A study was conducted on the nonlinear characteristics of Rhodamine B (Rh B) doped with the poly methyl methacrylate (PMMA) using the Z-scan technique with both closed and open aperture. Different concentrations of Rhodamine B thin films were prepared using the casting method. The nonlinear absorption, nonlinear refraction, optical limiting, and third-order susceptibility of the prepared samples were studied under the influence of the 650 nm diode laser. The results showed that the samples exhibited self-defocusing, with a negative nonlinear refractive index (n2) is approximate of 10–6 cm2 /watt for the three concentrations. Additionally, the prepared samples exhibited two-photon absorption, in which the nonlinear absorption coefficient (β) ranged between 0.55 <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12596_2025_2614_Article_IEq1.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="47" /> </InlineMediaObject> <EquationSource Format="TEX">$\times {10}^{-2}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>-</mo> <mn>2</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation>–0.868 <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12596_2025_2614_Article_IEq2.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="47" /> </InlineMediaObject> <EquationSource Format="TEX">$\times {10}^{-2}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>-</mo> <mn>2</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> cm /watt. The highest concentration sample showed the highest nonlinearity with third-order susceptibility (χ3) of about 2.87 <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="12596_2025_2614_Article_IEq3.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="47" /> </InlineMediaObject> <EquationSource Format="TEX">$\times {10}^{-2}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>-</mo> <mn>2</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> esu. The three prepared films demonstrated optical limiting (OL) behavior. This makes them suitable for use as optical limiters and energy or power stabilizers, which have useful applications for sensing, especially for the human eye.

Nonlinear third-order characteristics and optical limiting of rhodamine B-PMMA doped films with varying concentrations using the Z-scan technique

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发表日期：

2025年3月7日

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Amal F. Jaffar,
Israa N. Akram,
Hamid k. Al-zaidi

摘要

A study was conducted on the nonlinear characteristics of Rhodamine B (Rh B) doped with the poly methyl methacrylate (PMMA) using the Z-scan technique with both closed and open aperture. Different concentrations of Rhodamine B thin films were prepared using the casting method. The nonlinear absorption, nonlinear refraction, optical limiting, and third-order susceptibility of the prepared samples were studied under the influence of the 650 nm diode laser. The results showed that the samples exhibited self-defocusing, with a negative nonlinear refractive index (n₂) is approximate of 10^–6 cm² /watt for the three concentrations. Additionally, the prepared samples exhibited two-photon absorption, in which the nonlinear absorption coefficient (β) ranged between 0.55 $\times {10}^{-2}$ $\times 10^{- 2}$ –0.868 $\times {10}^{-2}$ $\times 10^{- 2}$ cm /watt. The highest concentration sample showed the highest nonlinearity with third-order susceptibility (χ3) of about 2.87 $\times {10}^{-2}$ $\times 10^{- 2}$ esu. The three prepared films demonstrated optical limiting (OL) behavior. This makes them suitable for use as optical limiters and energy or power stabilizers, which have useful applications for sensing, especially for the human eye.