定义：
脉冲时域上的最大光功率。

光脉冲的峰值功率是脉冲时域上的光功率的最大值。由于超短脉冲的脉宽可以十分窄，因此即便光束的平均功率不高，其峰值功率依旧可以十分高。例如，通过锁模激光器和再生放大器产生了一个10s的脉冲，其脉冲能量为10nJ，那么它的峰值功率则可以达到100GW的量级，相当于是一百个大型核电站的总和。如果将这一样么脉冲聚焦为一个4um大的光斑，那么其峰值光强可达4 × 1021 W/m2。通过一个较大的设备（大约一个小屋子那么大）即可以产生峰值功率达TW的激光。如果要产生峰值功率达PW的激光则需要更为复杂的具有多个啁啾脉冲放大器的设备才能时实现。 
常见的大功率单位如下： 
1kW = 103 W 
1MW = 106 W 
1GW = 109 W 
1TW = 1012 W 
1PW = 1015 W 

峰值功率的测量
对于相对较长的脉冲，其峰值功率可以利用光电二极管直接测量。对于小于几十皮秒的脉冲，这种方法不再适用。此时脉冲峰值功率通常通过脉冲脉宽τp（可以利用光学自相关仪测量）和脉冲能量Ep推算出来。这种推算有一个与脉冲的时域形状相关的系数。例如，对于孤子脉冲（双曲正割型）的峰值功率为 

对于高斯型脉冲，其常数因子约为0.94，而不是0.88。如果脉冲受到强烈的非线性脉冲畸变或类似效果的影响，其脉冲能量中的一部分会出现在它们时域的旁瓣中，此时峰值功率和脉冲能量之间的关系也将被修改。 
需要注意的是，有一些作者忽略了以上这些因素，并将脉冲能量和脉冲脉宽的简单的比率作为峰值功率。 

歧义
严格的来说，以上定义的峰值功率是不那么明确的。这取决于所述功率测量的时间分辨率（或带宽）。例如，调Q激光器常常表现出模式跳动，由于谐振腔模式跳动导致电场的振荡从而使得功率也有一个快速的振荡变化。而光电探测器则因为速度太慢而不能响应这些功率变化。

Definition: maximum optical power of a pulse

More general terms: optical power

Formula symbol: P_p

Units: W

The peak power of a light pulse is the maximum occurring optical power. Due to the short pulse durations which are possible with optical pulses, peak powers can become very high even for moderate pulse energies. For example, a pulse energy of 1 mJ in a 10-fs pulse, as can be generated with a mode-locked laser and a regenerative amplifier of moderate size, already leads to a peak power of the order of 100 GW, which is approximately the combined power of a hundred large nuclear power stations. Focusing such a pulse to a spot with e.g. 4 μm radius leads to enormous peak intensities of the order of 4 × 10²¹ W/m² = 4 × 10¹⁷ W/cm². Peak powers in the terawatt range can be generated with devices of still moderate size (fitting into a 20-m² room). Large facilities based on multi-stage chirped-pulse amplifiers can even generate pulses with petawatt peak powers.

For handling the large numbers associated with high peak powers, the following prefixes are often used:

• 1 kW (kilowatt) = 10³ W
• 1 MW (megawatt) = 10⁶ W
• 1 GW (gigawatt) = 10⁹ W
• 1 TW (terawatt) = 10¹² W
• 1 PW (petawatt) = 10¹⁵ W

Measurement of Peak Power

For relatively long pulses, the peak power can be measured directly e.g. with a photodiode which monitors the optical power versus time. For pulse durations below a few tens of picoseconds, this method is no longer viable. The peak power is then often calculated from the (full width at half-maximum, FWHM) pulse duration τ_p (measured e.g. with an optical autocorrelator) and the pulse energy E_p. The conversion depends on the temporal shape of the pulse. For example, for soliton pulses (with a sech² shape) the peak power is

For Gaussian-shaped pulses, the constant factor is ≈ 0.94 instead of 0.88. If pulses are subject to strong nonlinear pulse distortions or similar effects, a significant part of their pulse energy may be contained in their temporal wings, and the relation between peak power and pulse energy may be substantially modified.

Some authors even totally ignore such factors and present the simple ratio of pulse energy and pulse duration as the peak power.

Ambiguities

Strictly, the peak power as defined above (the maximum occurring optical power) is ambiguous; it depends on the temporal resolution (or bandwidth) of the power measurement. For example, Q-switched lasers often exhibit mode beating, i.e., an oscillation of power related to the beating of electric-field oscillations in different resonator modes. A photodetector may be too slow to resolve these power oscillations, and one may intentionally ignore such fast oscillations for the definition of peak power.