page_title: Ultrashort pulse
section_title: Definition
hierarchical_section_title: Ultrashort pulse / Definition
context_page_description: In optics, an ultrashort pulse of light is an electromagnetic pulse whose time duration is of the order of a picosecond or less. Such pulses have a broadband optical spectrum, and can be created by mode-locked oscillators. They are commonly referred to as ultrafast events. Amplification of ultrashort pulses almost always requires the technique of chirped pulse amplification, in order to avoid damage to the gain medium of the amplifier.
  They are characterized by a high peak intensity that usually leads to nonlinear interactions in various materials, including air. These processes are studied in the field of nonlinear optics.
  In the specialized literature, "ultrashort" refers to the femtosecond and picosecond range, although such pulses no longer hold the record for the shortest pulses artificially generated. Indeed, x-ray pulses with durations on the attosecond time scale have been reported.
  The 1999 Nobel Prize in Chemistry was awarded to Ahmed H. Zewail, for the use of ultrashort pulses to observe chemical reactions at the timescales on which they occur, opening up the field of femtochemistry.
context_section_description: There is no standard definition of ultrashort pulse. Usually the attribute 'ultrashort' applies to pulses with a temporal duration of a few tens of femtoseconds, but in a larger sense any pulse which lasts less than a few picoseconds can be considered ultrafast.
  A common example is a chirped Gaussian pulse, a wave whose field amplitude follows a Gaussian envelope and whose instantaneous phase has a frequency sweep.
caption: A positively chirped ultrashort pulse of light in the time domain.