The tolerances in manufacturing of fully dielectric diffraction gratings based on the leaky-mode resonance in the $-1$st diffraction order can be challenging, especially if the grating design exhibits high diffraction efficiency (DE) only within a comparatively narrow spectral bandwidth. To gain improved control on the spectral bandwidth exhibiting high DE, we implemented a two-step etching approach within the fabrication process of the grating. First, a dry and anisotropic etching step was used for pre-shaping the grating, followed by iterative isotropic wet-etching steps using an alkaline solution (KOH) at a temperature of 90°C to adjust the maximum efficiency around the desired wavelength with high precision. This straightforward method gave us very good control on tailoring the DE as a function of the wavelength and led to the demonstration of DEs as high as $99.7\pm 0.2\%$ in the $-1$st diffraction order at a wavelength of 1030 nm and of $>99\%$ in the wavelength range between 1020 and 1070 nm. The gratings were used as cavity end mirrors of an Yb:YAG thin-disk laser, generating an output power of 145 W in fundamental mode operation (${\mathrm{M}}^2<1.1$).

中文翻译：

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用于高效率制造高效衍射光栅的修整方法

基于泄漏模式共振的全介质衍射光栅的制造公差。 $-\mathrm{1个}$st衍射级可能具有挑战性，特别是如果光栅设计仅在相对较窄的光谱带宽内显示出高衍射效率（DE）时。为了更好地控制展现高DE的光谱带宽，我们在光栅的制造过程中实施了两步蚀刻方法。首先，使用干法各向异性蚀刻步骤对光栅进行预成形，然后在90°C温度下使用碱性溶液（KOH）进行迭代各向同性湿法蚀刻步骤，以最大程度地调节所需波长附近的最大效率。精确。这种简单的方法使我们能够很好地控制将DE定制为波长的函数，并导致DE的演示高达$99.7\pm 0.2％$ 在里面 $-\mathrm{1个}$在1030 nm和 $>99％$在1020至1070 nm之间的波长范围内 光栅用作Yb：YAG薄盘激光器的腔端镜，在基本模式下产生145 W的输出功率（${\mathrm{中号}}^{2个}<1.1$）。