Abstract

Single longitudinal mode (SLM) gain-switched tunable lasers are required for a range of applications in fundamental and applied spectroscopy. The grazing incidence configuration has been successfully used to achieve SLM laser operation of Ti:sapphire lasers and OPOs. However, efficiencies are typically low with a high pump threshold energy, often close to the damage levels of cavity components. Lower thresholds and higher laser efficiencies can be obtained using coupled gain- switched lasers based on the Michelson Interferometric (MI) cavity [1] or Michclson-Fox-Smith (MFS) cavity [2]. The longitudinal mode spacing of these coupled resoantors is typically described in terms of either a self-seeded theory, where a pulse building up in the dispersive cavity arm seeds the broadband cavity arm [1] or a coupled cavity which allows for simultaneous laser pulse build up in all cavity arms, and to additional mode selection [2]. However, no comprehensive model has been presented to allow the dominant mechanism to be determined for a particular case We have developed a model which allows the behaviour of arbitrary multi-arm coupled gain-switched lasers to be predicted We have used the model to develop an enhanced MFS resonator for low gain media, as well as a new coupled resonator for higher gain materials.

© 2000 IEEE