Optical limiting properties of surface functionalized nanodiamonds probed by the Z-scan method

Area of Science:

• Materials Science
• Nanotechnology
• Nonlinear Optics

Background:

• Optical limiting materials are crucial for protecting sensitive optical equipment.
• Surface modification of nanodiamonds (DNDs) can tune their nonlinear optical properties.
• Understanding the influence of surface termination on DND optical limiting is essential.

Purpose of the Study:

• To investigate and compare the optical limiting behavior of surface-modified nanodiamonds (DND-NH2 and DND-H) with unfunctionalized DNDs.
• To characterize their nonlinear optical properties using various techniques.
• To elucidate the mechanisms behind their optical limiting performance.

Main Methods:

• Nonlinear transmittance measurements.
• Z-scan experiments to determine nonlinear refraction and absorption.
• Scattered intensity assessments using a nanosecond pulsed Nd:YAG laser (532 nm).

Main Results:

• DND-H demonstrated the largest nonlinear attenuation.
• DND-H and DND-NH2 exhibited low optical limiting thresholds attributed to negative electron affinity (NEA).
• DND-H showed combined nonlinear refraction and absorption; DNDs suggested thermal origin; DND-NH2 displayed an unexpected positive nonlinear refraction coefficient.

Conclusions:

• Surface modification significantly impacts the optical limiting performance of nanodiamonds.
• DND-H and DND-NH2 are promising candidates for optical limiting applications due to their NEA character.
• Further research into the nonlinear optical mechanisms of functionalized nanodiamonds is warranted.