Two-dimensional analysis of self-sustained pulsation for narrow-stripe AlGaAs lasers

Self-sustained pulsation in narrow stripe geometry AlGaAs laser diodes is investigated numerically and experimentally. By taking account of the time-dependent two-dimensional optical field, carrier spreading in the cladding layers, and multilongitudinal modes, we succeeded in clarifying the mechanism for the pulsation. Fluctuation of the optical field plays an important role in forming saturable absorption. The numerical analysis clearly shows that our newly proposed real refractive index-guided structure is very suitable for a pulsation laser in which the optical field distribution and current spreading can be independently controlled. Furthermore, me show that the new structure gives much lower threshold current than that of a conventional loss-guided structure. These predicted advantages of the real refractive index-guided structure are verified experimentally with good agreement