Averaged models for passive mode-locking using nonlinear mode-coupling

An averaged mode-locking model is presented in which the nonlinear mode-coupling behavior in a wave-guide array, dual-core fiber, and/or fiber array is used to achieve stable and robust passive mode-locking. By using the discrete, nearest-neighbor spatial coupling of these nonlinear mode-coupling devices, low-intensity light can be transferred to the neighboring wave-guides and attenuated. In contrast, higher intensity light is self-focused in the launch wave-guide and remains largely unaffected. This nonlinear effect, which is described by linearly coupled nonlinear Schrödinger equations, leads to the temporal intensity discrimination required in the laser cavity for mode-locking. Computations of this pulse shaping mechanism show that stable and robust mode-locked soliton-like pulses can be produced in this master mode-locking model.