PHOTONIC BANDGAP FIBERS

• US 20090122308A1
• Filed: 08/07/2008
• Published: 05/14/2009
• Est. Priority Date: 12/30/2004
• Status: Active Grant

• Current Assignee: Liang Dong, Xiang Peng
• Original Assignee: Liang Dong, Xiang Peng
• Inventors: Dong, Liang, Peng, Xiang
• Granted Patent: US 7,792,394 B2
• Time in Patent Office: Days
• US Class Current: 356/301
• CPC Class Codes: C03B 2203/04 Polygonal outer cross-section, e.g. triangular, square
• CPC Class Codes: C03B 2203/12 Non-circular or non-elliptical cross-section, e.g. planar core
• CPC Class Codes: C03B 2203/14 Non-solid, i.e. hollow products, e.g. hollow clad or with core-clad interface
• CPC Class Codes: C03B 2203/16 Hollow core
• CPC Class Codes: C03B 2203/42 Photonic crystal fibres, e.g. fibres using the photonic bandgap PBG effect, microstructured or holey optical fibres
• CPC Class Codes: C03B 37/01205 starting from tubes, rods, fibres or filaments C03B37/014 takes precedence
• CPC Class Codes: C03B 37/01208 for making preforms of microstructured, photonic crystal or holey optical fibres
• CPC Class Codes: C03B 37/0122 for making preforms of photonic crystal, microstructured or holey optical fibres
• CPC Class Codes: G01N 2021/655 Stimulated Raman
• CPC Class Codes: G01N 21/65 Raman scattering
• CPC Class Codes: G01N 21/774 the reagent being on a grating or periodic structure
• CPC Class Codes: G02B 6/02238 Low dispersion slope fibres
• CPC Class Codes: G02B 6/023 having different index layers arranged around the core for guiding light by reflection, i.e. 1D crystal, e.g. omniguide
• CPC Class Codes: G02B 6/02304 Core having lower refractive index than cladding, e.g. air filled, hollow core
• CPC Class Codes: G02B 6/02328 Hollow or gas filled core
• CPC Class Codes: 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
• 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: G02B 6/4206 Optical features G02B6/4207, G02B6/421 take precedence

Abstract

Included among the many structures described herein are photonic bandgap fibers designed to provide a desired dispersion spectrum. Additionally, designs for achieving wide transmission bands and lower transmission loss are also discussed. For example, in some fiber designs, smaller dimensions of high index material in the cladding and large core size provide small flat dispersion over a wide spectral range. In other examples, the thickness of the high index ring-shaped region closest to the core has sufficiently large dimensions to provide negative dispersion or zero dispersion at a desired wavelength. Additionally, low index cladding features distributed along concentric rings or circles may be used for achieving wide bandgaps.

Claims

1. An gas analyzer comprising:

a light source;

an optical fiber optically coupled to said light source, said optical fiber comprising a core and a cladding, said optical fiber further comprising one or more holes in said core or in proximity to said core for receiving said gas; and

at least one optical detector disposed to receive light from said core of said fiber that is affected by said gas.

2. The gas analyzer of claim 1, wherein said optical fiber comprises a photonic bandgap fiber.

3. The gas analyzer of claim 2, wherein said core has a width larger than about 20 μ

m.

4. The gas analyzer of claim 1, wherein said optical fiber further comprises openings in sides thereof to allow gas flow in and out of said holes in said fiber.

5. The gas analyzer of claim 1, further comprising at least one optical and gas multiplexer configured to combine the optical beam and the gas.

6. The gas analyzer of claim 5, further comprising at least one optical and gas demultiplexer configured to separate the optical beam and the gas.

7. The gas analyzer of claim 6, further comprising a reflective narrow band filter disposed so as to separate pump and Raman-scattered signal light.

8. The gas analyzer of claim 6, wherein said detector is arranged to measure spectral transmission of the gas to identify or quantify the gas, or both.

9. The gas analyzer of claim 6, wherein said detector is arranged to measure a Raman-scattered signal to identify or quantify the gas, or both.

10. The gas analyzer of claim 9, wherein said detector is arranged to measure a backward-propagating Raman-scattered signal.

11. The gas analyzer of claim 9, wherein said detector is arranged to measure a forward-propagating Raman-scattered signal.