Effect of Volume Bragg Gratings Dispersion on Diffracted Beam Quality

Taidou, 周泰斗 Zhou; Xiaobao, 梁小宝 Liang; Lei, 赵磊 Zhao; Lin, 王 琳 Wang; Chao, 李超 Li; Yun, 罗韵 Luo; Jianjun, 王建军 Wang; Feng, 景峰 Jing

doi:10.3788/cjl201744.0201019

Cited by 2 publications

(3 citation statements)

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“…Besides the diffraction efficiency, the beam quality is also an important indicator in evaluating the combining effect. Considering the parameters of the input beam and VBGs, the deterioration of the beam quality factor ( M 2 ) after VBG diffraction can be expressed as 21 :

{M}_{\text{diff}}^{2}={M}_{\text{1}}^{2}\sqrt{1+\frac{1}{(4{\Lambda }^{2}-{\lambda }_{0}^{2})\mathrm{ln}2}{\left(\frac{\unicode{x02206}\lambda ^{\prime} }{\unicode{x02206}{\theta }_{0}^{^{\prime} }}\right)}^{2}},

where

{M}_{1}^{2}

is the initial beam quality factor of the incident beam,

\unicode{x02206}\lambda ^{\prime}

is the full‐width half‐maximum (FWHM) of the spectrum,

\unicode{x02206}{\theta }_{0}^{^{\prime} }

is the DA of the incident beam,

{\Lambda }

is the spatial period.…”

Section: Design and Analysis Of Sbcmentioning

confidence: 99%

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Comparison of spectral beam combining based on reflecting volume Bragg grating, with and without collimating lenses

Wang

Zhan

Xiang

et al. 2022

Micro & Optical Tech Letters

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On the basis of the principle of spectral beam combining (SBC), a simple combining system using a reflecting volume Bragg grating as a combiner was designed in which two focusing lenses were used to control the incident angles of input beams, and two concave lenses were used to solve the problem of beam divergence caused by focusing lenses. The effects of the beam divergence angle (DA) on diffraction efficiency and beam quality were analyzed theoretically. The simulation results showed that a larger DA will reduce diffraction efficiency and lead to deterioration of beam quality. In the SBC experiment, the performances of the output beam with and without concave lenses were compared. The experimental results showed that, when the concave lenses were not inserted, the measured output power was 503 mW with a combining efficiency of 85.3% and the beam quality factor of 1.68. The experiment further showed that the combined power was 566 mW with a combining efficiency of 96% and a beam quality factor of 1.31 when concave lenses were used.

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{M}_{\text{diff}}^{2}={M}_{\text{1}}^{2}\sqrt{1+\frac{1}{(4{\Lambda }^{2}-{\lambda }_{0}^{2})\mathrm{ln}2}{\left(\frac{\unicode{x02206}\lambda ^{\prime} }{\unicode{x02206}{\theta }_{0}^{^{\prime} }}\right)}^{2}},

where

{M}_{1}^{2}

is the initial beam quality factor of the incident beam,

\unicode{x02206}\lambda ^{\prime}

is the full‐width half‐maximum (FWHM) of the spectrum,

\unicode{x02206}{\theta }_{0}^{^{\prime} }

is the DA of the incident beam,

{\Lambda }

is the spatial period.…”

Section: Design and Analysis Of Sbcmentioning

confidence: 99%

“…Besides the diffraction efficiency, the beam quality is also an important indicator in evaluating the combining effect. Considering the parameters of the input beam and VBGs, the deterioration of the beam quality factor (M 2 ) after VBG diffraction can be expressed as 21 :…”

Section: Analysis Of the Performancementioning

confidence: 99%

Comparison of spectral beam combining based on reflecting volume Bragg grating, with and without collimating lenses

Wang

Zhan

Xiang

et al. 2022

Micro & Optical Tech Letters

View full text Add to dashboard Cite

show abstract

“…The beam quality factor is one of the key technical indexes to evaluate the beam quality in the SBC system. However, it can be influenced by many factors, such as the spectral line width, the disturbance of the laser array, and the dispersion characteristics of the grating [9][10][11][12]. As the powers of the laser array are increased, the grating thermal deformation, which induces degeneration of the combined beam quality, becomes more significant [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Dynamic of Grating Thermal Deformation on Beam Quality for Spectral Beam Combining

Deng

Zhan

et al. 2022

Front. Phys.

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For spectral beam combining, an experimental system of dynamic beam quality caused by the thermal deformation of a grating has been designed and established. According to the theoretical model established, the distribution of the temperature field, as well as the thermal deformation of the grating, has been analyzed. Further, the combined beam quality and the intensity distribution have been numerically calculated in detail. The results show that the maximum temperature and the grating thermal deformation increase with the extension of irradiation time, resulting in side lobes appearing in the intensity distribution. In the experiment, the measured combined beam quality factor Mx2 was 1.29 without the thermal deformation. When the grating was heated by pump lasers at different times, Mx2 can arrive at 1.34, 1.37, and 1.41, respectively. The results reveal that the combined beam quality increases with the increase in irradiation time and changes rapidly at the beginning of heating, consistent with the theoretical analysis. The discussion and analysis of the dynamic beam quality are potentially valuable for reducing the influence of thermal deformation on the beam quality.

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Effect of Volume Bragg Gratings Dispersion on Diffracted Beam Quality

Cited by 2 publications

References 0 publications

Comparison of spectral beam combining based on reflecting volume Bragg grating, with and without collimating lenses

Comparison of spectral beam combining based on reflecting volume Bragg grating, with and without collimating lenses

Dynamic of Grating Thermal Deformation on Beam Quality for Spectral Beam Combining

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