At the moment when femtosecond laser breaks the diameter of a hair, it has completed thousands of cycles. This ultra fast and precise characteristic is reshaping the boundaries of modern manufacturing. As a cutting-edge technology in the field of precision manufacturing, ultrafast laser processing technology has become a tool for micro nano scale machining due to its unique characteristics of ultra short pulses and ultra-high peak power. From the irregular cutting of smartphone screens to the precise processing of heart stents, from aerospace material processing to medical equipment manufacturing, ultrafast lasers are breaking through the limitations of traditional manufacturing with their "cold processing" advantages.

01 Physical Characteristics and Core Principles of Ultrafast Laser

Ultrafast lasers typically refer to laser pulses with pulse widths ranging from picoseconds to femtoseconds. One picosecond is equal to one billionth of a second, and one femtosecond is even one thousandth of a picosecond. Within 1 picosecond, light can only propagate about 0.3 millimeters, which is equivalent to the diameter of a human hair. The core value of ultrafast lasers lies in their unique mechanism of interaction with materials. When the laser pulse width reaches the picosecond or femtosecond level, the laser energy will be injected into the material in a very short period of time, causing the material to rapidly vaporize and avoiding thermal diffusion effects, achieving the so-called "cold processing". Unlike traditional long pulse lasers, during ultrafast laser processing, the material does not have enough time to melt and diffuse into the surrounding material within the focused volume after being heated. Femtosecond laser can induce rapid ionization of materials, directly converting the irradiated area into a mixture of plasma, steam, and nanodroplets before spraying them out. The material melting and thermal diffusion generated during the processing can be ignored. For transparent materials, ultrafast lasers achieve internal processing through nonlinear multiphoton absorption. When photons of density are incident on a material, even if the energy of a single photon is less than the bandgap of the material, an electron can be excited by multiple photons absorbed simultaneously. This nonlinear absorption usually only occurs near the laser focus, allowing ultrafast lasers to achieve three-dimensional processing inside transparent materials.

02 Key technological breakthroughs and processing methods

The main technical means of ultrafast laser processing include femtosecond laser direct writing and femtosecond laser parallel processing. Femtosecond laser direct writing technology does not require a mask and achieves two-dimensional or three-dimensional molding processing by controlling the beam scanning, with processing resolution reaching the nanometer level. Pulse train technology is an important innovation in recent years. Ultra fast lasers have also developed special processing technologies such as invisible cutting, laser-induced forward transfer, and micro welding. Taking smartphone screen cutting as an example, ultrafast laser can induce tiny cracks inside transparent materials, achieving precise cutting of any shape and meeting the processing needs of various forms such as full screen, notch screen, water droplet screen, etc.

03 Application Fields and Industrialization Value

In the field of electronic manufacturing, ultrafast lasers have become a key tool for cutting full screen mobile phones. Medical equipment manufacturing is another important application area of ultrafast lasers. In the processing of heart stents, traditional lasers have problems such as burrs and uneven groove widths, while femtosecond laser processed heart stents have a smooth surface, greatly reducing the opportunity for scar tissue growth and improving biocompatibility. In the aerospace field, ultrafast lasers have solved the processing problems of difficult to machine materials such as high-temperature alloys and thermal barrier ceramics. For example, the two-step spiral drilling method using femtosecond laser can achieve high-quality machining of air film holes in aircraft engine blades, without defects such as splashing, microcracks, and heat affected zones. The semiconductor industry also benefits from ultrafast laser technology.

04 Development Trends and Future Prospects

With the cost reduction and improvement of intelligence level of ultrafast lasers, this technology, which was once only used in the field, is gradually moving towards wider industrial applications, providing core driving force for the transformation and upgrading of the manufacturing industry. From laboratory to industrialization, ultrafast laser processing technology only took a short twenty years. It has replaced traditional mechanical cutting tools and become a "precision surgical knife" for manufacturing, constantly improving machining accuracy and efficiency boundaries. In the future, with the maturity and industrialization of attosecond laser technology, ultrafast laser processing will also demonstrate its uniqueness in more fields such as quantum communication and biomedicine.