Low-frequency self-pulsing in single-section quantum-dot laser diodes and its relation to optothermal pulsations

Tierno, A., Radwell, N. and Ackemann, T. (2011) Low-frequency self-pulsing in single-section quantum-dot laser diodes and its relation to optothermal pulsations. Physical Review A: Atomic, Molecular and Optical Physics, 84(4), 043828. (doi: 10.1103/PhysRevA.84.043828)

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Abstract

Self-sustained pulsations in the output of an InAs quantum dot laser diode in the MHz range are reported. The characteristics (shape, range, and frequency) are presented for the free-running laser and when optical feedback in the Littrow configuration is applied. Bistability in the light-current characteristics is observed for operating wavelengths smaller than the gain peak, but it is not present for wavelengths above the gain peak and for the free-running laser, except at elevated temperatures. The temporal evolution of the envelopes of the optical spectra is very different for operation below, around, and above the gain peak, which might be related to a change of phase-amplitude coupling across the gain maximum, in agreement with the expectation for a two-level system. The time scale and the bifurcation scenario, supported by an initial blueshift of the emission wavelength of each longitudinal mode in time-resolved optical spectra, suggests that these are optothermal pulsations similar to those reported in quantum well amplifiers [Phys. Rev. E 68, 036209 (2003)]. The mechanism of pulsation seems to be a destabilization of bistable states (due to saturable absorption in the beam wings) by a slow thermal change in the waveguiding properties.

Item Type:Articles (Letter)
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Radwell, Dr Neal
Authors: Tierno, A., Radwell, N., and Ackemann, T.
Subjects:Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review A: Atomic, Molecular and Optical Physics
Publisher:American Physical Society
ISSN:1050-2947
ISSN (Online):1094-1622

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