Method for writing high power resistant Bragg gratings using short wavelength ultrafast pulses

A Bragg grating, ultrafast light technology, used in diffraction gratings, light guides, optics, etc., to solve problems such as higher-order gratings not always enough

Inactive Publication Date: 2012-07-11
UNIV LAVAL
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, for high power applications, the intensity of the higher order grating at the wavelength of interest may not always be sufficient

Method used

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  • Method for writing high power resistant Bragg gratings using short wavelength ultrafast pulses
  • Method for writing high power resistant Bragg gratings using short wavelength ultrafast pulses
  • Method for writing high power resistant Bragg gratings using short wavelength ultrafast pulses

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Embodiment

[0051] In one example of the embodiment of the present invention, use and figure 1 A similar system shown writes Bragg gratings in optical fibers. The waveguide used in this experiment is a double-clad ytterbium-doped silica fiber. The pump core of the double-clad fiber has a diameter of 128 μm and an octagonal geometry, while a single core has a diameter of 6 μm, and is co-doped with 2 mol% of Al alone. 2 O 3 , So no photosensitive elements such as germanium are added to the fiber glass composition.

[0052] A Ti-sapphire regenerative amplifier system (Coherent Legend-HE, trademark) is used as a pump source. The Ti-sapphire regenerative amplifier system generates 3.5 mJ / pulse femtosecond laser pulses with a repetition rate of 1 kHz and a center wavelength of λ=806 nm. The duration of the Fourier transform finite pulse is measured to be about 35 fs. A BBO crystal (Eksma Optics, BBO-1502, trademark) was used to generate the second harmonic of 403nm with a maximum of 1.0mJ. A dic...

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Abstract

A method for writing a Bragg grating in a rare-earth doped glass optical waveguide is provided. Ultrafast optical pulses are generated, preferably in the femtosecond range and having a writing wavelength in the range of 300nm to 700nm and an intensity sufficient to induce a change of refractive index in the rare-earth doped glass waveguide through densification. The optical pulses are diffracted using a phase mask, to generate an interference pattern having a pitch providing a fundamental Bragg resonance corresponding to the target wavelength to be reflected by the grating. The interference pattern is impinged on a region of the rare-earth doped glass waveguide, which is heated to a temperature above a threshold of about 350 DEG C, for a predetermined heating period. Advantageously, the heating step allows the elimination of photodarkening effects which would otherwise be present in the waveguiding properties of the waveguide.

Description

Technical field [0001] The present invention relates to the field of Bragg grating manufacturing, and more specifically to a method of writing Bragg gratings in rare earth doped glass waveguides for high-power applications using short-wavelength ultrafast pulses. Background technique [0002] High-power applications, such as high-power fiber lasers, require high-intensity strong Bragg gratings that can withstand the light circulating in the fiber. Using the physical method of UV-induced defect resonance (this method is generally used for writing fiber Bragg gratings (FBG) in silica fibers), the gratings obtained are limited to photosensitive fibers, and usually cannot be inscribed on rare earth doped laser gain media. Miscellaneous fiber. This in turn means that the fiber laser cavity will need to activate the fusion splice between the fiber and the photosensitive fiber. These joints may cause extra cavity loss and are not suitable for certain activated fiber geometries, especi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02B6/124G02B5/18
CPCG02B5/1857G02B6/02142
Inventor 雷亚尔·瓦利马丁·贝尼耶
Owner UNIV LAVAL
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