A comprehensive study and design of air-clad suspended ridge diamond waveguides for operation across the 2.5–16 m spectral range is presented, specifically targeting nanocrystalline diamond (NCD) thin films directly grown on silicon substrates. Three film thicknesses of 520, 1000 and 2000 nm are considered, to cover overlapping sub-bands of 2.5–5, 4–9 and 8–16 m, respectively. Within each sub-band, the waveguide dimensions for single mode quasi-TE operation are found and the waveguide material losses and bending losses are estimated at each design point. In addition, in each case the minimum required undercut depth and etch hole placement for optical isolation of the waveguide mode from the silicon substrate is also quantified. We also estimate the losses associated with scattering from surface roughness, which is an unavoidable byproduct of the NCD thin film growth process. Our results indicate that despite the relatively low film thickness-to-wavelength ratio, mechanically stable waveguides with good optical confinement and low material and bending losses can be realised to cover the full 2.5–16 m range. In addition, scattering loss estimations predict a drastic drop in roughness-induced scattering losses above 6 m, even for relatively rough films. In addition to highlighting the utility of suspended NCD as a versatile platform for mid-infrared integrated photonics, the approaches and results presented here can be used to inform the design of suspended air-clad waveguides in other material platforms.

用于跨 2.5-16 的空气包层悬脊金刚石波导的综合研究和设计 提出了 m 光谱范围，特别针对直接在硅基板上生长的纳米晶金刚石 (NCD) 薄膜。考虑了 520、1000 和 2000 nm 三种薄膜厚度，以覆盖 2.5-5、4-9 和 8-16 的重叠子带 m，分别。在每个子带内，找到单模准 TE 操作的波导尺寸，并在每个设计点估计波导材料损耗和弯曲损耗。此外，在每种情况下，用于波导模式与硅衬底的光学隔离所需的最小底切深度和蚀刻孔位置也被量化。我们还估计了与表面粗糙度散射相关的损失，这是 NCD 薄膜生长过程中不可避免的副产品。我们的结果表明，尽管膜厚波长比相对较低，但可以实现具有良好光学限制和低材料和弯曲损耗的机械稳定波导，以覆盖整个 2.5-16 米范围。此外，散射损失估计预测粗糙度引起的散射损失将急剧下降 6 m，即使对于相对粗糙的薄膜。除了强调悬浮 NCD 作为中红外集成光子学的多功能平台的实用性之外，这里介绍的方法和结果还可用于为其他材料平台中的悬浮空气包层波导的设计提供信息。