CW metal vapor ion lasers

The 4416Å transition in CdII was the first metal vapor system to exhibit CW laser action. The system appears to be one of the most simple and efficient lasers operating in the visible region of the spectrum. At the present time, peak powers of 100 mW and gains as high as 35% per meter have been observed along with relatively high efficiencies. The laser has been successfully operated without the use of an externally controlled furnace by thermally insulating the discharge region and using the discharge current to heat the metal to the necessary vapor pressure. The excitation mechanism is believed to be a Penning ionization in the form of a He metastable colliding with a neutral metal atom and exciting it to the upper laser level of the ion. The excess energy is taken up by the ejected electron. This mechanism can be applied to other metal vapor systems and several new CW laser transitions will be discussed.