An approach to spectroscopy and phase measurements in scanning plasmon near-field microscopy

A new optical setup for plasmon near-field optical microscopes is introduced which allows to improve the signal/background ratio independently of the wavelength used and therefore makes the spectroscopy feasible. Calculated and experimental examples demonstrate this improvement obtained by addition of ellipsometric components. Furthermore, a first measurement in combination with a scanning tunnelling microscope shows that it is possible to extrude phase information from this setup as well.