Ionization Compression of High Power Picosecond CO2 Laser

• Main Authors: Johnson, L. A., Gordon, D. F., Palastro, J. P., Hasson, V.
• Format: Conference Proceeding
• Language: English
• ISSN: 2576-7208
• DOI: 10.1109/PLASMA.2017.8496301

Ultra-short pulse lasers are dominated by solid-state technology, which typically operates in the near-infrared. Efforts to extend this technology to longer wavelengths are meeting with some success, but the trend remains that longer wavelengths correlate with greatly reduced power. The carbon dioxide (CO 2 ) laser is capable of delivering high energy, 10μm wavelength pulses, but the gain structure makes operating in the ultra-short pulse regime difficult. The U.S. Naval Research Laboratory is currently building a novel CO 2 laser which uses solid state injection seeding, with pressure and power broadening, to generate high power, picosecond pulses. As a way of relaxing the requirements on the seed pulse and gain medium, we propose to use ionization blue-shifting during pre-amplification to broaden the laser bandwidth. The time changing index of refraction associated with laser-plasma generation will spectrally blue-shift the pulse. This can be dispersively compressed outside of the amplifier. This mechanism was proposed [1] to explain the observation of 600fs pulses generated by a high pressure CO 2 laser. We carried out simulations using a modified version of the co2amp code [2] which models CO 2 pumping with the Boltzmann equation, laser amplification with the Maxwell- Bloch equations, and beam propagation with Huygens-Fresnel integration, and now photoionization and collisional ionization.