The comparison of relative intensity noise (Rin) shows improved performances, for quantum dash laser (QD)
compared to the ones of bulk medium structures. We introduced a statistical measurement through a coupling
parameter that reveals the impact of strong damping on the competition between modes or the so-called partition
noise. The existence of a strong damping in QD laser prevents the relaxation frequency from being observed
in the coupling parameter, which makes the noise to appear as if the laser lines were inhomogeneous. However
the method also enables the characterization of the coupling strength between modes, showing again differences
between QD and bulk structures.
We propose in this communication an experimental study of the relaxation oscillations behavior in mode-locked
lasers. The semiconductor self-pulsating laser diode is composed by two gain sections, without saturable absorber.
It is made of bulk structure and designed for optical telecommunication applications. This specific device
allows two different regimes of optical modulation: the first one corresponds to the resonance of the relaxation
oscillations and the second one, to the mode-locking regime at FSR value. This singular behavior leads us to
characterize the self-pulsations which are coexisting in the laser and to describe two regimes of output modulation:
the first one appears thanks to the resonance of the oscillation relaxation and the other one corresponds to the
FSR of the Fabry-Perot laser at 40 GHz.
Ytterbium doped double clad fibers (YDCF) are largely used in the telecom field as high power single mode pump lasers. We present a simple model that permits to describe a double clad pumping scheme. The YDCF is modeled by a sequence of N doped sections. Each section is described by an equation and leads to a set of N coupled equations. It permits to work out the mean fraction of excited ions over each section. The determination of the mean fraction of excited ions is sufficient to evaluate the signal, pump and ASE progress along the fiber. We use this model to calculate the evolution of the amplified spontaneous emission along the fiber, and find out the optimum fiber length for laser operation. We compare this result to experimental results obtained with a homemade fiber.
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