The Thermo-Optic Effect in Norbixin: Characterization by Z‑Scan and Self-Phase Modulation under CW Laser

Area of Science:

• Nonlinear Optics
• Materials Science
• Photonic Applications

Background:

• Norbixin is a natural dye derived from Bixa orellana seeds.
• Understanding its nonlinear optical properties is crucial for developing new photonic materials.

Purpose of the Study:

• To investigate the thermal nonlinear optical properties of norbixin in acetone.
• To characterize its optical response and nonlinear behavior under laser illumination.

Main Methods:

• UV-vis, FT-IR, and Raman spectroscopies for characterization.
• Z-scan technique and far-field diffraction pattern analysis for nonlinear optical properties.
• Tauc plot method for optical band gap estimation.

Main Results:

• Estimated optical band gap of 2.40 eV, indicating near-resonant excitation.
• Observed saturable absorption (SA) with β = -1.27 × 10⁻⁴ cm²/W.
• Determined negative nonlinear refractive index (n₂,th) of -5.28 × 10⁻⁹ cm²/W due to self-defocusing.
• Noted a discrepancy in nonlinear parameters between Z-scan and SSPM, attributed to thermal effects and convection.

Conclusions:

• Norbixin demonstrates significant potential as a sustainable nonlinear optical material.
• Results provide fundamental insights into thermo-optic effects and convection in nonlinear media.
• Norbixin is suitable for applications like optical limiters and all-optical switches.