Abstract

Quantum-dot (QD) based lasers exhibit rich behaviors due to their unique carrier dynamics [1], including chaos in solitary in QD vertical-cavity surface-emitting lasers [2] or simultaneous emission from ground (GS) and excited state (ES). Recently, it has been shown that time-delayed optical feedback (OFB) can induce GS to ES emission-state switching with complete extinction of the other state [3]. In this work we investigate experimentally and by simulations a two-state QD laser subject to OFB and report incomplete and recurrent GS-ES emission switching induced by variations of the feedback (FB) phase. The QD laser consists of 5 layers of undoped InAs QDs separated by GaAs barriers. The cavity is biased homogeneously. It has a total length of 1 mm and a width of 4 µm, and the facets are uncoated. The QD laser emits ES emission at room temperature (λ_ES = 1.17 µm), but simultaneous GS-ES emission (λ_ES = 1.25 µm) at a temperature of 8 ^◦C. The experimental setup is depicted in Fig. 1. The EC length is around 20 cm and a variable neutral density filter is used to control the FB strength. Emission is analyzed by a power meter and an optical spectrum analyzer. A piezo-electric actuator is used to adjust the EC length at the micrometer level.

© 2015 IEEE