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Proceedings Paper

Semiconductor ring lasers with delayed optical feedback: low-frequency fluctuations
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Paper Abstract

Semiconductor lasers subject to external feedback are known to exhibit a wide variety of dynamical regimes desired for some applications such as chaos cryptography, random bit generation, and reservoir computing. Low-frequency fluctuations is one of the most frequently encountered regimes. It is characterized by a fast drop in laser intensity followed by a gradual recovery. The duration of this recovery process is irregular and of the order of hundred nanoseconds. The average time between dropouts is much larger than the laser system characteristic time-scales. Semiconductor ring lasers are currently the focus of a rapidly thriving research activity due to their unique feature of directional bistability. They can be employed in systems for all-optical switching, gating, wavelength-conversion functions, and all-optical memories. Semiconductor ring lasers do not require cleaved facets or gratings for optical feedback and are thus particularly suited for monolithic integration. We experimentally and numerically address the issue of low-frequency fluctuations considering a semiconductor ring laser in a feedback configuration where only one directional mode is re-injected into the same directional mode, a so-called single self-feedback. We have observed that the system is very sensitive to the feedback strength and the injection current. In particular, the power dropouts are more regular when the pump current is increased and become less frequent when the feedback strength is increased. In addition, we find two different recovery processes after the power dropouts of the low-frequency fluctuations. The recovery can either occur via pulses or in a stepwise manner. Since low-frequency fluctuations are not specific to semiconductor ring lasers, we expect these recovery processes to appear also in VCSELs and edge-emitting lasers under similar feedback conditions. The numerical simulations also capture these different behaviors, where the representation in the phase space of the carriers versus the round trip phase difference gives additional insight into these phenomena. This proceedings paper gives a short overview of the results of L. Mashal et al. [L. Mashal et al., IEEE J. Quantum. Electron. 49, 790, 2013].

Paper Details

Date Published: 2 May 2014
PDF: 8 pages
Proc. SPIE 9134, Semiconductor Lasers and Laser Dynamics VI, 91341Y (2 May 2014); doi: 10.1117/12.2052002
Show Author Affiliations
Guy Van der Sande, Vrije Univ. Brussel (Belgium)
Lilia Mashal, Vrije Univ. Brussel (Belgium)
Romain Modeste Nguimdo, Vrije Univ. Brussel (Belgium)
Miguel C. Cornelles-Soriano, Instituto de Física Interdisciplinar y Sistemas Complejos (Spain)
Jan Danckaert, Vrije Univ. Brussel (Belgium)
Guy Verschaffelt, Vrije Univ. Brussel (Belgium)


Published in SPIE Proceedings Vol. 9134:
Semiconductor Lasers and Laser Dynamics VI
Krassimir Panajotov; Marc Sciamanna; Angel Valle; Rainer Michalzik, Editor(s)

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