Spatial Multiplexing of Temporal Localized Structures in Degenerate Optical Cavities

Temporal localized structures (TLS) are individually addressable pulses circulating in an optical cavity [1]. Their existence is related to the presence of a generalized multistability between pulsating emission states having different number of pulses per roundtrip. They appear in passively mode-locked Vertical External-Cavity Surface-Emitting Lasers (VECSELs) when i) the cavity roundtrip $(\tau_{\mathrm{c}})$ is larger than the carrier recovery time (typically 1 ns) and ii) the saturable absorber mirror (SESAM) exhibits a modulation depth above a critical value (typically 8%) [2], [3]. When the external cavity is nearly degenerate, i.e. close to self-imaging condition, temporal-localized patterns are observed [4]. On the other hand, degenerate cavities enable arbitrary spatial shaping of the lasing emission profile [5].