Differences Between Femtosecond Lasers and Picosecond Lasers

Femtosecond laser systems and picosecond laser systems are ultrashort-pulse laser devices used in precision machining, medical treatment, and scientific research. Their pulse widths differ by several orders of magnitude, which leads to significant differences in the interaction mechanisms between light and materials. As a result, they show different characteristics in machining quality, thermal-effect control, and material compatibility.

1. Pulse Width Comparison

Femtosecond laser pulse width: on the order of 10⁻¹⁵ s

Picosecond laser pulse width: on the order of 10⁻¹² s

The shorter the pulse width, the shorter the energy deposition time in the material, preventing significant thermal diffusion and forming a “cold-processing” characteristic. Femtosecond lasers offer higher peak power density and a lower thermal-affected zone within the ultrashort-pulse range.

2. Light–Material Interaction Mechanism
2.1 Picosecond Lasers

Picosecond pulses can achieve high-peak-power photoionization. Through multiphoton absorption and nonlinear effects, the material undergoes rapid melting and vaporization. A certain thermal-affected zone still exists during machining. Picosecond lasers are suitable for micro-machining of metals, ceramics, and glass.

2.2 Femtosecond Lasers

Femtosecond pulses provide higher peak power and can complete electron excitation and bond breaking within an extremely short time, forming a non-thermal ablation mechanism. There is almost no molten layer and minimal debris, making them suitable for thermally sensitive materials or high-precision structures that require low-damage machining.

3. Application Fields
3.1 Picosecond Laser Applications

Metal micro-engraving

Glass drilling and surface scribing

PCB marking and micro-hole machining

Phone-housing surface texturing and gentle cleaning

Medical dermatology equipment

Picosecond lasers offer stability in industrial production environments and are suitable for medium-to-high precision machining tasks.

3.2 Femtosecond Laser Applications

Precision optical-glass internal engraving and material modification

Semiconductor wafer dicing and low-damage cutting

Ophthalmic corneal surgery

Low-thermal-damage machining of polymers and brittle materials

Femtosecond lasers are suited for high-end manufacturing and scientific research and require higher environmental stability.

4. Process Differences

Picosecond processing: Material exhibits micro-melting with slight recast layers, often requiring post-processing; suitable for medium-speed, medium-precision tasks.

Femtosecond processing: Material is directly ionized and removed without melting or carbonization, producing smooth edges; suitable for high-precision and ultra-microstructure fabrication.

5. Equipment Selection Principles

Cost-driven requirements: choose picosecond lasers.

High-precision and minimal thermal-effect requirements: choose femtosecond lasers.

Micro-fabrication of glass, wafers, and polymers: prefer femtosecond lasers.

Metal engraving, marking, and micro-hole machining: picosecond lasers offer better cost-performance.

Femtosecond lasers provide shorter pulse duration and higher peak power than picosecond lasers, enabling near-zero thermal-effect processing. Picosecond lasers offer advantages in cost, stability, and general-purpose machining capabilities. Users should select the appropriate ultrashort-pulse laser equipment based on process requirements, precision level, material characteristics, and budget.