Quantitative amplitude and phase measurement by use of a heterodyne scanning near-field optical microscope

Abstract

A coherent photon scanning tunneling microscope is presented. The setup employs heterodyne interferometry, allowing both the phase and the amplitude of the optical near field to be measured. Experimental results of measurements on a standing evanescent wave reveal the high resolution that is obtainable with such an approach. In fact we have measured the amplitude and the phase of the near field, with a resolution of 1.6 nm between sample points.

Measuring amplitude and phase distribution of fields generated by gratings with sub-wavelength resolution

“…Once the tip approach is done, the AFM feedback (contact mode) is switched off and the scan (in XY or XZ planes) is accomplished by the x-y-z stage. The optical scanning probe microscope is combined with a heterodyne interferometer in order to get the phase information [4]. The light collected by the fiber probe is combined in a fiber coupler with a frequency shifted reference wave, producing the beat signal required for the heterodyne detection.…”

“…Measurements of amplitude Aðx xÞ and phase /ðx xÞ with a heterodyne scanning probe microscope [1][2][3][4] have been made in the optical field diffracted by periodic microstructures, in particular a holographically recorded 1 lm pitch grating. Most SNOM measurements are done at constant height (or constant intensity) in the X-Y plane (parallel to the surface) above the samples.…”

Using a quantum well heterostructure to study the longitudinal and transverse electric field components of a strongly focused laser beam

“…As an alternative to provide for the necessary high numerical aperture detection, a scanning near field optical microscope ͑SNOM͒ fiber tip 10 can also be used. In principle, it is even possible to measure phase and amplitude with a SNOM, 11 however, the sensitivity for longitudinal and transverse components can differ 12 and this discrepancy needs to be taken into account for the interpretation of the results.…”

Characterizing ultrashort optical pulses using second-order nonlinear nanoprobes

“…A NSOM fiber probe was utilized to measure the amplitude and the phase of optical fields by heterodyne detection, 7 visualize the propagation of femtosecond pulses 8 through photon scanning tunneling microscopy, and characterize ultrashort pulses in the vicinity of the focal point of a lens by interferometry. 9 Individual second harmonic nanocrystal dispersed on a substrate was also used to characterize focused ultrashort pulses through collinear frequency resolved optical gating ͑FROG͒ measurement.…”