Chirped pulse amplification (CPA) or optical parametric chirped pulse amplification, is a technique for amplifying an ultrashort laser pulse up to the petawatt level with the laser pulse being stretched out temporally and spectrally prior to amplification. CPA is the current state of the art technique which all of the highest power (greater than about 500 terawatts) lasers in the world currently utilize. Some examples of these lasers are the Vulcan Petawatt Upgrade at the Rutherford Appleton Laboratory's central laser facility, the Gekko Petawatt laser at the Gekko XII facility in the Institute of Laser Engineering at Osaka University, the soon to be completed OMEGA EP laser at the University of Rochester's Lab for Laser Energetics and the now dismantled petawatt line on the former Nova Laser at the Lawrence Livermore National Laboratory. Introduction In optics, an ultrashort pulse of light is an electromagnetic pulse whose time duration is on the order of the femtosecond ( second). ... Lasers range in size from microscopic diode lasers (top) with numerous applications, to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion, nuclear weapons research and other high energy density physics experiments. ... This page lists examples of the power in watts produced by various different sources of energy. ... This page lists examples of the power in watts produced by various different sources of energy. ... Aerial View of Rutherford Appleton Lab The Rutherford Appleton Laboratory (RAL) at the Chilton/Harwell Science Campus is a UK scientific research laboratory near Didcot in Oxfordshire. ... Osaka University (大阪大学 Ōsaka Daigaku; abbreviated to 阪大 Handai) is a public coeducational research university in Suita, Osaka, Japan. ... The Laboratory for Laser Energetics (LLE) is a scientific research facility which is part of the University of Rochesters south campus, located in Rochester, New York. ... The Nova laser was a laser built at the Lawrence Livermore National Laboratory in 1984 and which conducted advanced inertial confinement fusion experiments until its dismantling in 1999. ... Aerial view of the lab and surrounding area. ...

CPA was invented by Gérard Mourou at the University of Rochester in the mid 1980s. Before then, the peak power of laser pulses was limited due to the fact that a laser pulse at intensities of gigawatts per square centimeter causes serious damage to the gain medium through nonlinear processes such as self-focusing. For example, some of the most powerful compressed CPA laser beams, even in an unfocused large aperture (after exiting the compression grating) can exceed intensities of 700 gigawatts/cm², which if allowed to propagate in air would instantly self focus and form a plasma or cause filament propagation, both of which would ruin the original beam's desirable qualities and could even cause back-reflection potentially damaging the laser's components. In order to keep the intensity of laser pulses below the threshold of the nonlinear effects, the laser systems had to be large and expensive, and the peak power of laser pulses was limited to the high gigawatt level or terawatt level for very large multi beam facilities. Gérard Mourou is a pioneer in the field of electrical engineering and lasers. ... The University of Rochester is a private, coeducational and nonsectarian research institution located in Rochester, New York. ... MacGyver is one of the symbols of the 1980s in America The 1980s decade refers to the years from 1980 to 1989, inclusive. ... In physics, power (symbol: P) is the amount of work done per unit of time. ... In physics, intensity is a measure of the time-averaged energy flux. ... The gigawatt (symbol: GW) is a unit for measuring power corresponding to one billion (109) watts. ... A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ... A laser system generally consists of three important parts: An energy source (usually referred to as the pump or pump source); A gain medium or laser medium; A mirror, or system of mirrors, forming an optical resonator. ... Nonlinear optics is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization P responds nonlinearly to the electric field E of the light. ... Nonlinear optics is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization P responds nonlinearly to the electric field E of the light. ... Look up air in Wiktionary, the free dictionary. ... A Plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentation A solar coronal mass ejection blasts plasma throughout the solar system. ... In nonlinear optics, filament propagation is propagation of a beam of light through a medium without diffraction. ... Look up Threshold in Wiktionary, the free dictionary. ...

In CPA, on the other hand, an ultrashort laser pulse is stretched out in time prior to introducing it to the gain medium using a pair of gratings that are arranged so that the low-frequency component of the laser pulse travels a shorter path than the high-frequency component does. After going through the grating pair, the laser pulse becomes positively chirped, that is, the high-frequency component lags behind the low-frequency component, and has longer pulse duration than the original by a factor of 10³ to 10⁵. Then the stretched pulse, whose intensity is sufficiently low compared with the intensity limit of gigawatts per square centimeter, is safely introduced to the gain medium and amplified by a factor of approximately 10¹⁰. Finally, the amplified laser pulse is recompressed back to the original pulse width through the reversal process of stretching, achieving orders of magnitude higher peak power than laser systems could generate before the invention of CPA. To meet Wikipedias quality standards, this article or section may require cleanup. ... A chirp is a signal in which the frequency increases (up-chirp) or decreases (down-chirp) with time. ... In signal processing and telecommunication, the term pulse duration has the following meanings: Pulse duration using 50% peak amplitude. ...

In addition to the higher peak power, CPA makes it possible to miniaturize laser systems (the compressor being the biggest part). A compact high-power laser, known as a tabletop terawatt laser (T³ laser), can be created based on the CPA technique.

Compressor and stretcher

There are many ways to construct compressors and stretchers.

The Material dispersion can be used. Depending on which frequency is higher, that of the light or that of the middle of the bandgap of the material, this results in a stretcher or compressor. In the middle is net dispersion and just below the middle is the soliton region. Glass fibres can have their dispersion tailored to meet the needs. Typically 200 mm glass are used. In optics, dispersion is a phenomenon that causes the separation of a wave into spectral components with different frequencies, due to a dependence of the waves speed on its frequency. ... In mathematics and physics, a soliton is a self-reinforcing solitary wave caused by nonlinear effects in the medium. ...

A prism or grating pair acts as a compressor. Insertion of a 1:1 telescope in 4-f configuration and mirroring the second prism/grating eliminates this effect. A smaller telescope leads to a compressor and a bigger telescope leads to a stretcher. Prisms and gratings are sometimes combined to correct higher order chirps. Typically a 10 m large prism compressor is used. If a shaft of light entering a prism is sufficiently small such that the coloured edges meet, a spectrum results In optics, a prism is a device used to refract light, reflect it or break it up (to disperse it) into its constituent spectral colours (colours of the rainbow). ... In optics, a diffraction grating is an array of fine, parallel, equally spaced grooves (rulings) on a reflecting or transparent substrate. ... 50 cm refracting telescope at Nice Observatory. ...

One or multiple reflections between a pair of chirped mirrors or similar device allow any form of chirp. This is often used in conjunction with the other techniques to correct for higher orders. Typically 10 reflections are needed, since 0.3 mm thick dielectric stacks are not manufactureable. A dielectric mirror is a special kind of a mirror. ...

In the dazzler light is going through birefringent material. A shear noise going through the crystal induces additional stress birefringence, which rotates the polarization. Typically 50 mm of birefringent material is needed.

In the spatial light modulator the light is analyzed sent through a LCD and composed back together. The bandwidht of a single element of the LCD is typically 1 nm so that the pulse time width can get 1 mm (at 1 µm central wavelength). LCD redirects here. ...

See also

• Group velocity