# US 12,105,321 B2 · Multi-core fiber and manufacturing method thereof and multi-core fiber marker

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- Number: US 12,105,321 B2
- Document ID: US12105321B2
- Status: Granted
- Kind: B2
- Application number: 17/698,796
- Filed: 2022-03-18
- Published: 2023-06-29
- Granted: 2024-10-01
- Earliest claimed: 2021-12-28
- Assignees: Sterlite Technologies Limited
- Applicants: Sterlite Technologies Limited
- Inventors: Anand Pandey; Ranjith Balakrishnan
- Web page: https://patentgrep.com/patent/US12105321B2

## CPC

- G02B 6/02042: {Multicore optical fibres}
- G02B 6/02338: {Structured core, e.g. core contains more than one material, non-constant refractive index distribution in core, asymmetric or non-circular elements in core unit, multiple cores, insertions between core and clad}
- G02B 6/4482: {Code or colour marking}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

The present disclosure provides a multi-core fiber (MCF) and manufacturing method thereof and an MCF marker (or marker). The MCF (100) comprises a plurality of cores (102) and a marker (108). Each core is associated with a core diameter (104) and a core-placement-radius (106) and the marker (108) is associated with a marker diameter (110) and a marker-placement-radius (112). The marker has a marker core (116) and a marker clad (118) with a D/d ratio between 5 to 20. During manufacturing, the MCF is drawn from a preform assembly (200) having a top hollow handle (202) with a handle thickness (114) attached on a top end of a glass preform (204) that has a plurality of core holes (206) and a marker hole (210), wherein the marker hole (210) is at least partially covered by the top hollow handle of the handle thickness (114).

## Claims

### Claim 1

A multi-core fiber (MCF) (100) comprising:
a plurality of cores (102), wherein each core is associated with a core diameter (104) and a core-placement-radius (106); and
a marker (108), wherein the marker (108) is associated with a marker diameter (110) and a marker-placement-radius (112), wherein the marker diameter (110) is equal to a core diameter (104), wherein the marker-placement-radius (112) is different from the core-placement-radius (106), wherein the marker (108) has a marker core (116) and a marker clad (118), wherein a first ratio of the clad diameter to core diameter of the marker (108) is greater than a second ratio of clad diameter to core diameter of the plurality of cores (102).

### Claim 2 (depends on 1)

The multi-core fiber (100) as claimed in claim 1, wherein the first ratio of the marker clad (118) to the marker core (116) is in a range of 5 to 20.

### Claim 3 (depends on 1)

The multi-core fiber (100) as claimed in claim 1, wherein the marker (108) is doped with at least one of an up-dopant, a down-dopant, and a colour dopant.

### Claim 4 (depends on 1)

The multi-core fiber (100) as claimed in claim 1, wherein the marker (108) is used to transmit light signals.

### Claim 5 (depends on 1)

The multi-core fiber (100) as claimed in claim 1, wherein the marker clad (118) and outer clad (120) are made of same material.