Sidelobe suppression for coherent beam combining with laser beams placed along a Fermat spiral

Yang Gao; Jiali Liao; Jun Xu; Zhanrong Zhou

doi:10.3788/COL202220.021405

Journals >Chinese Optics Letters >Volume 20 >Issue 2 >Page 021405 > Article

Chinese Optics Letters
Vol. 20, Issue 2, 021405 (2022)

Sidelobe suppression for coherent beam combining with laser beams placed along a Fermat spiral

Yang Gao^1、*, Jiali Liao^2、3, Jun Xu¹, and Zhanrong Zhou^1、**

Author Affiliations

¹Xi’an Research Institute of High Technology, Xi’an 710025, China

²School of Physics and Optoelectronic Engineering, Xidian University, Xi’an 710071, China

³State Key Laboratory of Pulsed Power Laser Technology, Hefei 230037, China

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DOI: 10.3788/COL202220.021405 Cite this Article Set citation alerts

Yang Gao, Jiali Liao, Jun Xu, Zhanrong Zhou. Sidelobe suppression for coherent beam combining with laser beams placed along a Fermat spiral[J]. Chinese Optics Letters, 2022, 20(2): 021405 Copy Citation Text

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Abstract

We proposed an aperiodic laser beam distribution, in which the laser beams are placed along a Fermat spiral, to suppress the sidelobe power in the coherent beam combining. Owing to the changed distances between two consecutive beams, the conditions of the sidelobe suppression are naturally satisfied. The Fermat spiral array was demonstrated to achieve a better sidelobe suppression than the periodic arrays, and the effects of various factors on the sidelobe suppression were analyzed numerically. Experiments were carried out to verify the sidelobe suppression by different Fermat spiral arrays, and the results matched well with the simulations.

Keywords

coherent beam combining Fermat spiral intensity distribution sidelobe suppression

r_{i} = s \sqrt{\frac{i}{π}}, n = 1, 2, 3, \dots,

(1)

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θ_{i} = 2 π β i, n = 1, 2, 3, \dots,

(2)

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U = \sum_{i = 1}^{n} A_{i} (\overset{⇀}{r}) \times {circ}_{i} (\overset{⇀}{r}),

(3)

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A_{i} (\overset{⇀}{r}) = A_{0} \exp (- \frac{{| \overset{⇀}{r} - \overset{⇀}{r_{i}} |}^{2}}{w_{0}^{2}}),

(4)

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{circ}_{i} (\overset{⇀}{r}) = {\begin{matrix} \begin{matrix} 1, & {| \overset{⇀}{r} - \overset{⇀}{r_{i}} |}^{2} \leq a^{2} / 4 \end{matrix} \\ \begin{matrix} 0, & {| \overset{⇀}{r} - \overset{⇀}{r_{i}} |}^{2} > a^{2} / 4 \end{matrix} \end{matrix},

(5)

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U (f_{x}, f_{y}) = \frac{e^{j k z}}{j λ z} \exp [\frac{j k}{2 z} (x^{2} + y^{2})] F {U (x, y)}_{f_{x} = \frac{x}{λ z}, f_{y} = \frac{y}{λ z}},

(6)

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{\begin{matrix} I_{0} = I_{main} / I_{total} \\ η = I_{main - \max} / I_{side - \max} \end{matrix},

(7)

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Yang Gao, Jiali Liao, Jun Xu, Zhanrong Zhou. Sidelobe suppression for coherent beam combining with laser beams placed along a Fermat spiral[J]. Chinese Optics Letters, 2022, 20(2): 021405

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