arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.14013cond-mat.mtrl-sciastro-ph.IMphysics.optics
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非晶Ta2O5和TiO2:Ta2O5薄膜的光散射与退火温度的关系

Measurements of Optical Scatter Versus Annealing Temperature for Amorphous Ta2O5 and TiO2:Ta2O5 Thin Films

Elenna M. Capote, Amy Gleckl, Jazlyn Guerrero, Michael Rezac, Robert Wright, Joshua R. Smith

摘要:

由非晶氧化物薄膜形成的光学膜在精密测量中有许多应用。高级激光干涉仪引力波天文台(LIGO)和高级处女座使用SiO $_2$(二氧化硅)和TiO $_2$:Ta $_2$ O $_5$(二氧化钛掺杂的钽)涂层,并在沉积后退火至500 $^\circ$ C,以实现低热噪声和低光吸收。这些涂层的光散射是限制探测器灵敏度的关键因素。本文描述了在熔融石英衬底上离子束溅射的单层薄膜的光散射测量:两个样品的Ta $_2$ O $_5$和两个样品的TiO $_2$:Ta $_2$ O $_5$。在12.8 $^\circ$的固定散射角下使用成像散射仪,在真空中沉积后退火至500 $^\circ$ C期间评估每个样品的光学散射的原位变化。在退火过程中,观察到四个涂覆的光学器件中的三个的散射降低,对于氧化钽降低25-30 $\%$,对于二氧化钛掺杂的氧化钽降低高达74 $\%$,而来自第四个样品的散射保持恒定。真空退火前后进行的角度分辨散射测量表明,四个样品中有三个有所改善。这些结果表明,单层氧化钽和掺杂氧化钛的氧化钽薄膜在真空中的沉积后高温退火不会导致散射的增加,并且实际上可以改善它们的散射。

英文摘要:

Optical coatings formed from amorphous oxide thin films have many applications in precision measurements. The Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo use coatings of SiO$_2$ (silica) and TiO$_2$:Ta$_2$O$_5$ (titania doped tantala) and post-deposition annealing to 500$^\circ$C to achieve low thermal noise and low optical absorption. Optical scattering by these coatings is a key limit to the detectors' sensitivity. This paper describes optical scattering measurements for single-layer ion-beam-sputtered thin films on fused silica substrates: two samples of Ta$_2$O$_5$ and two of TiO$_2$:Ta$_2$O$_5$. Using an imaging scatterometer at a fixed scattering angle of 12.8$^\circ$, in-situ changes in the optical scatter of each sample were assessed during post-deposition annealing to 500$^\circ$C in vacuum. The scatter of three of the four coated optics was observed to decrease during the annealing process, by 25-30$\%$ for tantala and up to 74$\%$ for titania-doped tantala, while scatter from the fourth sample held constant. Angle-resolved scatter measurements performed before and after vacuum annealing suggests some improvement in three of four samples. These results demonstrate that post-deposition high-temperature annealing of single-layer tantala and titania-doped tantala thin films in vacuum does not lead to an increase in scatter, and may actually improve their scatter.

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