Discrete Relaxation Oscillation Frequency Hopping in Delayed-feedback Semiconductor Lasers

International audienceWe study the dynamics of semiconductor lasers subject to strong delayed optical feedback. We find that the discrete nature of the external-cavity modes leads to a discrete set of relaxation oscillation frequencies observed at the onset of the first instability as the pump current is increased. This explains experimentally observed hops between the frequencies

Emergence of resonant mode-locking via delayed feedback in quantum dot semiconductor lasers

With conventional semiconductor lasers undergoing external optical feedback, a chaotic output is typically observed even for moderate levels of the feedback strength. In this paper we examine single mode quantum dot lasers under strong optical feedback conditions and show that an entirely new dynamical regime is found consisting of spontaneous mode-locking via a resonance between the relaxation oscillation frequency and the external cavity repetition rate. Experimental observations are supported by detailed numerical simulations of rate equations appropriate for this laser type. The phenomenon constitutes an entirely new mode-locking mechanism in semiconductor lasers.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Injection-induced, tunable, all-optical gating in a two-state quantum dot laser

We demonstrate a tunable all-optical gating phenomenon in a single-section quantum dot laser. The free-running operation of the device is emission from the excited state. Optical injection into the ground state of the material can induce a switch to emission from the ground state with complete suppression of the excited state. If the master laser is detuned from the ground-state emitting frequency, a periodic train of ground-state dropouts can be obtained. These dropouts act as gates for excited-state pulsations: during the dropout, the gate is opened and gain is made available for the excited state, and the gate is closed again when the dropout ends. Numerical simulations using a rate equation model are in excellent agreement with experimental results.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Dual state antiphase excitability in optically injected quantum dot lasers

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Lasing state hysteresis in a two-state quantum dot laser via optical injection

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Optically induced hysteresis in a two-state quantum dot laser

Quantum dot lasers can lase from the ground state only, simultaneously from both the ground and first excited states and from the excited state only. We examine the influence of optical injection at frequencies close to the ground state when the free-running operation of the device is excited state lasing only. We demonstrate the existence of an injection-induced bistability between ground state dominated emission and excited state dominated emission and the consequent hysteresis loop in the lasing output. Experimental and numerical investigations are in excellent agreement. Inhomogeneous broadening is found to be the underlying physical mechanism driving the phenomenon.SCOPUS: ar.jinfo:eu-repo/semantics/publishe