Visualization of Isofrequency Contours of Strongly Localized Waveguide Modes in Planar Dielectric Structures

An experimental method has been proposed to study the dispersion properties of optical surface and waveguide modes in planar structures. An experimental setup involves a microscope with a high numerical aperture objective and a hemispherical solid immersion lens made of zinc selenide in contact with the sample surface. The reflection from the sample is detected in the back focal plane of the system. Such a configuration makes it possible to study strongly localized states with an effective refractive index up to 2.25 in the visible and near infrared spectral ranges. For a thin silicon layer deposited on a glass substrate, the possibility of visualization of isofrequency contrours with polarization resolution and the reconstruction of dispersion of waveguide modes depending on the direction of their propagation has been demonstrated.