Leave a message for inquiry
Leave your phone number, and we'll get in touch with you as soon as possible.
Ultra-fast Laser, ps
The picosecond pulsed laser refers to a laser with a pulse width on the picosecond scale (1 ps = 10⁻¹² seconds). It is one of the core members of the ultrafast laser family (the other being femtosecond lasers). Compared with nanosecond lasers, its pulse duration is extremely short, completing the interaction process before the material can transfer the absorbed energy as heat to the surrounding areas. This unique "cold processing" mechanism has enabled it to achieve revolutionary breakthroughs in fields such as precision machining, cutting-edge scientific research, and medical treatment.
1. The principle of picosecond laser generation
The core principle of picosecond pulse generation is mode-locking: it synchronizes the phases of all longitudinal modes (different frequency laser modes) in the laser resonator, whose coherent superposition produces a train of ultrashort, narrow pulses with minimal intervals in the time domain.
Measuring Picosecond Ultrafast Pulses
Specific Methods for Mode-Locking
1.1 Passive Mode-Locking: Typically employs saturable absorbers or leverages nonlinear effects.
(1) Saturable Absorber Mode-Locking (e.g., SESAM): Similar to passive Q-switching, but with an extremely fast recovery time, enabling pulses to form and propagate at ultra-high repetition rates (usually on the MHz scale).
(2) Kerr Lens Mode-Locking (KLM): Utilizes the Kerr effect (refractive index varies with light intensity) of gain media (e.g., titanium sapphire crystals). High-intensity light pulses induce self-focusing, forming a "virtual" aperture that results in lower loss for the pulses compared to continuous or low-intensity light, thereby achieving self-locking and compression of the pulses.
1.2 Active Mode-Locking: An external modulator (e.g., acousto-optic or electro-optic modulator) is inserted into the cavity, which modulates the laser's loss or phase at a frequency equal to the longitudinal mode spacing, forcing all longitudinal modes to synchronize. This method offers high stability but typically produces wider pulses.
Due to the extremely high peak power of picosecond pulses, direct amplification at the oscillation stage can induce nonlinear effects or even damage components. CPA (Chirped Pulse Amplification) is another cornerstone of ultrafast lasers.It involves:
(1) The seed pulse is stretched in the time domain (reducing peak power)
(2) It is safely energy-amplified via an amplifier.
(3) Compressing the amplified pulse back to its original picosecond duration.
This process results in giant pulses that possess both high energy and an ultrashort pulse width.
2. Main Classifications of Picosecond Lasers
Based on their gain media, picosecond lasers can be classified into DPSS,diode,and fiber picosecond lasers, among other types.
2.1 DPSS Picosecond Lasers
Using LD-pumped Nd:YVO₄ or Nd:YAG crystals to generate picosecond pulses via passive or active mode-locking is an earlier technical route. In recent years, disk-type picosecond solid-state lasers fabricated with gain media (e.g., thin-disk Yb:YAG crystals) have significantly improved the average power and pulse energy of lasers, making them suitable for heavy industrial processing.
2.2 Diode Picosecond Lasers
Powering the low-power didoe laser with a high-frequency pulse circuit enables picosecond laser output. This is a simple method, but limited by the rise and fall times of the pulse circuit—higher operating current of the semiconductor laser results in wider pulse widths, typically above 50–100 ps.
2.3 Fiber Picosecond Lasers (Amplifiers)
The low-power DPSS picosecond laser or diode picosecond laser is used as the seed source, with high power or high energy output achieved with a fiber amplifier. Fiber picosecond lasers (amplifiers) feature excellent beam quality (M² close to 1), superior heat dissipation, compact structure, high stability, and simple maintenance, making them the mainstream picosecond lasers in current industrial applications.
2.4 Ti:Sapphire Picosecond Lasers
The gain medium uses a titanium sapphire crystal, which features a wide tuning range (~680–1100 nm) and is a powerful tool for scientific research. However, it needs another laser (e.g., a green laser) as the pump source, resulting in a complex system and high cost. CNI offers ideal 532 nm single-frequency lasers and ultra-low noise laser sources (model: MLL-K-532) for titanium sapphire pumping.
3. Applications of Picosecond Lasers
The "cold processing" characteristic (or "cold ablation") of picosecond lasers is the foundation for all their high-end applications. Since the interaction time is much shorter than the electron-lattice thermal relaxation time (~1–10 ps), energy barely has time to diffuse as heat. Materials are directly ionized and vaporized, resulting in a negligible heat-affected zone (HAZ).
3.1 Ultra-High Precision Industrial Micromachining
This is the largest application market for picosecond lasers, especially in the consumer electronics sector.
(1) Precision Machining of Brittle Materials: OLED/flexible displays, glass/sapphire cutting, semiconductor wafer dicing, etc.
(2) Thin-Film Processing and Stripping: Passivation layer grooving of PERC cells in the photovoltaic industry, precise stripping of transparent conductive films such as ITO, etc.
(3) Surface Microstructure Fabrication: Production of anti-counterfeiting patterns, anti-reflective microstructures, hydrophobic surfaces, etc.
(4) Micro-Drilling: Drilling micron-scale holes in products such as fuel injectors and medical catheters.
3.2 Medical and Aesthetic Applications
(1) Femtosecond laser surgery (LASIK flap creation), cataract surgery
(2) Cosmetic spot removal
3.3 Frontier Scientific Research
Picosecond lasers are the "high-speed cameras" for exploring ultrafast processes.
(1) Ultrafast Spectroscopy: Used to study ultrafast microscopic processes occurring on the picosecond to femtosecond scale, such as chemical reaction kinetics, photosynthesis processes, and carrier relaxation in quantum materials.
(2) Multiphoton Microscopy: Picosecond lasers can serve as excitation light sources to achieve high-resolution, deep-tissue imaging of living biological samples without sectioning or staining.
(3) High-Harmonic Generation (HHG) & Attosecond Pulse Generation: Used to produce extreme ultraviolet (EUV) light sources and attosecond pulses, serving as tools for probing ultrafast electron dynamics within atoms.
4. Typical Picosecond Lasers
CNI offers DPSS,diode,and fiber picosecond lasers with pulse widths ranging from 1 to 1000 ps. The typical wavelengths cover ultraviolet (213, 266, 280, 295, 310, 343, 355, 375 nm), visible (405, 450, 488, 515, 532, 540, 560, 590, 620, 633, 660 nm), infrared (775, 852, 1030, 1050, 1064, 1070, 1080, 1550 nm), and tunable wavelengths (470–2400 nm), etc. For more information, please visit www.cnilaser.com/.
Fiber Picosecond Lasers | DPSS Picosecond Lasers | Diode Picosecond Lasers |
Picosecond ultrafast lasers are the future of precision machining. Their unmatched cold processing advantages solve nanosecond lasers’ bottlenecks in HAZ, precision, and material compatibility, enabling "scalpel-like" micrometer/nanometer-scale processing. Despite higher costs, their value in boosting performance, yield, and reliability in high-value-added industries drives rapid adoption from labs to large-scale production lines.
Changchun New Industries Optoelectronics Technology Co., Ltd.
Address: No. 888 Jinhu Road, High-Tech Zone, Changchun, 130103, P.R.China
International Tel:+86-431-85603799
Email: sales@cnilaser.com
Send a Message
Leave your phone number, and we'll get in touch with you as soon as possible.