A regenerative power amplifier operating on the blue-green line of the nitrogen ion laser

Operation of the nitrogen ion laser as an optical regenerative amplifier driven by a master oscillator allows the output to be effectively switched into the blue-green region of the spectrum. In this work an amplifier containing a dilute plasma of nitrogen ions was pumped by thermolecular charge transfer from He2+ produced by an intense e-beam propagating through several atmospheres pressure of gas mixture. The injection of relatively broadband output from a dye laser oscillator caused the output from the amplifier to switch entirely into the (0,2) vibrational component of the B→X electronic transition of N+2 at 470.9 nm. An output linewidth of 0.007 nm was achieved together with the early saturation of the laser transition needed for the extraction of power from the amplifier at optimal efficiency.