Progress on developing a petawatt laser source in 10μm region is described. Analysis of optical pumping N2O containing active media by pulsed multifrequency HF laser has been performed. It is shown that amplification of ultrashort pulses should be carried out in the gain band centered at 930cm-1. Amplification of seed ultrashort (7sim;lps) pulses in atmospheric and high pressure N2O (up to 5atm) amplifiers pumped by powerful pulsed HF chemical lasers is theoretically studied. It is shown that N2O atmospheric pressure amplifiers can be effectively used for production output energy of IkJ. We discuss a simple add for subpicosecond N2O- laser system to generate joule-level 200 fs pulses with high temporal quality and an overall conversion efficiency of 80%. Petawatt class N2O laser could be prospective for strong-field physics applications and production of high energy proton beams upon irradiating gas jets.