High-power operation of self-sustained pulsating AlGaAs semiconductor lasers with multiquantum well active layer

Improvement of kink level in self-sustained pulsating multiquantum well (MQW) lasers is mainly examined by controlling the built-in refractive index difference parallel to the junction. Furthermore, it is shown that the offset power level of self-pulsation is suppressed by increasing the effective refractive index difference. Kink level can be improved to over 30 mW in lasers without facet coatings. Relative intensity noise of 10⁻¹³ Hz⁻¹ under optical feedback of 3∼4% is also attained from 4 to 7 mW. With antireflective and reflective facet coatings, stable transverse-mode operation over 70 mW is achieved.