Chirped Pulse Amplification Technique Research Articles

Terawatt to Petawatt Subpicosecond Lasers

The application of the chirped-pulse amplification technique to solid-state lasers combined with the availability of broad-bandwidth materials has made possible the development of small-scale terawatt and now even petawatt (1000-terawatt) laser systems. The laser technology used to produce these intense pulses and examples of new phenomena resulting from the application of these systems to atomic and plasma physics are described.

Femtosecond free-electron laser by chirped pulse amplification.

In this work we combine elements of chirped pulse amplification techniques, now familiar in solid-state lasers, with an amplifier based upon a seeded free-electron laser (FEL). The resulting device would produce amplified pulses of unprecedented brevity at wavelengths shorter than can be currently obtained by any tunable laser system. We use a subharmonically seeded FEL to illustrate the concept. Radiation from a Ti:sapphire laser is frequency tripled and stretched optically to provide a coherent seed pulse for the FEL. When coupled to an electron beam inside a magnetic wiggler, the seed radiation introduces an additional energy modulation on the electron bunch, which has been prepared with an energy chirp to match the chirp in the optical pulse. The energy modulated electrons are then spatially bunched in a dispersion magnet and introduced to a wiggler configured to be resonant to a harmonic of the seed laser, providing additional frequency multiplication. The coherent radiation produced by these electrons is amplified as it traverses the wiggler and is recompressed optically. The preservation of phase coherence provided by this scheme results in a device which can yield 4-fs pulses with 0.3 mJ at a central wavelength of ca. 8 nm, easily the shortest duration of amplified pulses produced by any laser. In this paper we discuss various aspects of the concept, including the generation of short pulses, temporal stretching and compression, and potential applications of the device. The phase distortion during the wide bandwidth FEL amplification is discussed in detail, and is shown to be within the bounds required to produce a 4-fs pulse upon compression.

High contrast multi-terawatt pulse generation using chirped pulse amplification on the VULCAN laser facility

High power (8 TW), ultra-short (2.4 ps), pulses have been generated using chirped pulse amplification techniques on the VULCAN Nd: glass laser. A novel oscillator was developed as a driver producing ≈ ps pulses at 105 nm. The oscillator output was stretched prior to amplification and compressed at an aperture of 150 mm. The contrast ratio obtained was ≈ 10 6, which is suitable for laser plasma interaction studies.

Ring-Type Ti:sapphire Regenerative Amplifier with a Wide Tuning Range

Using a chirped pulse amplification technique, we have constructed a Ti:sapphire regenerative amplifier with a ring cavity. The amplified pulses with an energy of 4 mJ were compressed to 120 fs at 797 nm and 170 fs at 746 nm. The spectral distortion in the amplifier and the compressed pulse shapes were investigated at the two different wavelengths.

Chirped pulse amplification in Er-doped fibers

Efficient amplification of ultrashort pulses in Er-doped fibers is difficult to realise because of temporal and spectral distortions which result from the influence of the intrinsic fiber nonlinearities. Using numerical calculations we show that the deleterious influence of the fiber nonlinearities can be suppressed to a large extent by applying the chirped pulse amplification technique. Our results demonstrate that practically distortionless and highly efficient amplification of ultrashort pulses in fiber amplifiers can be achieved in this way.

Experimental program on the 20 TW laser system

Pulses of 20 TW have been generated at 1064 nm using the chirped pulse amplification technique coupled to a 90 mm output aperture Nd–silicate glass amplification line. The chirped pulses are compressed to 1.2 psec with an energy of 24 J using large holographic gold-coated 1740 lines/mm diffraction gratings. In a first step, the beam is focused by an aspherical lens, but the maximum measured irradiance is limited to 1018 W/cm2 by self-focusing effects in the air path and in the lens. Higher values up to 1019 W/cm2 will need propagation of the compressed beam in vacuum and focusing by reflective optics. The first experiments deal with laser–plasma coupling, with emphasis on the power contrast ratio. Further plans include multiple Compton scattering and x-ray laser generation. Theoretical works on ionization processes and particle accelerator are also presented.

Design and performance of a multiterawatt, subpicosecond neodymium:glass laser

A tabletop Nd: phosphate glass laser system capable of producing subpicosecondpulses with a peak power > 8.5 TW is described. Relay imaging and optimization of the chirped-pulse amplification technique, including spectral shaping and careful attention to beam quality, produce a transform-limited, 800-fs compressed pulse with an energy of 6.8 J in a near-diffraction-limited spatially uniform beam.

05-TW, 125-fs Ti:sapphire laser

We describe a terawatt, femtosecond laser system based on Ti:sapphire amplifiers and the technique of chirpedpulse amplification. The laser output at 807 nm contains 60 mJ of energy in a 125-fs pulse duration. The laser beam is nearly diffraction limited and may be focused to an intensity of 10(18) W/cm(2) with an f/6 optic.

Generation of ultrahigh peak power pulses by chirped pulse amplification

Single picosecond pulses have been amplified to the terawatt level by a table-top-size Nd:glass amplifier by using the technique of chirped pulse amplification (CPA). The divergence of the beam is twice the diffraction limit, making the brightness of this source equal to approximately 2*10/sup +18/ W/(cm-sr), which is thought to be the highest brightness yet reported. The CPA technique allows the efficient energy extraction from extremely compact amplifier systems. Amplification of chirped pulses over nine orders of magnitude, i.e. from nanojoule to the joule level, has been demonstrated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>