This work was supported by the US DOE Basic Science Ofﬁce Contract No. DE-FG02-07ER46406.
Physical Review B
Photoelectric emission, Waveguides, Thin films -- Surfaces, Photoemission
We report the visualization and quantitative analysis of electromagnetic surface fields at solid surfaces with the potential for λ/50 resolution. To illustrate this capability, we investigate patterns in two-photon photoemission images of light-diffracting structures in waveguiding, transparent thin films. The obtained micrographs show interference patterns between incident and guided light with a remarkable sensitivity to subwavelength features. We demonstrate that photoemission rates are directly related to the surface field strengths and develop a subwavelength method to calculate the surface fields from optical properties and surface topology based on the two-dimensional Kirchhoff diffraction integral. Calculated images based on this theoretical approach compare favorably to experimental electron micrographs.
Fitzgerald, J. P. S., Word, R. C., & Könenkamp, R. (2014). Subwavelength visualization of light in thin film waveguides with photoelectrons. Physical Review B, 89(19), 195129.