CO 2 Laser


Tabletop Terawatt CO2 |Optical Switching | CO2 Laser Oscillator | CO2 Laser Amplifier |Bandwidth Limitation

 

CO2 Laser Amplifier

To reach a power level needed for laser accelerator studies, the sliced picosecond CO2 laser pulse is amplified 104-105 times. A 3-atm CO2 amplifier with the active volume of 120x5x2 cm3 pumped by a UV-preionized 150-kV transverse electrical discharge serves for that purpose. The amplifier optical setup consists of two parts: regenerative and multi-pass. With a help of two quarter-wave Pockels cells the injected laser pulse is trapped inside the regenerative cavity and is extracted after the controlled number of double passes (normally five). The output energy is limited by the damage threshold of the Pockels crystal to ~10 mJ. However, this brings the output only part ways towards the desired power level. The four extra passes through the amplifier are arranged in a double-X configuration using a 4-mirror set-up, as shown in Figure. We must address the problem of preventing parasitic self-lasing caused by the extremely high gain conditions. This problem is solved by placing a saturable absorber cell and a plasma switch in the way of the regeneratively amplified beam before redirecting it for the next four passes through the amplifier. The dense plasma of the laser spark, created at the focal point of a telescope inside the plasma switch, blocks the passage of parasitic radiation recycling through the amplifier. The plasma breakdown also shortens the width of the amplified pulse.

Ultimately, after 4 additional passes through the same amplifier we measure an output laser energy of 1 J. A single-shot autocorrelator indicates that the laser pulse width is 100 ps, which corresponds to the spectral-bandwidth-limited minimum pulse duration sustainable by the 3-atm CO2 amplifier. The corresponding peak power is 10 GW.

 

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Last Modified: May 12, 2006
Please forward all questions about this site to: Vitaly Yakimenko