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Second-harmonic generation from electron beam deposited SiO films.
Søren Vejling Andersen1, Kjeld Pedersen
1Department of Physics and Nanotechnology at Aalborg University, Skjernvej 4a, DK-9220 Aalborg Øst, Denmark. sva@nano.aau.dk
Optics Express
|June 21, 2012
Summary
Electron-beam deposited silicon oxide (SiOx) thin films exhibit a tunable nonlinear optical response. This property, sensitive to deposition conditions and annealing, enables the creation of novel nonlinear structures for planar waveguides.
Area of Science:
- Materials Science
- Optics
- Thin Film Technology
Background:
- Nonlinear optical (NLO) materials are crucial for advanced photonic devices.
- Silicon oxide (SiOx) is a widely studied material, but its nonlinear properties are not fully exploited.
- Developing cost-effective and scalable methods for fabricating NLO SiOx films is of significant interest.
Purpose of the Study:
- To investigate the second-order nonlinear optical response of as-grown electron-beam deposited SiOx thin films.
- To understand the origin of the observed nonlinear optical properties.
- To explore the potential of these films for creating practical nonlinear optical structures.
Main Methods:
- Fabrication of SiOx thin films using electron-beam deposition on fused silica substrates.
- Characterization of nonlinear optical properties using the Maker fringes method.
- Investigation of the influence of process parameters (film thickness, annealing, charged particle trapping) on the nonlinear response.
Main Results:
- As-grown SiOx films exhibit a thickness-dependent second-order nonlinear response.
- The effective nonlinear coefficient is comparable to that of crystalline quartz.
- The nonlinear signal is highly sensitive to annealing, being completely removed after heating to a few hundred degrees Celsius.
- A retarding grid significantly reduces the nonlinear signal, suggesting a role for charged particles in the deposition process.
- The nonlinear response is attributed to the formation of oriented dipoles, likely due to negatively charged oxygen ions, leading to a non-centrosymmetric film structure.
Conclusions:
- Electron-beam deposited SiOx thin films possess a tunable second-order nonlinear optical response.
- The nonlinear properties are strongly influenced by deposition conditions and can be controlled via annealing and charged particle management.
- The ability to create well-defined nonlinear 2D structures using e-beam lithography opens avenues for fabricating nonlinear optical components for planar waveguide technology.
