Surface waves such as plasmon, exciton, or phonon polaritons as well as guided modes supported by various planar structures attract particular attention due to their capability of capturing and carrying the optical signals in 2D and 1D systems. An important characteristic of such waves is their dispersion ω(k_x, k_y), which can be designed on demand by nanostructuring of planar layered systems to obtain photonic crystal slabs and metasurfaces. Engineering the dispersion of surface waves gives rise to such exciting optical effects as transition from positive to negative refraction or from elliptic to hyperbolic dispersion, self-collimation, and diffraction-free propagation of surface waves. Along with the real part of the wavevector responsible for the phase of a propagating surface wave, a crucially important parameter for the applications is its propagation length that is related to the intrinsic losses of the mode. We propose an experimental approach allowing for the extraction of the full complex dispersion of optical surface waves and guided modes. The method relies on angle-resolved attenuated total internal reflection spectroscopy. In such a setup, scanning the air gap between the sample and a solid immersion lens yields controllable tuning of the coupling between the surface waves and the free space. In the experiment, we identify the regime of critical coupling of light to waveguide modes of a planar silicon slab and use it to extract their intrinsic losses and thus the propagation lengths in a broad spectral range. Our approach is a powerful tool for studies of light and hybrid light-matter surface waves of various kinds and may find its applications in the development of on-chip optoelectronic and nanophotonic devices.

等离子激元、激子或声子极化激元等表面波以及由各种平面结构支持的导模因其在二维和一维系统中捕获和携带光信号的能力而受到特别关注。这种波的一个重要特征是它们的色散 ω( k _x , k _y)，可以通过平面分层系统的纳米结构按需设计，以获得光子晶体板和超表面。设计表面波的色散会产生令人兴奋的光学效应，例如从正折射到负折射或从椭圆形到双曲线色散的转变、自准直和表面波的无衍射传播。除了负责传播表面波相位的波矢量的实部外，应用的一个至关重要的参数是其传播长度，它与模式的固有损耗有关。我们提出了一种实验方法，允许提取光学表面波和导模的完整复杂色散。该方法依赖于角分辨衰减全内反射光谱。在这样的设置中，扫描样品和固体浸没透镜之间的气隙可以对表面波和自由空间之间的耦合进行可控调整。在实验中，我们确定了光与平面硅板的波导模式的临界耦合机制，并使用它来提取它们的固有损耗，从而提取宽光谱范围内的传播长度。我们的方法是研究各种光和混合光物质表面波的强大工具，可能会在片上光电和纳米光子器件的开发中得到应用。我们确定了光与平面硅板的波导模式的临界耦合状态，并使用它来提取它们的固有损耗，从而提取宽光谱范围内的传播长度。我们的方法是研究各种光和混合光物质表面波的强大工具，可能会在片上光电和纳米光子器件的开发中得到应用。我们确定了光与平面硅板的波导模式的临界耦合状态，并使用它来提取它们的固有损耗，从而提取宽光谱范围内的传播长度。我们的方法是研究各种光和混合光物质表面波的强大工具，可能会在片上光电和纳米光子器件的开发中得到应用。