title: Guided wave microscopy: mastering the inverse problem.
abstract: Surface plasmon microscopy is widely recognized for its high sensitivity to nanoscale dielectric or metallic structures confined in a close neighborhood of a gold surface. Recently, its coupling to high-numerical-aperture objective lenses pushed its resolution down to the diffraction limit. Here, we show that the same microscope configuration can be used to excite standing guided waves in asymmetric slabs, which definitely extends the range of applications of this type of microscopy from nano- to microscale structure imaging. We demonstrate experimentally on PPMA films that the V(Z) response of a scanning surface plasmon microscope can be Fourier inverted in order to obtain the reflectivity curve R(ν). When the guided waves are excited, R(ν) shows a finite number of sharp peaks corresponding to quantified guiding modes from which one can extract both the refractive index (RI) and the thickness of the layer at the point focused by the microscope. This device can thus be used to reconstruct RI and thickness contours of dielectric samples with a high spatial resolution.
authors.forename: Lotfi
authors.initials: L
authors.lastname: Berguiga
authors.forename: Elise
authors.initials: E
authors.lastname: Boyer-Provera
authors.forename: Cristina
authors.initials: C
authors.lastname: Martinez-Torres
authors.forename: Juan
authors.initials: J
authors.lastname: Elezgaray
authors.forename: Alain
authors.initials: A
authors.lastname: Arneodo
authors.forename: Françoise
authors.initials: F
authors.lastname: Argoul