Theoretical and Experimental Investigation of Unidirectionality in an Integrated Semiconductor Ring Mode-Locked Laser With Two Saturable Absorbers

The lack of integrated optical isolators in standard integrated semiconductor photonics platforms leaves integrated lasers vulnerable to back reflections. A hypothesis is that by making a ring laser operate unidirectionally, external reflections will couple back into the non-lasing direction, and the sensitivity toward reflections will be reduced. In this paper, unidirectionality is pursued by pla...