Micro-Nano Processing: Femtosecond Laser vs. Picosecond Laser – How to Choose Tool?

In high-precision fields such as microelectronic manufacturing, medical device R&D, and optical component processing, "non-contact processing" has become a core requirement for ensuring product quality. As two major tools in the ultrafast laser family, femtosecond lasers and picosecond lasers often leave customers in a dilemma. Today, we will clarify the ideas for you from definitions, processing effects to selection logic.  

What Are the Core Differences Between Femtosecond and Picosecond Lasers?

Femtosecond lasers and picosecond lasers are named after their pulse durations.  

From the "Time" Definition

The "pulse duration" of a laser directly determines the efficiency of energy transfer to materials.  

• Picosecond laser (ps): Pulse duration is approximately 10⁻¹² seconds (one trillionth of a second).  

• Femtosecond laser (fs): Pulse duration is as low as 10⁻¹⁵ seconds (one quadrillionth of a second), which is 1/1000 of a picosecond. If a picosecond is an "instant," a femtosecond is "the instant within an instant."  

Te more intuitive time conversion below helps you quickly understand the "ultrafast" scale:  

1 second = 10³ milliseconds = 10⁶ microseconds = 10⁹ nanoseconds = 10¹² picoseconds = 10¹⁵ femtoseconds = 10¹⁸ attoseconds (as)  

Among them, attosecond lasers: Their pulse duration is shorter (10⁻¹⁸ seconds), theoretically capable of capturing atomic-level ultrafast processes. However, they are still in the laboratory research stage and have not yet achieved industrial application. Femtosecond and picosecond lasers, on the other hand, have mature commercial applications and are the mainstream choices for current micro-nano processing.  

Processing Effects

Differences in pulse duration directly affect their peak power characteristics. Imagine laser energy as a "shock wave" – the shorter the action time, the more concentrated the energy, and the "cleaner" the material removal. Under the same pulse energy and wavelength, femtosecond lasers can achieve finer spot focusing to meet sub-micron processing requirements.  

Three Typical Scenarios: Who Performs Better?

Can it solve my processing needs? Let’s look at the performance of the two in the three most common micro-nano processing scenarios: drilling, cutting, and etching.  

Drilling

Drilling is a core process for electronic components (such as ceramic substrates, silicon wafers) and medical devices (such as stent microholes). The key requirements are "smooth hole walls, no slag, and uniform hole diameter."  

SEM images of holes drilled on 500μm-thick silicon wafers by femtosecond laser pulses (left) and picosecond laser pulses (right). Total processing time for both cases is 25 seconds.  

Femtosecond Laser: The "Benchmark" for High-Precision Microholes

The "ultra-short time" of femtosecond pulses prevents materials from thermal diffusion – energy directly sublimates materials from solid to gas (i.e., "cold processing"). After processing, the hole walls are smooth, almost free of any slag, and the hole diameter is uniform. It is especially suitable for high-precision scenarios such as semiconductor microholes, medical tools (requiring no burrs to avoid tissue damage), and optical components (high-transmittance microholes).  

Picosecond Laser: The "Efficient Choice" for Medium-Precision Scenarios

Picosecond lasers have faster processing speeds. However, picosecond lasers have thermal impact – when processing deep holes or thick materials, the hole walls are prone to molten layers, requiring additional "polishing steps." They are suitable for mass-production scenarios with slightly higher tolerance for slag.  

Cutting

The core contradiction of cutting is the balance between "speed" and "edge quality," and material properties directly determine which laser is more suitable:  

Metal Cutting: Picosecond for Speed, Femtosecond for Precision

Metals have fast thermal conductivity (the diffusion time of the heated area is about 1ps). Both femtosecond and picosecond lasers can avoid the "thermal deformation" problem of traditional lasers, but the differences are still obvious:  

• Picosecond laser: With high repetition rate, it is faster than femtosecond when cutting thin metals (such as 100μm steel foil), and the edge quality can meet most industrial needs. It is an ideal choice for mass production of metal sheets.  

