Fundamental properties of an optical waveguide are mainly related to its guided modes and associated loss, dispersion, polarization and nonlinearity. Single-mode and single-polarization waveguiding has long been of interest, i.e., so-called truly single mode. We propose SiC- and diamond-based waveguides, which are truly single-mode and simultaneously dispersion-flattened. This is preferred for broadband nonlinear applications, such as octave-spanning supercontinuum and frequency comb generation. An ultra-low and flat dispersion profile with four zero-dispersion wavelengths (ZDWs) can be obtained over an octave-spanning bandwidth from 1.8 to 3.6 μm. Meanwhile, only TE₀₀ mode is supported in the proposed waveguide over the low-dispersion bandwidth. Scattering loss of the waveguide is greatly reduced by 8.6 times, compared to a standard strip waveguide. Fabrication of the proposed waveguide is easier than previous dispersion-tailored waveguides, without dry etching SiC and diamond. It is expected that the proposed waveguides can find applications in nonlinear photonics, optomechanics and quantum optics.

光波导的基本特性主要与其导模和相关的损耗、色散、偏振和非线性有关。长期以来，单模和单极化波导一直受到关注，即所谓的真正单模。我们提出了基于 SiC 和金刚石的波导，它们是真正的单模，同时色散平坦。这是宽带非线性应用的首选，例如跨倍频程超连续谱和频率梳生成。可以在 1.8 到 3.6 μm 的倍频程跨度带宽上获得具有四个零色散波长 (ZDW) 的超低且平坦的色散曲线。同时，只有TE ₀₀模式在低色散带宽上的建议波导中得到支持。与标准条形波导相比，波导的散射损耗大大降低了 8.6 倍。所提出的波导的制造比以前的色散定制波导更容易，无需干蚀刻 SiC 和金刚石。预计所提出的波导可以在非线性光子学、光机械和量子光学中找到应用。