Gain switching of unidirectional erbium-doped waveguide ring lasers

Gain switching of unidirectional erbium-doped waveguide ring lasers is studied using numerical simulations based on the time-dependent rate-propagation equations. The counter-directional wave suppression is analyzed for different waveguide ring cavity configurations and pumping schemes. It is shown that for the one-end pumped gain-switched erbium-doped waveguide ring laser, highly unidirectional operation is possible with no intra-cavity elements included. In this case the counter-directional wave suppression considerably exceeds its steady-state value. If the unidirectional operation is caused by the deliberately introduced intra-cavity elements, the gain-switched suppression remains close to the steady-state value.