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Updated: Feb 19, 2026
15:06
Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle
Published on: January 3, 2016
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Recognition of multipolar second-order nonlinearities in thin-film samples
Optics Express
|November 3, 2017
Summary
Second-harmonic generation in silicon nitride (SiN) films shows strong multipolar signals. However, these signals are fully explained by the material's dipolar response when internal reflections are considered.
Area of Science:
- Nonlinear optics
- Materials science
- Photonics
Background:
- Second-harmonic generation (SHG) is a key nonlinear optical process.
- Distinguishing between dipolar and multipolar nonlinear contributions is crucial for accurate material characterization.
- Silicon nitride (SiN) thin films are widely used in optical applications.
Purpose of the Study:
- To investigate the nonlinear optical properties of silicon nitride (SiN) thin films using two-beam second-harmonic generation.
- To differentiate between dipolar and higher-multipolar contributions to the nonlinear response in SiN films.
- To assess the influence of multiple reflections on SHG measurements in thin films.
Main Methods:
- Utilized two-beam second-harmonic generation (SHG) spectroscopy.
- Analyzed thin films of silicon nitride (SiN).
- Modeled nonlinear contributions, considering multiple reflections of fundamental and second-harmonic waves.
Main Results:
- Observed strong apparent multipolar signatures in the SHG response of SiN films.
- Demonstrated that these signatures can be fully accounted for by the dipolar nonlinearity.
- Highlighted the critical role of multiple internal reflections in interpreting SHG data from thin films.
Conclusions:
- The apparent multipolar nonlinearities in SiN thin films are an artifact of multiple reflections.
- Accurate characterization of nonlinear optical properties in thin films requires careful consideration of optical interference effects.
- Standard SHG techniques may misinterpret intrinsic material properties in thin film samples without accounting for multiple reflections.
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