippon Telegraph and Telephone Corporation, Tokyo (JP)
Filed by Nippon Telegraph and Telephone Corporation, Tokyo (JP)
Filed on Dec. 21, 2023, as Appl. No. 18/392,976.
Application 18/392,976 is a continuation of application No. 17/294,892, granted, now 11,899,237, previously published as PCT/JP2019/043826, filed on Nov. 8, 2019.
Claims priority of application No. 2018-218153 (JP), filed on Nov. 21, 2018.
Prior Publication US 2024/0118486 A1, Apr. 11, 2024
Int. Cl. G02B 6/02 (2006.01); G02B 27/00 (2006.01); H04J 14/00 (2006.01)
CPC G02B 6/02042 (2013.01) [G02B 27/0012 (2013.01); H04J 14/052 (2023.08)] 9 Claims
OG exemplary drawing
 
1. A multicore optical fiber having only four cores having a radius a1 disposed in a longitudinal direction in square lattice shape, wherein the multicore optical fiber further comprises:
first cladding regions disposed around each of the cores and having a radius a2 with a refractive index lower than a refractive index of the cores, a specific relative refractive index difference to the cores αeing A1; and
a second cladding region disposed on an outer periphery of the first cladding regions and having a refractive index higher than the refractive index of the first cladding regions and lower than the refractive index of the cores, a specific relative refractive index difference to the core being Δ2,
wherein an outer diameter of the second cladding region is 125±1 μm,
bending loss at a wavelength of 1625 nm and a bending radius of 30 mm is 0.1 dB/100 turns or less, and
a cutoff wavelength is 1530 nm or less.