Microstructured fiber and supercontinuum light source

• US 10,698,155 B2
• Filed: 04/29/2019
• Issued: 06/30/2020
• Est. Priority Date: 03/25/2014
• Status: Active Grant

• Current Assignee: NKT Photonics A/S (NKT A/S)
• Original Assignee: NKT Photonics A/S (NKT A/S)
• Inventors: Lyngsoe, Jens Kristian, Jacobsen, Christian
• Primary Examiner(s): Kim, Ellen E
• Application Number:
  US16/396,802
• Publication Number:
  US 20190324197A1
• Time in Patent Office: 428 Days
• CPC Class Codes: G02B 21/0004 specially adapted for specific applications
• CPC Class Codes: G02B 21/0012 Surgical microscopes counterbalanced structures for surgical microscopes G02B7/001
• CPC Class Codes: G02B 21/0032 Optical details of illumination, e.g. light-sources, pinholes, beam splitters, slits, fibers G02B21/0036 - G02B21/008; means for illumination of specimens in general G02B21/06
• CPC Class Codes: G02B 21/06 Means for illuminating specimens
• CPC Class Codes: G02B 21/16 adapted for ultraviolet illumination ; Fluorescence microscopes G02B21/0076 takes precedence
• CPC Class Codes: G02B 6/02214 tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
• CPC Class Codes: G02B 6/02347 Longitudinal structures arranged to form a regular periodic lattice, e.g. triangular, square, honeycomb unit cell repeated throughout cladding
• CPC Class Codes: G02B 6/02357 Property of longitudinal structures or background material varies radially and/or azimuthally in the cladding, e.g. size, spacing, periodicity, shape, refractive index, graded index, quasiperiodic, quasicrystals
• CPC Class Codes: G02B 6/02361 Longitudinal structures forming multiple layers around the core, e.g. arranged in multiple rings with each ring having longitudinal elements at substantially the same radial distance from the core, having rotational symmetry about the fibre axis
• CPC Class Codes: G02F 1/3528 for producing a supercontinuum

Abstract

A microstructured optical fiber including a core region and a cladding region which surrounds the core region. The cladding region includes a plurality of cladding features within a cladding background material, wherein the cladding region includes an inner cladding region with at least one inner ring of cladding features and an outer cladding region with at least three outer cladding rings of outer cladding features. The inner cladding features have a first characteristic diameter and the outer cladding region includes a plurality of outer cladding features having a characteristic diameter smaller than the first characteristic diameter. The first characteristic diameter is at least about 10% larger than an average diameter of the outer cladding features and the core region has a diameter of at least about 2 μm. A cascade optical fiber with at least one fiber as described, as well as a source of optical supercontinuum generation.

Claims

1. A microstructured optical fiber having a length and a longitudinal axis along its length and comprising:

a core region capable of guiding light along said longitudinal axis and a cladding region which surrounds the core region,

said cladding region comprising a cladding background material and a plurality of cladding features within the cladding background material, said cladding features being arranged around the core region,

wherein the core region has a refractive index which is less than or equal to a refractive index of the cladding background material,

wherein said cladding region comprises an inner cladding region comprising an inner cladding ring of inner cladding features having a first characteristic diameter d₁ and an outer cladding region comprising an outer cladding ring of outer cladding features,

said plurality of cladding features comprising said inner cladding features of said inner ring and said outer cladding features of said outer cladding ring,

wherein said inner cladding ring and said outer cladding ring each comprise bridges of cladding background material separating adjacent features of the ring,

wherein the bridges of the inner ring have an average minimum width w₁, and the bridges of said outer cladding ring have an average minimum width w₂, where w₂ is at least about 10% larger than w₁,

wherein the outer cladding features have a characteristic diameter smaller than the first characteristic diameter d₁,

wherein the average minimum width w₁ is smaller than the first characteristic diameter d₁, and

wherein the core region has a diameter of at least about 2 μ

m.

2. The microstructured optical fiber of claim 1, wherein said core region has a diameter larger than about 10 μ

m.

3. The microstructured optical fiber of claim 1, wherein said core region has a substantially identical diameter along substantially the entire length of the fiber.

