Anisotropic two-photon absorbers measured by the Z-scan technique and its application in laser beam shaping

Hu, Yueqiu; Gu, Bing; Wen, Bang Chun; Lv, Changgui; Rui, Guanghao; He, Jun; Cui, Yiping

doi:10.1364/josab.383899

Cited by 7 publications

(4 citation statements)

References 43 publications

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“…For the sake of simplicity, at the 800-nm laser wavelength, ZnSe and GaP are regarded to have a zero linear absorption coefficient. Thus, the transmitted intensity through the sample with a length of L is expressed as [21,22]…”

Section: Resultsmentioning

confidence: 99%

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Significant intensity dependence of anisotropic two-photon absorption in ZnSe and GaP

Ye¹,

Huang²

2023

Laser Phys.

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Using polarized femtosecond laser transmission measurements toward (100), (110), (111) ZnSe, and (100) GaP, we show that in a wide laser irradiation intensity range over two orders of magnitude before the laser damage threshold, a periodic amplitude modulation always appears clearly in the angle-dependent two-photon absorption (TPA) curves for (100), (110) ZnSe, and (100) GaP. It also exhibits a close connection between the orientation-dependent TPA and the ionic bonding symmetrical characteristics of specific crystal plane, thus revealing the origin of the orientation dependence of nonlinear absorption in the strong field laser-solid interaction. Interestingly, the modulation amplitudes of orientation-dependent TPA exhibit significant intensity dependence, with the maxima occurring around 1011 W cm−2. For the orientation-dependent nonlinear absorption in solids, such a nonmonotonic relationship between the irradiation intensity and the modulation amplitude has not been revealed previously in the near-damage-threshold regime by direct transmission measurements. In particular, with the intensity approaching the laser damage threshold, the significant descending trend of modulation amplitude confirms the consistent characteristics of saturation or even attenuation for the orientation dependence of TPA in the two crystals, which might be considered as a product of absorption saturation phenomenon of TPA at high irradiation intensity and would provide new understanding about the orientation-dependent TPA in the near-damage-threshold regime.

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Section: Resultsmentioning

confidence: 99%

“…Considering the Gaussian distribution of the irradiation laser beam in space and time, and by integrating spatially and temporally of equation ( 2), the intensity-dependent normalized energy transmittance can be expressed as [21,22]…”

Section: Resultsmentioning

confidence: 99%

Significant intensity dependence of anisotropic two-photon absorption in ZnSe and GaP

Ye¹,

Huang²

2023

Laser Phys.

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“…Z-scan [49][50][51][52]: The Z-scan technique is a direct way of recording nonlinear absorption, which is detected by moving the sample along the axis of a focused laser beam and observing changes in the transmittance, either of the whole beam (so-called open-aperture scan) or by probing only the central part of the beam with an aperture placed in the far field (closed-aperture scan) [49,[53][54][55][56]. The advantage of the technique is that materials with lowfluorescence efficiency can be studied, since emission from the sample is not required, the data processing does not require calibration by nonlinear absorption standards (although relative measurements can be readily performed), and the closed-aperture version of the measurement is sensitive to both the nonlinear absorption and nonlinear refraction.…”

Section: Evaluation Of Parameters Relevant For the Use Of Photosensitizersmentioning

confidence: 99%

Prospects for More Efficient Multi-Photon Absorption Photosensitizers Exhibiting Both Reactive Oxygen Species Generation and Luminescence

et al. 2021

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The use of two-photon absorption (TPA) for such applications as microscopy, imaging, and photodynamic therapy (PDT) offers several advantages over the usual one-photon excitation. This creates a need for photosensitizers that exhibit both strong two-photon absorption and the highly efficient generation of reactive oxygen species (ROS), as well as, ideally, bright luminescence. This review focuses on different strategies utilized to improve the TPA properties of various multi-photon absorbing species that have the required photophysical properties. Along with well-known families of photosensitizers, including porphyrins, we also describe other promising organic and organometallic structures and more complex systems involving organic and inorganic nanoparticles. We concentrate on the published studies that provide two-photon absorption cross-section values and the singlet oxygen (or other ROS) and luminescence quantum yields, which are crucial for potential use within PDT and diagnostics. We hope that this review will aid in the design and modification of novel TPA photosensitizers, which can help in exploiting the features of nonlinear absorption processes.

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“…Due to the band structure and the point-group symmetry of the crystal, the nonlinear optical response is usually anisotropic. The polarization-structured light fields interacting with anisotropic nonlinear media give rise to novel nonlinear optical effects and applications, including the redistribution of the spin angular momentum [17,18], enhancement of optical limiting effects [19], controllable field collapse and subsequent filamentation [20], and laser beam shaping [21].…”

Section: Introductionmentioning

confidence: 99%

Polarization rotation and singularity evolution of fundamental Poincaré beams through anisotropic Kerr nonlinearities

Wen

Rui

et al. 2020

J. Opt.

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We report a theoretical investigation on polarization rotation and singularity evolution of focused fundamental Poincaré beams in free-space propagation and through isotropic and anisotropic Kerr nonlinear media. It is found that the optical nonlinearity enhances the polarization rotation of the focused beams during propagation. Furthermore, the anisotropy of optical nonlinearity causes the symmetry breaking of the polarization distribution. Further studies show that the C-point and L-line singularities of the lemon Poincaré beams do not change while propagating in free space or through the isotropic nonlinear Kerr medium. Interestingly, the anisotropic Kerr nonlinearity evokes the C-point singularity splitting, and the distortion and birth of L-line singularities. However, the total singularity index always remains the conservation within the light field, regardless of the optical nonlinearity.

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Anisotropic two-photon absorbers measured by the Z-scan technique and its application in laser beam shaping

Cited by 7 publications

References 43 publications

Significant intensity dependence of anisotropic two-photon absorption in ZnSe and GaP

Significant intensity dependence of anisotropic two-photon absorption in ZnSe and GaP

Prospects for More Efficient Multi-Photon Absorption Photosensitizers Exhibiting Both Reactive Oxygen Species Generation and Luminescence

Polarization rotation and singularity evolution of fundamental Poincaré beams through anisotropic Kerr nonlinearities

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