3D nanopolymerization and damage threshold dependence on laser wavelength and pulse duration

Area of Science:

• Materials Science
• Optical Engineering
• Polymer Chemistry

Background:

• Multi-photon polymerization (MPP) lithography is a key technique for 3D microfabrication.
• Understanding polymerization and optical damage thresholds is crucial for precise control in MPP.
• The influence of laser parameters like wavelength and pulse duration on MPP processes requires further investigation.

Purpose of the Study:

• To investigate the dependence of polymerization and optical damage thresholds in MPP lithography.
• To explore the impact of wavelength and pulse duration on light-matter interactions and fabrication windows.
• To optimize energy delivery for advanced MPP applications.

Main Methods:

• Utilized a broadly-tunable laser system with group delay dispersion (GDD) control.
• Employed the resolution bridges method to study non-linearity and light-matter interactions.
• Measured energy deposition, voxel growth, and dynamic fabrication window (DFW) across 700-1300 nm wavelengths and 100-300 fs pulse durations.

Main Results:

• Polymerization occurred across all tested wavelengths and pulse durations, achieving consistent minimal spatial dimensions.
• An abrupt change in polymerization power dependence and significant DFW variation (1 to 29) were observed with changing wavelength.
• Results suggest a shift in instantaneous refractive index and altered polymerization/damage thresholds at different wavelengths.

Conclusions:

• Wavelength tuning and pulse duration control are critical for optimizing energy delivery in MPP.
• The study reveals the complex interplay of factors governing polymerization and damage thresholds in MPP.
• Findings provide valuable insights for the advancement of MPP lithography technology.