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In-line interferometer for broadband near-field scanning optical spectroscopy
Optics Express
|August 10, 2017
Summary
This study introduces a novel in-line interferometer for broad-bandwidth near-field scanning optical spectroscopy. The method effectively amplifies near-field signals and suppresses background noise for clearer spectral measurements.
Area of Science:
- Optics
- Spectroscopy
- Nanotechnology
Background:
- Scattering-type scanning near-field optical spectroscopy (s-SNOM) often suffers from background noise.
- Unwanted scattering from the probe shaft and sample obscures the true near-field signal.
Purpose of the Study:
- To develop a novel approach for broad-bandwidth near-field scanning optical spectroscopy.
- To enhance near-field signal detection by suppressing background noise.
- To enable rapid acquisition of pure near-field spectra.
Main Methods:
- Utilizing an in-line interferometer for homodyne mixing of near-field and reference fields.
- Employing a semi-transparent gold layer to increase sample-reflected light as a reference field.
- Using a monochromator and fast line camera for rapid spectral acquisition.
Main Results:
- Demonstrated efficient suppression of unwanted background signals in near-field measurements.
- Achieved amplification of the near-field signal in the visible and near-infrared spectral range.
- Successfully measured pure near-field spectra using the developed technique.
Conclusions:
- The in-line interferometer approach significantly improves near-field signal clarity.
- The developed method is a crucial step towards advanced broad-bandwidth near-field spectroscopy.
- Analytical expressions quantitatively explain experimental observations, validating the theoretical model.
