CW radio-frequency excited white-light He-Cd/sup +/ laser

We report on the design and performance of a continuous-wave transverse capacitively coupled radio-frequency excited He-Cd/sup +/ laser, which is capable of simultaneously delivering stable, tens-milliwatt power output at the three primary spectral lines blue: (/spl lambda/=441.6 nm), green (/spl lambda/=533.7 nm and /spl lambda/=537.8 nm), and red (/spl lambda/=635.5 nm and /spl lambda/=636.0 nm). Mixing these lines can result in the laser beam featured by a wide band of colors, including white color. The radio-frequency discharge, that excited the He-Cd mixture inside an alumina ceramic tube (400 mm length and 4 mm inner diameter) inserted into the fused silica tubing, operated between 400 mm long and 4 mm wide outer electrodes. Transformation of the radio-frequency discharge impedance to the 50-/spl Omega/ output resistance of the radiofrequency generator and symmetrization of the radio-frequency voltage were performed by a special matching circuit. Under single-line operation the He-Cd/sup +/ laser output powers of 60 mW, 38 mW and 14 mW were obtained for the blue, green and red lines, respectively, at an input radio-frequency power of 400 W. Owing to the power interaction between the laser oscillations at red and green higher laser output powers in red and green are possible under multi-line operation. At optimum conditions the white-light laser output power of about 60 mW is obtainable from the laser tube of 40 cm active length. The rms noise-to-signal ratio (lower than 0.4%) of the laser output power of the radio-frequency excited He-Cd/sup +/ laser was comparable to that of hollow cathode He-Cd/sup +/ lasers and much lower than that of conventional positive column He-Cd/sup +/ lasers. The presented laser has exhibited stable operation for more than 400 hours, showing ability to become a long life laser.<
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