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?CO₂ Laser development

Hubertus von Bergmann

Research and development on transversely excited atmospheric (TEA) and high pressure (HP) CO₂ laser systems did continue during 2017. This work is done jointly with our industrial partner PaR System based in Pretoria, who is the only manufacturer in the world that offers high pressure CO₂ laser systems.

The project currently aims at the development of large aperture, very high pressure CO₂ lasers to be employed as amplifiers in terawatt peak power, ultrashort pulse amplifier systems at 10 ?m in the mid-infrared, generating pulse durations down to a few picoseconds. In order to amplify such short pulses a gain bandwidth of several hundred GHz is required. This can be obtained from HP CO₂ lasers by operating them at gas pressures of more than 10 bar, where pressure broadening of the emission lines causes overlap of all the branch lines of an emission band, generating a gain bandwidth of up to 1 TW.

During 2016 we reported initial results obtained from a thyratron switched discharge test system, capable of stable operation at gas pressures of up to 12 bar with the large discharge cross-section of 22×22 mm. The system is excited by a high voltage thyratron switched LC-Inversion pulser delivering excitation pulses of up to 140 kV. During the reporting period of 2017 the system has now been fully characterised in respect of discharge stability, electrode breakdown voltage and small-signal gain. This has resulted in valuable design data for the full size amplifiers which are currently build by PaR Systems at their production site in Pretoria.

In addition, during 2017 Prof von Bergmann has again been consulting for PaR Systems on the design and construction of high power CO₂ laser systems. This consultation does allow some of our technical staff, especially Gerhard Louwrens, to generate supplementary income. Due to the limited time duration of the current projects, there were again no students involved during 2017.