Effects of multiple internal sample reflections on nonlinear refractive Z-scan measurements

Area of Science:

• Nonlinear Optics
• Optical Metrology
• Condensed Matter Physics

Background:

• Z-scan and eclipsed Z-scan techniques are standard for measuring nonlinear optical properties.
• Internal sample reflections can introduce artifacts in these measurements.
• Understanding these reflections is crucial for accurate characterization of optical materials.

Purpose of the Study:

• To investigate the impact of multiple internal sample reflections on Z-scan and eclipsed Z-scan measurements.
• To develop a model accounting for these reflective effects.
• To analyze the resulting distortions and their implications for optical switching phenomena.

Main Methods:

• Modeling the sample as a combination of a nonlinear lens and an étalon.
• Utilizing ABCD analysis under steady-state, thin-lens, and mean-field approximations.
• Simulating beam self-focusing, self-tuning, and far-field transmittance.

Main Results:

• The model predicts nonlinear absorption effects.
• Amplification of transmittance signatures due to reflections was observed.
• Strong distortions in signatures were found in optical switching and bistability regimes.

Conclusions:

• Internal sample reflections significantly influence Z-scan measurements, leading to phenomena like nonlinear absorption and signature distortions.
• Accurate interpretation of Z-scan data requires accounting for these reflective effects.
• The findings are critical for understanding and designing optical switching and bistability devices.