Multiplexed volume Bragg gratings for spectral beam combining of high power fiber lasers

Divliansky, Ivan; Ott, Daniel; Anderson, Brian; Drachenberg, Derrek R.; Rotar, Vasile; Venus, George; Glebov, Leonid

doi:10.1117/12.909519

Cited by 6 publications

(8 citation statements)

References 9 publications

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“…For example, losses due to lower than 99% diffraction efficiency of the gratings lead to losses in both the combining and the splitting processes in a given resonator round trip. Five-beam combining setup using a single multiplexed VBG as combining element [19].…”

Section: Spectral and Coherent Laser Beam Combining By Volume Bragg Gmentioning

confidence: 99%

Volume Bragg Gratings: Fundamentals and Applications in Laser Beam Combining and Beam Phase Transformations

Divliansky¹

2017

Holographic Materials and Optical Systems

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Two major volume Bragg grating (VBG) applications will be presented and in particular laser beam combining and holographically encoded phase masks. Laser beam combining is an approach where multiple lasers are combined to produce more power. Spectral beam combining is a technique in which different wavelengths are superimposed spatially (combined) using a dispersive element such as a volume Bragg grating. To reduce the complexity of such combining system instead of multiple individual VBGs, it will be demonstrated that a single holographic element with multiple VBGs recorded inside could be used for the same purpose. Similar multiplex volume holographic elements could be used for coher ent beam combining. In this case, the gratings operate at the same wavelength and have degenerate output. Such coherent combining using gratings written in photothermorefractive (PTR) glass will be discussed. The chapter also demonstrates that binary phase profiles may be encoded into volume Bragg gratings, and that for any probe beam capable of satisfying the Bragg condition of the hologram, this phase profile will be present in the diffracted beam. A multiplexed set of these holographic phase masks (HPMs) can simultaneously combine beams while also performing mode conversion. An approach for making HPMs fully achromatic by combining them with a pair of surface gratings will be outlined.Keywords: holography, volume Bragg gratings, beam combining, phase plates, photothermo refractive glass, multiplexed volume gratings © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Volume Bragg gratings Description and propertiesVolume grating as its name suggest is a grating that occupies the volume of a medium. Typically, for such gratings the term volume Bragg gratings (VBGs) is used in relation to Sir William Bragg who in 1915 used diffraction of light propagating through a crystal to determine the crystal's lattice structure [1]. What he found was that at certain conditions the light is strongly diffracted by the crystal. Such condition is called "resonant condition" or also "Bragg condition." Here is also the place to make the distinction between surface and volume Bragg gratings. If we start with a surface grating and start increasing its thickness at some point the different diffraction orders will reduce to a moment where there will be only one order. This defines the transition to a volume grating behavior [2].There are two basic types of VBGs which is shown in Figure 1. The first one is a transmission Bragg grating (TBG) for which if the incident light satisfies the Bragg condition it is not transmitted but also diffracted. The second type is a reflection Bragg grating (RBG) which behaves like a mirror for incoming light that matches the Bragg condition.For simplicity, in Figure 1, fo...

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Section: Spectral and Coherent Laser Beam Combining By Volume Bragg Gmentioning

confidence: 99%

Volume Bragg Gratings: Fundamentals and Applications in Laser Beam Combining and Beam Phase Transformations

Divliansky¹

2017

Holographic Materials and Optical Systems

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“…For examples, in reference [4] BraggsGate TM combiner is manufactured by optigate corporation for high efficiency and high power. In this case, centre wavelength 930-980 nm and 1030-1100 nm is taken, however in reference [5] authors deal with Braggs grating for spectral beam combination using diffraction effect. In this case, they consider two wavelengths of 1063.5 nm and 1064.0 nm.…”

Section: Introductionmentioning

confidence: 99%

“…Basically, beam combination plays an important role for high efficiency and good beam quality of power and radiance (brightness) in laser technology [2,3]. To improve such quality and power by the method of beam combination, recently different structures are used for the same using various technique [4,5]. For examples, in reference [4] BraggsGate TM combiner is manufactured by optigate corporation for high efficiency and high power.…”

Section: Introductionmentioning

confidence: 99%

Analysis and simulation of silicon grating structure for spectral beam combining application

Palai¹

2015

Optik

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“…However, further scaling to higher power levels is fundamentally limited due to the onset of thermal and nonlinear effects in the fiber. Spectral beam combining (SBC) and coherent beam combining (CBC) are the two major complementary methods of beam combining in the effort to reach multi-kilowatt diffraction limited beams [1][2][3]. Simultaneously with the progress of the beam combining techniques, a lot of effort has been put into designing and developing LMA fibers that support only one or few higherorder modes with the purpose of increasing the nonlinear effects threshold by increasing the effective fiber mode area.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous laser beam combining and mode conversion using multiplexed volume phase elements

et al. 2014

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To scale to power levels of up to tens of kW with a few fiber lasers, the best candidates are large core fibers guiding a few large-area higher order modes with the outputs of these fibers combined into a single beam. However, in many applications it is desirable to convert these higher order modes into a Gaussian profile. Here, we propose a method to accomplish this task via single volume phase element. This element accepts multiple higher order mode beams and simultaneously converts and combines them to a single Gaussian profile in the far field.

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Multiplexed volume Bragg gratings for spectral beam combining of high power fiber lasers

Cited by 6 publications

References 9 publications

Volume Bragg Gratings: Fundamentals and Applications in Laser Beam Combining and Beam Phase Transformations

Volume Bragg Gratings: Fundamentals and Applications in Laser Beam Combining and Beam Phase Transformations

Analysis and simulation of silicon grating structure for spectral beam combining application

Simultaneous laser beam combining and mode conversion using multiplexed volume phase elements

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