Chirped-pulse amplification

Pessot M, Squier J, Mourou G and Harter D 1989 Chirped-pulse amplification of 100 fsec pulses Opt. Lett. 14 797-9... 

Le Blanc C, Grillon G, Chambaret J P, Migus A and Antonetti A 1993 Compact and efficient multipass Ti sapphire system for femtosecond chirped-pulse amplification at the terawatt level Opt. Lett. 18 140-... 

The layout of the experimental set-up is shown in Figure 8-3. The laser source was a Ti sapphire laser system with chirped pulse amplification, which provided 140 fs pulses at 780 nm and 700 pJ energy at a repetition rate of 1 kHz. The excitation pulses at 390 nm were generated by the second harmonic of the fundamental beam in a 1-nun-thick LiB305 crystal. The pump beam was focused to a spot size of 80 pm and the excitation energy density was between 0.3 and 12 ntJ/crn2 per pulse. Pump-... 

Tanabe T, Ohno K, Okamoto T, Yamanaka M, Kannari F (2004) Feedback control for accurate shaping of ultrashort optical pulses prior to chirped pulse amplification. Jpn. J. Appl. Phys. 43 1366-1375... 

Recent developments in ultrashort, high-peak-power laser systems, based on the chirped pulse amplification (CPA) technique, have opened up a new regime of laser-matter interactions [1,2]. The application of such laser pulses can currently yield laser peak intensities well above 1020 W cm 2 at high repetition rates [3]. One of the important features of such interactions is that the duration of the laser pulse is much shorter than the typical time scale of hydrodynamic plasma expansion, which allows isochoric heating of matter, i.e., the generation of hot plasmas at near-solid density [4], The heated region remains in this dense state for 1-2 ps before significant expansion occurs. 

The experiments were performed with the JAERI (Kyoto, Japan) 100 TW Tiisapphire laser system, based on the technique of chirped pulse amplification, which was designed to generate 20-fs pulses centered at 800 nm at... 

This was first achieved by the Teramobile system [14]. The laser itself is based on the chirped pulse amplification (CPA) technique [33,34], with a Ti Sapphire oscillator and a Nd YAG pumped Ti Sapphire amplification chain. It provides 350 mJ pulses with 70 fs duration resulting in a peak power of 5 TW at a wavelength around 800 nm, with a repetition rate of 10 Hz. Its integration in the reduced space of the mobile laboratory required a particularly compact design (Fig. 14.6). The classical compressor set-up has been improved into a chirp generator to pre-compensate the group velocity dispersion (GVD) in air. Combined with an adjustable focus, this permits to... 

P. Maine, D. Strickland, P. Bado, M. Pessot, G. Mourou, Tabletop terawatt laser by chirped pulse amplification, IEEE Journal of Quantum Electronics 24, 398 (1988)... 

Figure 6 Block diagram of the two-color optical parametric amplifier (OPA) and IR-Raman apparatus. CPA = Chirped pulse amplification system Fs OSC = femtosecond Ti sapphire oscillator Stretch = pulse stretcher Regen = regenerative pulse amplifier SHGYAG = intracavity frequency-doubled Q-switched Nd YAG laser YAG = diode-pumped, single longitudinal mode, Q-switched Nd YAG laser KTA = potassium titanyl arsenate crystals BBO = /J-barium borate crystal PMT = photomultiplier tube HNF = holographic notch filter IF = narrow-band interference filter CCD = charge-coupled device optical array detector. (From Ref. 96.)...

Rudd JV, Korn G, Kane S, Squier J, Mourou G, Bado P. Chirped-pulse amplification of 55 fs pulses at a 1 kHz repetition rate in a Ti Al203 regenerative amplifier. Opt Lett 1993 18 2044-2046. 

The emergence in the late 1980s of chirped pulse amplification techniques [1] meant that it was now possible to produce focused laser intensities well in excess of 10 W/cm. This is equivalent to a laser electric field approaching one atomic unit and it is perhaps not surprising, therefore, that conventional perturbation theory cannot be applied to the dynamics of atoms and molecules in such intense laser fields. In fact these fields dress the electrons and nuclei on a timescale that is short compared to those of conventional atomic or molecular processes and new non-linear phenomena are observed. 

An example of a femtosecond laser system employing chirped pulse amplification is the one housed at the Laser Support Facility at the Rutherford Appleton Laboratory a schematic layout is shown in Fig. 2. The system is essentially two-stage, with short, low energy pulses generated in the first stage and amplified in the second. To generate the pulses, a multi-line argon-ion laser with principal lines at 488 and 514 nm and 5 W continuous wave output is used to... 

Chirped pulse amplification is achieved using a pulsed traveling wave tube amplifier (TWTA, Amplifier Research 1000TP8G18) with peak power or 2 kW (7-18 GHz). The final pulse is shown as an inset in Figure 1. The spurious signals in the pulses we create using this technique are at least 20 dB lower in power than the instantaneous sweep frequency across the full 11 GHz range of the pulse. 

Employing the chirped pulse amplification technique [8], typically an increase of the pulse energy from the nj- to the mj-level at repetition rates of the order of kHz can be achieved, i.e., average powers of W are obtained. A scheme of the chirped pulse amplification technique is depicted in Fig. 3. The basic idea is to stretch the pulses temporally prior to amplification to avoid nonlinear effects or even damage in the amplification crystal. After... 

Near-IR solid-state lasers (e.g., Ti sapphire) with chirped pulse amplification produce laser light with high brightness and very short pulses around 800 nm [ 116]. 150 fs laser pulse experiments on PI, polycarbonates (PC), PET, and PMMA have shown an increase in the single pulse ablation threshold from 1 J/cm for PI to 2.6 J/cm for PMMA. This corresponds well with the optical bandgaps of these polymers and indicates a multiphoton process. Incubation effects were observed for all polymers, but are more pronounced for PMMA, PC, and PET than for PI and PTFE, which are more stable [117-120]. Clear signs of molt redeposition of material can be observed for all polymers, except PI, which is not surprising, as it decomposes and does not melt. 

Chirped pulse amplification (CPA) [1,2] is a new technique to achieve extremely high optical intensities in compact laser systems. The basic idea, which has its counterpart in radar technology, is illustrated in Fig. 1 [3]. An initial, short pulse... 

Fig. 1. Basic principle for chirped pulse amplification showing the stretching, amplification and compression stages (From Ref. [3]).

Fig. 2. Lay-out of the Lund High-Power Laser Facility terawatt system, which operates with chirped-pulse amplification in titanium-doped sapphire (Adopted from Ref. [3]).

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