Enhanced Ultrafast Nonlinear Optical Response in Ferrite Core/Shell Nanostructures with Excellent Optical Limiting...

Area of Science:

• Materials Science
• Nanotechnology
• Nonlinear Optics

Background:

• Nonlinear optical nanostructured materials are crucial for optical limiters.
• Photoinduced deterioration often reduces efficiency in existing materials.
• Robustness at high light fluences is a key challenge.

Purpose of the Study:

• To investigate the nonlinear optical properties of ferrite core/shell nanoparticles.
• To assess their suitability for ultrafast optical limiting applications.
• To understand the influence of shell thickness on optical limiting performance.

Main Methods:

• Fabrication of ferrite core/shell nanoparticles.
• Characterization of nonlinear optical properties using 100 fs ultrashort laser pulses.
• Open aperture Z-scan measurements at high intensities (up to 35 TW cm⁻²).

Main Results:

• Effective two-photon absorption (2PA) coefficient nonmonotonically depends on shell thickness, peaking for thin shells.
• Core/shell morphology enhances nonlinear optical parameters due to local electric field confinement.
• Demonstrated excellent optical limiting performance with 2PA coefficients of ~10⁻¹² cm W⁻¹ and thresholds of ~1.7 J cm⁻².
• High optical damage thresholds (up to 35 TW cm⁻²) and photostability confirmed.

Conclusions:

• Ferrite core/shell nanoparticles exhibit remarkable nonlinear optical properties and robustness.
• The core/shell design is advantageous for improving optical limiting performance.
• These nanoparticles are promising candidates for ultrafast optical limiting applications due to their high photostability and performance.