• Femtosecond laser: Can deliver "zero thermal deformation" smooth cuts (Ra < 0.1μm), suitable for aerospace parts and high-end medical surgical tools that require strict edge quality.  

Cutting quality comparison between femtosecond laser pulses (left) and picosecond laser pulses (right) – picosecond laser causes edge discoloration.  

Heat-Sensitive/Transparent Material Cutting: Femtosecond is the "Only Solution"

For heat-sensitive materials such as plastic films and polymers, the slight thermal accumulation of picosecond lasers can cause deformation and carbonization due to thermal load.  

Femtosecond laser’s "cold processing" can perfectly avoid these problems, achieving crack-free and debris-free edges. It has become an ideal tool for microfluidic chip processing. 

Etching

Etching (especially microstructural etching) has stricter requirements for "thermal impact zone" and "dimensional accuracy," and the advantages of femtosecond lasers will be infinitely amplified at this time:  

Fig.1. A schematic illustration of Al surface ablation using (a) fs and (b) ps laser pulses and formation of microgroove.)    

• Femtosecond laser: With a near-zero thermal impact zone (<1μm), it can accurately engrave depth-controllable microstructures on semiconductor materials without damaging the underlying material – this is crucial for cutting-edge applications such as MEMS (Micro-Electro-Mechanical Systems) devices.  

Picosecond laser: Although it can also perform surface etching, heat accumulation is likely to cause "collapse" of the edges of fine structures. It is more suitable for processing various microstructures with slightly lower precision and larger format.  

Microtexture etching of contact lenses transfer plates – femtosecond laser (left) produces cleaner edges and higher finish than picosecond laser (right).

Summary: 3 Steps to Select the Right Laser Equipment

The choice between picosecond and femtosecond laser equipment depends on specific application needs, precision requirements, efficiency goals, and budget constraints. 3 steps to help you evaluate:  

Step 1: Check the Material – Prioritize Femtosecond for Heat-Sensitive/Transparent/Super-Hard Materials

• If the processing object is polymer, ceramic, or transparent material, femtosecond laser’s ultra-short pulses can avoid cracking and slag caused by thermal impact. It can also achieve 3D micro-nano processing inside transparent materials through multiphoton absorption, making it a more reliable choice.  

• If it is thin metal with slightly higher tolerance for thermal impact, picosecond laser is more efficient.  

Step 2: Check the Precision – Femtosecond is a Must for Sub-Micron/High Aspect Ratio Holes/3D Etching

• If the requirements for precision and thermal impact zone are extremely high (e.g., precision drilling of special-shaped holes, sub-micron level (<1μm), near-zero thermal impact zone), femtosecond laser can achieve finer details.  

Step 3: Check the Scenario – Choose Femtosecond for R&D/High-End Industry

• R&D field: Whether it is optical waveguide direct writing, MEMS device R&D, or application research of new materials, the high precision and flexibility of femtosecond lasers are their core advantages.  

• Industrial field: For mass cutting of thin metal parts and array drilling, picosecond laser equipment provides faster processing speed and higher cost-effectiveness for applications with low precision requirements. If producing semiconductor components, high-end medical devices, or optical components, the "damage-free" processing of femtosecond lasers can enhance product competitiveness, making it more worthwhile for long-term investment.  

Conclusion

There is no "absolutely better" tool, only a "more suitable" choice. If your project needs to achieve extremely high-quality micro-details, femtosecond laser is the best choice. If you want to achieve high precision while ensuring speed and cost, picosecond laser is the ideal option.  

The integration of ultrafast laser equipment is very complex, involving multiple components, each of which must be carefully designed to maintain the precision performance of the equipment. As an enterprise specializing in femtosecond laser technology, MONO provides a series of femtosecond laser equipment to meet the needs of stable industrial mass production and scientific research and development. If you have more questions, please feel free to contact us for a customized solution for your products.