“…The simulation of a laser during typical 3 ns transient time which, usually, is just enough to simulate the switching on of the laser or the relaxation of the device towards some new attractor after a change of parameters requires ∼ 0.5 · 10 5 time iterations and can be performed on a single processor computer in, approximately, 4-5 hours [13]. Some speed-up of computations can be achieved by using problem-dependent relations of the grid steps, including also variable steps in lateral direction of the device [7,9]. All these grid optimizations, however, are not sufficient once one-or a few-parameter studies should be performed (they can correspond to simulation times ∼1000 ns) The required results can only be computed in acceptable time by using parallel computers and parallel solvers.…”