Recent developments of capacitively coupled radio-frequency excited ion gas lasers

This is a review of the recent investigations on He-Cd+, He-Kr+, He-Ar+, He-Se+ and He-Cu+(CuBr) lasers excited with the transverse capacitively coupled radio-frequency discharge. The recent investigations show that the designs and operation of the radio-frequency excited lasers are much simpler than those of the hollow-cathode discharge lasers at the similar laser output parameters. Under single-line operation the radio-frequency excited He-Cd+ laser deliveres output powers of 60 mW at 441.6 nm, 36 mW at both 533.7 nm and 537.8 nm, and 14 mW at both 635.5 nm and 636.0 nm. The output powers of the He-Kr+ laser is 22 mW at 469.4 nm, and 11 mW at 431.8 nm. Both lasers exhibite the rms noise-to-signal ratio (0.4-0.6 %) much lower than that of conventional positive column He-Cd+ lasers. These make the radio-frequency excited ion gas laser attractive for practical applications.