定义：
输出脉冲脉宽为皮秒量级的激光器。

皮秒激光器通产指的是发射的脉冲的脉宽为1ps到几十ps的激光器。它属于超快激光器或超短脉冲激光器。 
有多种类型的激光器可以产生皮秒脉冲： 

1. 最常见的是主动或被动锁模的固体激光器。这些激光器可以提供非常高质量（变换极限且低噪音）的超短脉冲，其脉冲重复频率通产在几MHz到100GHz之间。例如，一个被动锁模的Nd：YAG或钒酸盐激光器可以容易地产生如10-ps的具有数瓦功率的脉冲，而薄型激光器则可以产生更短的具有几十瓦平均功率的脉冲。 
2. 锁模光纤激光器也可以输出皮秒激光，其重复频率可以从几MHz到100GHz（谐波锁模）之间。当利用主振荡光纤放大器结构是，其输出的平均功率将会是非常高的。锁模光纤激光器输出的脉冲质量差别很大，例如，其脉冲可能是也可能不是带宽极限脉冲。 
3. 更低重复频率的激光器则可以通过附加脉冲选择器（pulse picker）实现。这种激光器可以再生放大器进行啁啾脉冲放大，从而获得更高脉冲能量的激光。具有倾斜腔的锁模激光器则是另一种可行选择。 
4. 激光二极管的锁模可以产生皮秒脉冲（参阅锁模二极管激光器）。这可以实现非常紧凑且低成本的皮秒脉冲源，其重复频率通常在1GHz到100GHz之间。但是这种脉冲的脉冲能量受到严格的限制，且脉冲质量并不是很高。 
5. 利用精心设计的电学装置对激光二极管进行增益开关也可以实现脉宽低于1ns的脉冲，有时其脉宽甚至可以小于100ps。通过这种方法可以实现非常紧凑且廉价的光源，这种方法的另一个优点是可以通过电学装置可以很容易的使得脉冲的重复频率在很宽的范围内发生变化。 
6. 调Q激光器通常会产生纳秒脉冲，但是调Q的微片激光器可以产生脉宽低于100 ps的脉冲。 
7. 皮秒脉冲的一种奇特来源是自由电子激光器，它甚至可以在特殊的波长区域提供高脉冲能量的皮秒脉冲。 

与飞秒激光器相比，皮秒激光光源通常更为经济实惠。在应用中，如微加工中，皮秒激光器的性能与飞秒激光器相当。
 

Definition: lasers emitting pulses with picosecond durations

Alternative term: ultrafast lasers

More general terms: pulsed lasers, mode-locked lasers

A picosecond laser is a laser which emits optical pulses with a duration between 1 ps and (usually) some tens of picoseconds. It thus also belongs to the category of ultrafast lasers or ultrashort pulse lasers.

Sometimes, other laser-based sources for picosecond pulses – for example synchronously pumped OPOs – are also called picosecond lasers, even if they are strictly speaking no lasers.

A variety of laser types can generate picosecond pulses, with other performance parameters varying in wide ranges:

• The most common sources are actively or passively mode-locked solid-state bulk lasers. These can provide very clean (transform-limited and low-noise) ultrashort pulses with pulse repetition rates varying from a few megahertz to more than 100 GHz. For example, a passively mode-locked Nd:YAG or vanadate laser can easily generate e.g. 10-ps pulses with several watts of output power, and thin-disk lasers can generate many tens of watts in shorter pulses.
• Mode-locked fiber lasers can also cover a wide range of repetition rates from a few megahertz up to more than 100 GHz (with harmonic mode locking). Particularly with MOPA or MOFA systems, very high average output powers are possible. The pulse quality from such sources varies; for example, the pulses may or may not be close to bandwidth-limited.
• Lower repetition rates are possible with an additional pulse picker and also allow for amplification to higher pulse energies e.g. with a regenerative amplifier, possibly using chirped-pulse amplification. Cavity dumping of a mode-locked laser is another option.
• Laser diodes can be mode-locked for picosecond pulse generation (→ mode-locked diode lasers). This leads to compact sources with typical pulse repetition rates between 1 GHz and hundreds of gigahertz. However, the pulse energy is severely limited, and the pulse quality is not always high.
• Laser diodes can also be gain-switched with carefully designed electronics to achieve pulse durations of well below 1 ns, sometimes even below 100 ps. This leads to very compact and potentially cheap sources, and another advantage is that the pulse repetition rate can easily be varied in a very wide range simply via the driver electronics. See the article on picosecond diode lasers.
• Although Q-switched lasers typically generate nanosecond pulses, Q-switched microchip lasers can reach pulse durations far below 100 ps.
• More exotic sources of picosecond pulses are free electron lasers, which can provide high pulse energies even in extreme wavelength regions.

Applications of Picosecond Lasers

Picosecond lasers are used in a wide range of laser applications. Some of these lasers are industrial lasers, while others are scientific lasers. Some typical applications are discussed in the following.

Laser Material Processing

In laser material processing, e.g. laser drilling or cutting, it is often advantageous to use very short light pulses having correspondingly high peak powers for a given pulse energy. Nanosecond pulse durations (from nanosecond lasers) are often too long, because a substantial spread of deposited energy can occur by thermal conduction during the pulse duration. This is quite different for pulse durations of e.g. 10 ps or less, where there is minimum heat diffusion during the pulse duration. As a result, substantially finer structures can be processed with high quality (laser micromachining). Note, however, that high quality results usually require a careful optimization of many process details.

Compared with femtosecond lasers, picosecond laser sources are often more economical: a higher average output power is available at a lower price. In applications such as laser micromachining, one sometimes achieves better quality results with femtosecond pulses, but picosecond pulses are often sufficient when the process is sufficiently optimized overall. In such cases, picosecond lasers are often preferred.

Medical Applications

There are some medical applications where picosecond pulses have advantages. A common application is the removal of tattoos, and similarly one may reduce pigments of natural origins. There are also surgical procedures where precise material ablation can be achieved with picosecond pulses.

Laser Microscopy

Some laser microscopes are operated with picosecond pulses, although femtosecond pulses have substantial advantages in some cases.

OPO Pumping

Many synchronously pumped optical parametric oscillators are pumped with picosecond lasers. Sometimes, the whole setup is still called a picosecond laser, even though it also contains an OPO.

Measurements

Picosecond laser pulses are useful for a very wide range of measurements. For example, distance measurements with LIDAR, e.g. based on time-of-flight measurements, can be performed. Picosecond pulses are also often used in pump–probe measurements on timescales of multiple picoseconds to nanoseconds.

Telecommunications

In the area of optical fiber communications, picosecond lasers can be used in different ways. For example, picosecond lasers may be used for generating soliton pulses in optical fibers, which propagate without dispersive broadening. For such purposes, compact and cheap lasers with gigahertz repetition rates, often with emission in the 1.5-μm telecom bands, are required.