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Observing the interplay between surface and bulk optical nonlinearities in thin van der Waals crystals
Skylar Deckoff-Jones1, Jingjing Zhang1, Christopher E Petoukhoff1
1Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Japan.
Scientific Reports
|March 4, 2016
Summary
Researchers observed an unexpected peak in second harmonic generation in Indium Selenide crystals. This phenomenon arises from interference between surface and bulk nonlinearities, offering new ways to engineer optical properties.
Area of Science:
- Condensed matter physics
- Materials science
- Nonlinear optics
Background:
- Van der Waals materials exhibit thickness-dependent nonlinear optical properties.
- Surface and bulk nonlinearities typically dominate at extreme thinness or bulk limits, respectively.
- Understanding this interplay is crucial for advanced optical applications.
Purpose of the Study:
- To investigate the thickness-dependent nonlinear optical response of Indium Selenide (InSe) crystals.
- To explain the observed deviation from expected quadratic intensity increase with thickness.
- To explore interference effects between surface and bulk nonlinearities.
Main Methods:
- Fabrication of Indium Selenide crystals with varying thicknesses.
- Measurement of generated second harmonic (SH) signal intensity as a function of crystal thickness.
- Theoretical modeling to explain the observed SH signal behavior.
Main Results:
- An unexpected peak in the generated second harmonic signal intensity was observed with increasing crystal thickness.
- The results contradict the typically expected quadratic increase in SH signal for thin nonlinear crystals.
- Interference between surface and bulk nonlinear optical responses was identified as the cause.
Conclusions:
- Interference effects between surface and bulk nonlinearities provide a novel mechanism to control nonlinear optical responses.
- This finding offers new strategies for engineering the optical properties of 2D materials and heterostructures.
- The study highlights the importance of considering interference in layered materials for optical applications.
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