Antenna effects in terahertz apertureless near-field optical microscopy
نویسندگان
چکیده
We have performed measurements on terahertz (THz) apertureless near-field microscopy that show that the temporal shape of the observed near-field signals is approximately proportional to the time-integral of the incident field. Associated with this signal change is a bandwidth reduction by approximately a factor of 3 which is observed using both a near-field detection technique and a far-field detection technique. Using a dipole antenna model, it is shown how the observed effects can be explained by the signal filtering properties of the metal tips used in the experiments. © 2004 American Institute of Physics. [DOI: 10.1063/1.1797554]
منابع مشابه
Propagation effects in apertureless near-field optical antennas
We report a direct observation of the electromagnetic wave propagation on optical antennas. A free-space broadband terahertz pulse is coupled into a propagating mode along the shaft of an optical antenna acting as an apertureless near-field probe. We determine the spatial extent of this guided mode and its velocity. In addition, we consider the possibility of multiply reflected modes propagatin...
متن کاملMeasurement and calculation of the near field of a terahertz apertureless scanning optical microscope
We present measurements and calculations of the terahertz (THz) electric field measured in the near field of a metal tip used in THz apertureless near-field optical microscopy (THz-ANSOM). An analytical model in which we treat the metal tip as a linear wire antenna allows us to predict almost all of the features observed in the measurements, such as the relatively slow decay of the near-field a...
متن کاملA study of background signals in terahertz apertureless near-field microscopy and their use for scattering-probe imaging
Apertureless near-field microscopy is an imaging technique in which a small metal tip is held close to a surface, converting evanescent waves to propagating waves and permitting extreme subwavelength spatial resolution. This technique has recently been adapted for use in the terahertz region of the spectrum. Here, the interpretation of the measured signals and the suppression of background scat...
متن کاملField enhancement in apertureless near-field scanning optical microscopy.
The near field of an apertureless near-field scanning optical microscopy probe is investigated with a multiple-multipole technique to obtain optical fields in the vicinity of a silicon probe tip and a glass substrate. The results demonstrate that electric field enhancements of >15 relative to the incident fields can be achieved near a silicon tip, implying intensity enhancements of several orde...
متن کاملHeterodyne apertureless near-field scanning optical microscopy on periodic gold nanowells.
Heterodyne detection for apertureless near-field scanning optical microscopy was used to study periodic gold nanowell arrays. Optical near-field amplitude and phase signals were obtained simultaneously with the topography of the gold nanowells and with different polarizations. Theoretical calculations of the near-fields were consistent with the experiments; in particular, the calculated amplitu...
متن کامل