4. The microstructured optical fiber of claim 1, wherein w₁ is about 1.2 μ

m or less.

5. The microstructured optical fiber of claim 1, wherein the core region comprises a core background material which is doped with dopant material decreasing the refractive index of the core region compared to the core background material in undoped condition.

6. A microstructured optical fiber having a length and a longitudinal axis along its length and comprising:

a core region capable of guiding light along said longitudinal axis and a cladding region which surrounds the core region,

said cladding region comprising a cladding background material and a plurality of cladding features within the cladding background material, said cladding features being arranged around the core region,

wherein the core region has a refractive index which is less than or equal to a refractive index of the cladding background material,

wherein said cladding region comprises an inner cladding region comprising an innermost ring of cladding features having a first characteristic diameter d₁ and an outer cladding region comprising an outer cladding ring of outer cladding features,

said plurality of cladding features comprises said cladding features of said innermost ring and of said outer cladding ring,

wherein said innermost ring and said outer cladding ring each comprise bridges of cladding background material separating adjacent features of the ring, wherein the bridges of the innermost ring have an average minimum width w₁, where an average minimum width (w₂) of the bridges of an outer ring is at least about 10% larger than the average minimum width (w₁) of the bridges of the innermost ring,

wherein the outer cladding features have a characteristic diameter smaller than the first characteristic diameter (d₁), and

wherein w₁ is smaller than the first characteristic diameter (d₁).

7. The microstructured optical fiber of claim 6, wherein said core region has a diameter of at least about 2 μ

m.

8. The microstructured optical fiber of claim 6, wherein said core region has a diameter larger than about 10 μ

m.

9. The microstructured optical fiber of claim 6, wherein w₁ is about 1.2 μ

m or less.

10. The microstructured optical fiber of claim 6, wherein the core region comprises a core background material which is doped with dopant material decreasing the refractive index of the core region compared to the core background material in undoped condition.

11. The microstructured optical fiber of claim 6, wherein said core region has a substantially identical diameter along substantially the entire length of the fiber.

12. A microstructured optical fiber having a length and a longitudinal axis along its length and comprising:

a core region capable of guiding light along said longitudinal axis and a cladding region which surrounds the core region,

said cladding region comprising a cladding background material and a plurality of cladding features within the cladding background material, said cladding features being arranged around the core region,

wherein the core region has a refractive index which is less than or equal to a refractive index of the cladding background material,

wherein said cladding region comprises an inner cladding region comprising an innermost ring of cladding features having a first characteristic diameter d₁ and an outer cladding region comprising an outer cladding ring of outer cladding features,

wherein said innermost ring and said outer cladding ring each comprise bridges of cladding background material separating adjacent features of the ring, wherein the bridges of the innermost ring have an average minimum width w₁, where an average minimum width w₂ of the bridges of said outer ring are at least about 10% larger than w₁, and

said microstructured optical fiber being configured to provide supercontinuum radiation including light at wavelengths below 500 nm when pumped by pump radiation generated by a pump laser source.

13. The microstructured optical fiber of claim 12, wherein the outer cladding features have a characteristic diameter smaller than the first characteristic diameter d₁.

14. The microstructured optical fiber of claim 12, wherein w₁ is smaller than the first characteristic diameter d₁.

15. The microstructured optical fiber of claim 12, wherein the core region has a diameter of at least about 2 μ

m.

16. The microstructured optical fiber of claim 12, wherein said core region has a diameter larger than about 10 μ

m.

17. The microstructured optical fiber of claim 12, wherein w₁ is about 1.2 μ

m or less.

18. The microstructured optical fiber of claim 12, wherein the core region comprises a core background material which is doped with dopant material decreasing the refractive index of the core region compared to the core background material in undoped condition.

19. The microstructured optical fiber of claim 12, wherein said core region has a substantially identical diameter along substantially the entire length of the fiber.

20. The microstructured optical fiber of claim 12, wherein the pump radiation comprises a pump wavelength which is between about 1000 nm and about 1100 nm and is up to about 200 nm above or below the zero dispersion wavelength of the microstructured optical fiber.