Čerenkov-type second-harmonic spectroscopy in random nonlinear photonic structures.

Area of Science:

• Nonlinear optics
• Materials science
• Photonics

Background:

• Čerenkov-type second-harmonic generation (CSHG) is a nonlinear optical process.
• Ferroelectric domain structures influence nonlinear optical properties.
• Characterizing domain structures is crucial for photonic device applications.

Purpose of the Study:

• To investigate CSHG in random nonlinear photonic structures with varying 2D ferroelectric domain distributions.
• To develop and validate a spectroscopic method for estimating average ferroelectric domain size.
• To retrieve domain patterns using experimental and theoretical analyses.

Main Methods:

• Experimental measurements of CSHG signals varying incidence angles and fundamental wave polarizations.
• Analysis of spatial Fourier spectra of domain patterns derived from CSHG signals.
• Numerical simulations of Fourier spectra for comparison with experimental data.
• CSHG microscopy for direct visualization and comparison of domain patterns.

Main Results:

• Čerenkov-type second-harmonic generation spectroscopy effectively estimates average ferroelectric domain size.
• Retrieved domain patterns from spectroscopic analysis show good agreement with CSHG microscopy.
• The study demonstrates the capability of CSHG spectroscopy to probe microstructural features.

Conclusions:

• CSHG spectroscopy is a viable tool for characterizing ferroelectric domain structures in nonlinear photonic materials.
• The findings contribute to understanding light-matter interactions in disordered nonlinear media.
• This method offers a complementary approach to traditional domain imaging techniques.