Generation of stable Ps, mJ pulses at high repetition rate for ultrafast diagnostic experiments: Final report

Technical Report · Wed Oct 01 00:00:00 EDT 1986

DOI:https://doi.org/10.2172/7163169· OSTI ID:7163169

Mourou, G

Nd:Glass amplifiers have very good energy storage capabilities (5 J/cm/sup 2/), but, the energy extraction is extremely inefficient for short-pulse amplification. At relatively high peak intensities of approx. 10 GW/cm/sup 2/, nonlinear phase shifts occur, leading to beam wavefront distortion which can result in filamentation and irreversible damage. In order that the peak intensity in the amplifier remain below this damage level, a picosecond pulse can be amplified only to an energy density of approx. 10 mJ/cm/sup 2/, two orders of magnitude less than the stored energy level of 5 J/cm/sup 2/. We have developed an amplification system, which uses an optical pulse compression technique to circumvent this peak power limitation. This technique is analogous to a method developed over forty years ago for the amplification of radar pulses. Briefly: a long optical pulse is deliberately produced by stretching a short, low-energy pulse, amplified and then compressed. The frequency chirp and the temporal broadening are produced by propagating a high-intensity pulse along a single-mode fiber. At the beginning of the fiber, the pulse undergoes self-phase modulation which produces a frequncy chirp. The chirp is then linearized by the group-velocity dispersion of the fiber. This long, frequency-chirped, pulse is amplified, and then compressed to a pulsewidth approximately equal to 1/..delta..f, where ..delta..f is the chirped bandwidth. With this system, short pulses can reach the high saturation energy levels, with moderately low peak power levels being maintained in the amplifying medium.

• Research Organization: Rochester Univ., NY (USA). Lab. for Laser Energetics
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7163169
• Report Number(s): UCRL-15849; ON: DE87002683
• Country of Publication: United States
• Language: English

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