Observation of nonlinear bands in near-field scanning optical microscopy of a photonic-crystal waveguide

Abstract

We have measured the photonic bandstructure of GaAs photonic-crystal waveguides with high energy and momentum resolution using near-field scanning optical microscopy. Intriguingly, we observe additional bands that are not predicted by eigenmode solvers, as was recently demonstrated by Huisman et al. [Phys. Rev. B 86, 155154 (2012)]. We study the presence of these additional bands by performing measurements of these bands while varying the incident light power, revealing a non-linear power dependence. Here, we demonstrate experimentally and theoretically that the observed additional bands are caused by a waveguide-specific nearfield tip effect not previously reported, which can significantly phase-modulate the detected field.

Phase imaging and detection in pseudo-heterodyne scattering scanning near-field optical microscopy measurements

“…This is possible because s-SNOM combines the high spatial resolution of atomic force microscopy (AFM) with additional illumination techniques to bypass the diffraction limit [1]. This has led to the popularity of s-SNOMs in recent years for imaging and obtaining optical information from structures such as nanoparticles [2], photonic-crystal waveguides [3], nanotubes [4], and even biomedical samples [5]. Our interest in s-SNOM is motivated by the study of near-field patterns produced by resonating metallic structures and optical antennas in the infrared [6,7].…”