Powders Analysis by Second Harmonic Generation Microscopy.

Area of Science:

• Nonlinear Optics
• Materials Science
• Crystallography

Background:

• Quantifying nonlinear optical properties of crystalline powders is crucial for materials development.
• Existing methods like Kurtz-Perry analysis have limitations in isolating optical interactions.
• Understanding the interplay between linear and nonlinear optics is key for crystal engineering.

Purpose of the Study:

• To develop a microscopy approach for quantifying second harmonic generation (SHG) activity in powders.
• To decouple linear and nonlinear optical interactions for independent evaluation.
• To enable direct comparison between experimental data and computational predictions of lattice hyperpolarizabilities.

Main Methods:

• Utilized a microscopy technique with a focused fundamental beam to control interaction length.
• Performed per-particle measurements to analyze crystal size-dependent trends.
• Developed an analytical model incorporating scattering losses of a focused Gaussian beam.

Main Results:

• The microscopy approach successfully quantified SHG activity while decoupling optical interactions.
• An analytical model accurately predicted experimental observations, including scattering length.
• Histograms of SHG intensity versus particle size and orientation matched model predictions.

Conclusions:

• The developed microscopy method offers a complementary approach to existing powder analysis techniques.
• Independent evaluation of linear and nonlinear optical effects is achievable, aiding crystal engineering.
• The approach facilitates accurate comparisons between experimental results and theoretical models for nonlinear optical materials.