Generation of optical pulses in VCSELs below the static threshold using asymmetric current modulation.
We present a novel method for the generation of sub-nanosecond optical pulses in directly modulated vertical-cavity surface-emitting lasers (VCSELs) that operate, on average, below the cw threshold. Using the spin-flip model we demonstrate that irregular optical pulses in two orthogonal linear polarizations can be generated via asymmetric triangular modulation of period of a few nanoseconds, with a slow rising ramp followed by a fast decreasing one. For an optimal modulation asymmetry the effective threshold reduction is about 20%, the pulse amplitude is maximum and the dispersion of the pulse amplitude is minimum.
Zamora-Munt
J
J
Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Colom 11, E-08222 Terrassa, Barcelona, Spain. jordi.zamora.munt@upc.edu
Masoller
C
C