Collisionally excited extreme ultra-violet lasers created by laser irradiation of plasmas

Short wavelength extreme ultra-violet (EUV) lasers pumped by electron collisional excitation in plasmas irradiated by infra-red lasers have achieved saturated output down to wavelengths as short as 5.9 nm and are now used for applications. These lasers operate without mirrors with output due to amplified spontaneous emission (ASE). The beam profiles consist typically of a large number of individual coherent beamlets with a total near-field profile that is typically crescent shaped. Gain profiles are spectrally narrow dependent on thermal Doppler broadening of ions of temperature ~ 100-200 eV. With gain narrowing, this result in pulses of spectral width v/Deltav > 104. The shortest pulse durations of the output EUV lasers have consequently been close to Fourier transform limited at ap 3 ps.