Luminescence in the fluoride-containing phosphate-based glasses: a possible origin of their high resistance to nanosecond pulse laser-induced damage.

Pengfei Wang,Chaoqi Hou,Haitao Guo,Zhiwei Zhou,Bo Peng,Fei Gao,Yantao Xu,Min Lu

doi:10.1038/srep08593

Abstract

Fusion power offers the prospect of an almost inexhaustible source of energy for future generations. It was reported that fusion fuel gains exceeding unity on the National Ignition Facility (NIF) were achieved, but so far great deal of scientific and engineering challenges have to be overcome for realizing fusion power generation. There is a bottleneck for color-separation gratings in NIF and other similar inertial confinement fusion (ICF) lasers. Here we show a series of high performance phosphate-based glasses that can transmit the third harmonic frequency (3ω) laser light with high efficiency meanwhile filter the fundamental (1ω) and the second harmonic frequency (2ω) laser lights through direct absorption, and especially they exhibit excellent damage threshold induced by nanosecond pulse laser compared with that of the fused silica used in NIF. Yellowish-orange fluorescence emits during the laser-material interaction process, and it can be tailored through regulating the glass structure. Study on its structural origin suggests that the fluorescence emission is a key factor that conduces to the high laser-induced damage resistance of these glasses. The results also indicated the feasibility of utilizing these high performance glasses in novel color separation optics, allowing novel design for the final optics assembly in ICF lasers.

Highlights

Luminescence in the fluoride-containing phosphate-based glasses: A possible origin of their high resistance to nanosecond pulse laser-induced damage
It was reported that fusion fuel gains exceeding unity on the National Ignition Facility (NIF) were achieved, but so far great deal of scientific and engineering challenges have to be overcome for realizing fusion power generation
We show a series of high performance phosphate-based glasses that can transmit the third harmonic frequency (3v) laser light with high efficiency filter the fundamental (1v) and the second harmonic frequency (2v) laser lights through direct absorption, and especially they exhibit excellent damage threshold induced by nanosecond pulse laser compared with that of the fused silica used in NIF

Summary

Introduction

Luminescence in the fluoride-containing phosphate-based glasses: A possible origin of their high resistance to nanosecond pulse laser-induced damage. The envelope of unconverted light extends out from target chamber center, potentially affecting the target back lighter structures and diagnostics[12,13] Besides these technical problems, the diffractive optical elements used in the FOA that are made from fused silica glass are always damaged by stimulated Brillouin scattering under high laser fluence[14]. To fabricate the large aperture (43 cm 3 43 cm) optics in the FOA, such as color-separation gratings and silica wedge focus lens, must suffer most harsh processing techniques[11] and is time consuming and www.nature.com/scientificreports expensive These related problems due to existing color phase separation technique, together with the limit of improving the laser damage resistance of the fused silica glasses, has become one of the most significant bottlenecks to further increase the output fluence of ICF laser systems. To develop replacement options for fused silica will allow more novel designs for the FOA15

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Conclusion