Second harmonic generation in the near field and far field: A sensitive tool to probe crystalline homogeneity

Abstract

Articles you may be interested inPotential-well depth at amorphous-LaAlO3/crystalline-SrTiO3 interfaces measured by optical second harmonic generation Appl. Phys. Lett.Local crystal analysis using near-field optical second harmonic microscopy: Application to thin ferroelectric films In order to probe crystalline orientation of Sr x Ba 1−x Nb 2 O 6 ͑SBN: x͒ thin film, we have developed a detection scheme based on a scanning near-field optical microscope ͑SNOM͒. It is used to image simultaneously the fundamental and the second harmonic generation ͑SHG͒ of light by the sample under pulsed laser illumination. We demonstrate on SBN thin films that an apertureless SNOM can dramatically improve the resolution and the sensitivity of SNOM-SHG. Tip direction and focalization are the two crucial parameters in the SNOM-SHG experiments. Moreover, we show the ability of our setup to separate near field from far field contribution to the SHG. This is indeed very helpful in order to measure surface-SHG coefficients.

Probing Ferroelectrics Using Optical Second Harmonic Generation

“…A second approach is akin to the apertureless NSOM (ANSOM) technique, the difference being that the setup is modified to collect the near‐field SHG signal, rather than the evanescent wave of the fundamental. In short, the fundamental light is focused on the sample, where the near‐field evanescent waves (both fundamental and second harmonic [SH]) are scattered by an oscillating metallic tip operating in tapping mode . The scattered near‐field and far‐field waves are then collected for both the fundamental and SH wave, and the near‐field contributions can be separated out by filtering the signals at the oscillation frequency of the tip [Fig.…”

Combined Apertureless Near-Field Optical Second-Harmonic Generation/Atomic Force Microscopy Imaging and Nanoscale Limit of Detection

“…1 Additionally, tips have been employed that locally distort or enhance the electric fields generated by the excitation source near the object under study (apertureless NSOM). [2][3][4] NSOM is well adapted for various gaseous and liquid environments, allowing in situ studies of chemical processes.…”

Near‐field microscopy and fluorescence spectroscopy: application to chromosomes labelled with different fluorophores

“…These limitations can be overcome by using scanning near‐field optical microscopy (SNOM) (Pohl et al , 1984) that allows a resolution in the hundreds (Dunn, 1999) or tens of nanometre scale (Kim et al , 2004; Mahieu‐Williame et al , 2007). Moreover, when an SNOM probe is used as a nanosource of light, it reduces the dimension of the illumination zone and the time of exposure and, as a consequence, photobleaching of fluorescent labels also is decreased.…”