Multi-fiber light guide, device with a multi-fiber light guide and method for producing the same

Patent metadata

Field	Value
Publication number	US-12292594-B2
Application number	US-202217975979-A
Country	US
Kind code	B2
Filing date	Oct 28, 2022
Priority date	Apr 30, 2020
Publication date	May 6, 2025
Grant date	May 6, 2025

Abstract

A multi-fiber light guide includes: light guiding fibers, each fiber including an elongated glass core; a glass cladding, the cores being surrounded by the cladding to form a rigid and continuous glass element, the cores having a higher refractive index than the cladding such that light can be guided by a total reflection along the cores, which end in two abutting faces of the glass element such that light can be guided along the cores from one abutting face to the other abutting face; and an ion exchange layer at each of the abutting faces, the glass of the cores and the glass of the cladding including alkali ions, which are at least partly exchanged by alkali ions of a higher atomic number within the ion exchange layer at the abutting faces, the exchanged alkali ions within the ion exchange layer imparting a compressive stress at the abutting faces.

First claim

What is claimed is:

1. A multi-fiber light guide, comprising:
a plurality of light guiding fibers, each of the plurality of light guiding fibers including a glass core which is elongated, the plurality of light guiding fibers thereby including a plurality of the glass core which includes a glass;
a glass cladding which includes a glass, the plurality of the glass core being surrounded by the glass cladding such that the glass cladding with the plurality of the glass core form a glass element which is rigid and continuous, the plurality of the glass core having a higher refractive index than the glass cladding and thereby being configured such that a light can be guided by a total reflection along the plurality of the glass core, the glass element of the multi-fiber light guide including two abutting faces, with the plurality of the glass core ending in respective ones of the two abutting faces and thereby being configured such that the light can be guided along the plurality of the glass core from a respective one of the two abutting faces to another respective one of the two abutting faces, the glass element further including a glass shell which encompasses the glass cladding with the plurality of the glass core which are embedded, the glass shell extending between the two abutting faces; and
an ion exchange layer at each of the two abutting faces, the glass of the plurality of the glass core and the glass of the glass cladding including a plurality of alkali ions, which are at least partly exchanged by a plurality of alkali ions of a higher atomic number within the ion exchange layer at each of the two abutting faces, exchanged ones of the plurality of alkali ions within the ion exchange layer imparting a compressive stress at the two abutting faces, the ion-exchange layer also extending along the glass shell of the glass element.

2. The multi-fiber light guide according to claim 1 , wherein the multi-fiber light guide includes at least one of the following:
(a) a penetration depth of the ion-exchange layer in the plurality of the glass core is different from a penetration depth of the ion-exchange layer in the glass cladding;
(b) a coefficient of thermal expansion of the plurality of the glass core is different from the coefficient of thermal expansion of the glass cladding; and
(c) the glass shell includes a glass, the coefficient of thermal expansion of the glass of the glass shell being different from the coefficient of thermal expansion of the glass of the glass cladding.

3. The multi-fiber light guide according to claim 1 , wherein the glass element is a disc, a thickness of the disc being smaller than a shortest lateral dimension of the disc.

4. The multi-fiber light guide according to claim 1 , wherein the multi-fiber light guide has an elongated shape, and the length of the plurality of light guiding fibers is greater than a largest lateral dimension of the glass element.

5. The multi-fiber light guide according to claim 1 , wherein the multi-fiber light guide includes at least one of the following:
the two abutting faces differ in a surface area of respective ones of the two abutting surfaces;
the two abutting faces differ in a shape of respective ones of the two abutting surfaces; and
the glass element includes at least one bend.

6. The multi-fiber light guide according to claim 1 , wherein the multi-fiber light guide includes at least one of the following:
the plurality of the glass core are arranged in a plurality of hexagonal pattern;
the glass of the glass cladding is light absorbing;
the glass element of the multi-fiber light guide comprises a plurality of light absorbing fibers;
a center-to-center distance of adjacent ones of the plurality of light guiding fibers is from 2 μm to 500 μm.

7. The multi-fiber light guide according to claim 1 , wherein the multi-fiber light guide is configured for being a part of an assembly which includes a socket and the multi-fiber light guide sealed into the socket.

8. The multi-fiber light guide according to claim 7 , wherein the multi-fiber light guide is configured for being chemically toughened while sealed in the socket.

9. An optical sensor arrangement, comprising:
a housing including a multi-fiber light guide, the multi-fiber light guide including:
a plurality of light guiding fibers, each of the plurality of light guiding fibers including a glass core which is elongated, the plurality of light guiding fibers thereby including a plurality of the glass core which includes a glass;
a glass cladding which includes a glass, the plurality of the glass core being surrounded by the glass cladding such that the glass cladding with the plurality of the glass core form a glass element which is rigid and continuous, the plurality of the glass core having a higher refractive index than the glass cladding and thereby being configured such that a light can be guided by a total reflection along the plurality of the glass core, the glass element of the multi-fiber light guide including two abutting faces, with the plurality of the glass core ending in respective ones of the two abutting faces and thereby being configured such that the light can be guided along the plurality of the glass core from a respective one of the two abutting faces to another respective one of the two abutting faces, the glass element further including a glass shell which encompasses the glass cladding with the plurality of the glass core which are embedded, the glass shell extending between the two abutting faces; and
an ion exchange layer at each of the two abutting faces, the glass of the plurality of the glass core and the glass of the glass cladding including a plurality of alkali ions, which are at least partly exchanged by a plurality of alkali ions of a higher atomic number within the ion exchange layer at each of the two abutting faces, exchanged ones of the plurality of alkali ions within the ion exchange layer imparting a compressive stress at the two abutting faces, the ion-exchange layer also extending along the glass shell of the glass element;

a sensor element encased in the housing, the multi-fiber light guide configured for guiding a light from outside of the housing to the sensor element.

10. The optical sensor arrangement according to claim 9 , further comprising a light source within the housing, wherein the light source and the sensor element are positioned with respect to the multi-fiber light guide such that the light source is configured for emitting the light through the multi-fiber light guide and the sensor element is configured for receiving the light through the multi-fiber light guide.

11. The optical sensor arrangement according to claim 9 , wherein the optical sensor arrangement is an optical heart rate monitor.

12. The optical sensor arrangement according to claim 9 , wherein the optical sensor arrangement is a wearable device.

13. A method for producing a multi-fiber light guide, the method comprising the steps of:
providing a first preform with at least one rod of a first glass and at least one first glass element of a second glass having a lower refractive index than the first glass, the first preform being assembled such that the at least one rod is surrounded by the second glass;
heating the first preform and fusing the at least one rod to the at least one first glass element;
drawing the first preform to increase a length of the first preform and to reduce a lateral dimension of the at least one rod;
cutting the first preform, which has been drawn, into a first plurality of sections;
assembling the first plurality of sections to form a second preform;
cutting a second plurality of se

Assignees

• Schott Ag

Inventors

• Chai Wee Kiat
• Hettler Robert
• Weisshuhn Julia
• Steigleder Jan Philipp

Classifications

• C03C13/04

  Fibre optics, e.g. core and clad fibre compositions (light guides G02B6/00) · CPC title

• G01J1/0425

  using optical fibers · CPC title

• C03C25/602

  to perform ion-exchange between alkali ions (C03C25/605 takes precedence) · CPC title

• C03B2203/40

  Multifibres or fibre bundles, e.g. for making image fibres · CPC title

• C03B37/027

  Fibres composed of different sorts of glass, {e.g. glass optical fibres}(C03B37/0253, C03B37/028 take precedence) · CPC title