Tunable, single axial mode LiF:F super(-) sub(2) laser

We have developed a gain-switched room temperature single axial mode LiF:F super(-) sub(2) sub( )laser using a coupled narrowband resonator. The resonator uses a classic four-prism achromatic beam expander /Littrow grating configuration, augmented with a dichroic mirror that defines a coupled resonator with: (1) reduced threshold and higher efficiency, and (2) dramatically increased axial mode separation for enhanced mode selectivity. One etalon was then sufficient to achieve single axial mode output with < 100 MHz bandwidth and an energy conversion efficiency of 5.5%, significantly higher than previously reported for narrowband LiF:F super(-) sub(2) lasers where only a bandwidth of 300 MHz had been achieved. The single longitudinal mode laser was tunable in single mode between 1120 and 1200 nm. A coupled cavity model was developed to explain the experimentally observed mode structure, and to allow similar coupled resonators to be optimised for other vibronic laser media. copyright 2002 Elsevier Science B.V. All rights reserved.