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The short pulse laser at MEC is a double-CPA laser designed to operate at >25 TW peak power, with < 40 fs pulse duration and > 1 J per pulse. A schematic of the laser system is shown in Figure 1. A commercial CPA (Legend) system, seeded by an oscillator that is RF locked to LCLS, generates mJ-level compressed pulses, which are passed through an OPA pulse cleaning system before being stretched again for further amplification. The first bowtie amplifier operates at 120 Hz, matching the LCLS x-ray pulse rate, outputting >10 mJ per pulse. A second bowtie stage amplifies to >1.5 J at 5 Hz repetition rate. After compression, this yields > 1 J in 40 fs, for 25 TW peak power.
Figure 1. Diagram of the MEC short pulse laser system.
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The final output has a pulse duration of approximately 35-55 fs, with a beam diameter of 65 mm, and an energy of 1 J. The compressor grating spacing can be adjusted to produce between 35 fs and 8 ps pulses. For pulses of longer duration, stretched pulses with 150 ps duration have been provided successfully.
Figure 2. (legacy information: please contact) Wizzler measurement of the pulse shape of the MEC short pulse laser indicating compression to nearly transform-limited pulse at 23 nm bandwidth.
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