Thermal analysis of multilayer dielectric grating with high power laser irradiation

Wang, Hanbin; Yuan, Zhijun; Ye, Song; Yang, Yifeng; Liu, Meizhong; He, Bing; Zhou, Jun; Wei, Tai‐Huei

doi:10.1063/5.0006249

Cited by 4 publications

(1 citation statement)

References 26 publications

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“…For SBC system, the combined beam quality experiences degradation due to dispersion effect, thermal distortion of the optical elements, beam pointing deviation, and etc. Among these beam degradation causes, the thermal distortion and beam pointing deviation have been investigated in [19][20][21][22][23][24][25][26] correspondingly. However, there are few analyses for dispersion effect determined by the spectral characteristic of the laser beamlets, which would induce degradation of combined beam quality M 2 in the grating dispersion plane.…”

Section: Introductionmentioning

confidence: 99%

Theoretical analysis of beam quality degradation induced by laser spectral characteristics in spectral beam combining system

Xian¹,

Yang²,

Li³

et al. 2022

J. Opt.

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We establish a model based on the dispersion of the diffractive grating to investigate the influence of the spectral envelope and wavelength stability on the combined beam quality of the spectral beam combining system. We obtain the analytic expressions of combined beam quality corresponding to the second-moment-spectral width of the beamlets, which can be used to forecast the combined beam quality for any integrable spectral envelope shape of beamlets in a spectral beam combining system. Additionally, we find that the center wavelength shift of beamlets has a significant impact on the combined beam quality. The second-moment-based width of the center wavelength shift distribution among all beamlets should be less than 0.5 times the spectral width. Here, the spectral width is the weighted root mean square of all beamlets' spectral width, where the weight is the power of each single channel.

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Section: Introductionmentioning

confidence: 99%

Theoretical analysis of beam quality degradation induced by laser spectral characteristics in spectral beam combining system

Xian¹,

Yang²,

Li³

et al. 2022

J. Opt.

Self Cite

View full text Add to dashboard Cite

show abstract

Simulation and experimental study of laser-induced thermal deformation of spectral beam combination grating

Wang

Yang

et al. 2020

Opt. Express

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The multilayer dielectric (MLD) grating is a critical device for combining multiple laser beams into a single beam in a spectral beam combining (SBC) system. We established a theoretical thermal deformation model of the laser-irradiated MLD grating. Thermal deformation on the surface of the grating is simulated according to a series of parameters including the laser irradiation time, laser power density, and substrate size. To verify the model, we exposed a 960 l/mm, 50×50×1.5 mm3 grating to a laser power density of 3.61 kW/cm2 and observed the temperature change. We used a Twyman-Green interferometer to measure the interference fringes on the grating surface. Based on the Fourier-transform method and a Zernike polynomial fitting method, the real-time grating surface profile is reconstructed. The results show that substrate thickness increase or area decrease can reduce thermal deformation, the average decreases are 18.3% and 19.9%, respectively. The discussion and analysis of the grating thermal deformation are potentially valuable for designing grating to decrease the thermal deformation and improve the combined beam quality of a SBC system.

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Analysis method of point defects evolution in fused silica under multi-pulse nanosecond laser irradiation

Huang,

Mu,

Gao

et al. 2024

Opt. Express

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Although no optically visible damage is produced in the fused silica under laser irradiation below its laser-induced damage threshold (LIDT), defect proliferation may occur due to the evolution of its internal atomic structure. The escalation in defect content leads to heightened absorption, and resulting in the degradation of the optical performance of the optics. In recent decades, there have been a lot of experimental studies on laser-induced damage and laser conditioning, but there is still a great lack of in-depth understanding and theoretical analysis of the evolution process of point defects in fused silica. In this study, the emphasis is on the evolution of point defects and fatigue damage in fused silica under multi-pulse nanosecond laser irradiation. To address this, a point-defect evolution model is developed, and the coupled evolution law of temperature and defect during laser irradiation is derived by integrating it with a numerical model. The results demonstrate that the model effectively predicts the defect evolution of fused silica under laser irradiation and facilitates the prediction of fatigue damage. It is revealed that the rate of defect evolution in fused silica is more influenced by temperature than stress, and a temperature threshold can be used to judge the condition of damage occurrence. Furthermore, through an analysis of the effect of laser fluence on defect relaxation rate, a defect relaxation method employing variable laser fluence was proposed. This study provides a reliable theoretical analysis method for understanding the fatigue damage induced by multi-pulse laser irradiation in fused silica and offers a new perspective for the annealing treatment of point defects in fused silica.

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Thermal analysis of multilayer dielectric grating with high power laser irradiation

Cited by 4 publications

References 26 publications

Theoretical analysis of beam quality degradation induced by laser spectral characteristics in spectral beam combining system

Theoretical analysis of beam quality degradation induced by laser spectral characteristics in spectral beam combining system

Simulation and experimental study of laser-induced thermal deformation of spectral beam combination grating

Analysis method of point defects evolution in fused silica under multi-pulse nanosecond laser irradiation

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