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Method for writing double holographic grating at one time by single pulsed laser

A holographic grating, ultra-short pulse laser technology, applied in the field of holographic grating

Inactive Publication Date: 2003-10-15
SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the above two methods have a common disadvantage, that is, the coherence generated by the beam splitting and focusing of a single output pulse can only form one micro-grating at a time.

Method used

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  • Method for writing double holographic grating at one time by single pulsed laser
  • Method for writing double holographic grating at one time by single pulsed laser
  • Method for writing double holographic grating at one time by single pulsed laser

Examples

Experimental program
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Effect test

Embodiment 1

[0026] The selected pulse width is 50fs (5×10 -14 second) femtosecond pulse, the wavelength is 800nm, the pulse repetition rate is 1Hz, and the pulse energy is 70μJ. The beam is divided into two beams by the beam splitter, and the beam diameter is 6mm. The coherence of the two beams is achieved by frequency doubling crystal (BBO) generated second harmonic to achieve. The angle between the two beams of light is 45°, and the sample is controlled by a three-dimensional mobile platform operated by a computer. Use two focusing lenses with a focal length of 10cm to focus the two light beams at a distance of about 35 μm from the surface of the quartz glass, and the diameter of the spot at the focus is about 30 μm, so that a double holographic grating is formed on the surface of the quartz glass, and observed with an optical microscope (100 × objective lens) The result is as image 3 As shown, the structural period is 1 μm.

Embodiment 2

[0028] Similar to the way of embodiment 1, the selected pulse width is 120fs (1.2 × 10 -13 second) ultrashort pulse, the wavelength is 800nm, the pulse repetition rate is 5Hz, the pulse energy is 80μJ, the beam diameter is 6mm, and the angle between the two beams is 45°. The beams are focused and intersect at the focal point, and the intersection point is about 30 μm away from the surface of the lead glass. The spot diameters of the two beams at the focal point are 35 and 30 μm respectively, thus forming a double holographic grating on the surface of the lead glass, using an optical microscope (100 × objective lens) The observed results are as Figure 4 As shown, the structural period is 1 μm.

Embodiment 3

[0030] As in Example 1, the selected pulse width is 500fs (5 × 10 -13 second) ultrashort pulse, the wavelength is 800nm, the pulse repetition rate is 10Hz, the pulse energy is 90μJ, the angle between the two beams is 60°, and the two beams are focused by two focusing lenses with focal lengths of 20cm and 10cm The distance between the intersection point and the K9 glass surface is about 40 μm, and the spot diameters of the two beams at the focal point are 50 μm and 30 μm respectively, so that a double holographic grating is formed on the K9 glass surface, and the size of the two holographic gratings is obviously different. objective lens) observed results such as Figure 5 As shown, the structural period is 0.8 μm.

[0031] In summary, the present invention utilizes the ultrashort pulse laser with a single pulse width less than 1 ps to achieve coherent superposition in space and time after beam splitting, and can write double holographic micro-gratings in a solid transparent m...

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Abstract

The once double holographic micro grating writing process includes the following steps: adopting supershort pulse laser with pulse width smaller than 1 ps; splitting in a splitter into two beams focused separately by two convexes and crossed at or near the focus to realize temporal and spatial coherent; adopting transparent solid medium; controlling the energy of single pulse output by the laser to make each of the split pulse possess energy density smaller than that energy density threshold to ablate the transparent medium and the energy density reached in constructive interference just greater than the threshold; converging the two coherent supershort laser beams onto the surface of the transparent medium to produce two periodical microstructures and to form double holographic micro grating simultaneously.

Description

technical field [0001] The invention relates to a holographic grating, in particular to a method for writing a double holographic grating at one time with a single pulse laser, specifically, a method for using a pulse width less than 1 ps (10 -12 second) ultrashort pulse laser interference, a method of writing double holographic gratings on the surface of solid transparent media at one time. Background technique [0002] Generally, holographic gratings are made of long pulse or even continuous laser coherence-induced photosensitive materials. Pulse width less than 1ps (10 -12 second) ultra-short pulse laser, which has a very high peak light intensity due to its short pulse width, not only can be used for the preparation of holographic gratings of photosensitive materials (such as photorefractive crystals, photopolymer materials), but also can be used for non-photosensitive Fabrication of gratings from materials such as films and various transparent glass materials. Curren...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02B5/18G02B5/32G03H1/04
Inventor 曲士良赵崇军邱建荣朱从善
Owner SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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