Usable Analytical Expressions for Temperature Distribution Induced by Ultrafast Laser Pulses in Dielectric Solids

Area of Science:

• Materials Science
• Laser Physics
• Thermodynamics

Background:

• Temperature changes are critical drivers for material transformations in ultrafast direct laser writing.
• Controlling temporal dynamics and spatial temperature distribution is essential for precise material modification.

Purpose of the Study:

• To develop easy-to-use analytical expressions for temperature variations in ultrafast direct laser writing.
• To facilitate engineering tasks and provide insights into heat accumulation and material modification processes.

Main Methods:

• Derivation of analytical expressions for temperature variations induced by multi-pulse absorption for sub-nanosecond pulses.
• Analysis of temperature dynamics considering spherical energy sources and dependence on initial temperature and pulse period to diffusion time ratio.
• Calculation of the minimum number of pulses required to reach a steady-state temperature.

Main Results:

• Temperature variations depend on initial center temperature (T00) and a factor R (pulse period/diffusion time ratio).
• Steady-state temperature is reached, and heat accumulation is precisely defined, not always correlating with temperature increase.
• Temporal temperature differences between focal and non-focal areas are highlighted, with potential for simplified averaging.

Conclusions:

• The developed expressions simplify the understanding and control of temperature effects in direct laser writing.
• This work aids in determining the role of temperature in laser-induced material modifications and experimental setup design.
• Provides a foundation for comprehending diverse experimental observations and applications in ultrafast laser processing.