Nonlinear optical refractive index measurements of pure water via Z-scan technique at 800 nm
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866929698773139456 |
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| author | Betka, Ilyes |
| author_facet | Betka, Ilyes |
| contents | The determination of the nonlinear optical coefficient \( n_2 \) of pure water is of great interest for applications such as imaging biological systems, performing femtosecond laser surgery, and underwater ablation. Traditionally, probing third-order nonlinearity while eliminating the thermo-optic effect requires high pulse energy and low repetition rate laser sources. In this article, a low-cost, simple, and versatile third-order nonlinear characterization technique for the Z-scan closed-aperture mode has been developed to determine the nonlinear refractive index of pure water at 800 nm, with a pump duration of 140 fs and a repetition rate of 80 MHz. Experimental results reveal an \( n_2 \) value of \( (8 \pm 1.4) \times 10^{-20} \) m\(^2\)/W. The influence of higher-order nonlinearities such as \( χ^5 \) was assessed, showing no significant contribution within the examined intensity range. This work paves the way for the use of low-power and high-repetition-rate systems for characterizing third-order nonlinear optical materials. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_02944 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Nonlinear optical refractive index measurements of pure water via Z-scan technique at 800 nm Betka, Ilyes Optics The determination of the nonlinear optical coefficient \( n_2 \) of pure water is of great interest for applications such as imaging biological systems, performing femtosecond laser surgery, and underwater ablation. Traditionally, probing third-order nonlinearity while eliminating the thermo-optic effect requires high pulse energy and low repetition rate laser sources. In this article, a low-cost, simple, and versatile third-order nonlinear characterization technique for the Z-scan closed-aperture mode has been developed to determine the nonlinear refractive index of pure water at 800 nm, with a pump duration of 140 fs and a repetition rate of 80 MHz. Experimental results reveal an \( n_2 \) value of \( (8 \pm 1.4) \times 10^{-20} \) m\(^2\)/W. The influence of higher-order nonlinearities such as \( χ^5 \) was assessed, showing no significant contribution within the examined intensity range. This work paves the way for the use of low-power and high-repetition-rate systems for characterizing third-order nonlinear optical materials. |
| title | Nonlinear optical refractive index measurements of pure water via Z-scan technique at 800 nm |
| topic | Optics |
| url | https://arxiv.org/abs/2502.02944 |