The intensity correlation functions C(t) for the colored-gain-noise model of dye lasers are analyzed and compared with those for the loss-noise model. For correlation times~larger than the deterministic relaxation time td, we show with the use of the adiabatic approximation that C(t ) values coincide for both models. For small correlation times we use a method that provides explicit expressions of non-Markovian correlation functions, approximating simultaneously shortand long-time behaviors. Cornparison with numerical simulations shows excellent results simultaneously for shortand long-time regimes. It is found that, when the correlation time of the noise increases, difFerences between the gainand loss-noise models tend to disappear. The decay of C(t ) for both models can be described by a time scale that approaches the deterministic relaxation time. However, in contrast with the loss-noise model, a secondary time scale remains for large times for the gain-noise model, which could allow one to distinguish between both models.

No abstract

A theoretical study of the effect of optical injection on the characteristics of pulses generated by gain-switched single and multimode VCSELs is performed. It is shown that a jitter reduction greater than 50% can be obtained with a slight increase in pulse width. Similar results are obtained for single and multimode emission when the light is injected in the dominant mode.

No abstract

We report an experimental and theoretical investigation of the effect of optical injection on the characteristics of optical pulses generated by gain-switching a 1550 nm single transverse mode vertical-cavity surface-emitting laser (VCSEL). Under continuous wave operation the VCSEL emits in a linear polarization along the whole current range. The experimental analysis of the effect of external optical injection on the timing jitter, maximum power, and pulse width of optical pulses generated by gain-switching the single mode VCSEL is performed for several repetition rates and for different values of the detuning between the frequency of the optical injection and the VCSEL. Experimental results show that for 1 GHz repetition frequency, jitter reductions greater than 70 % can be obtained over a 47 GHz frequency detuning range with a slight increase of 22% in pulse width with respect to the solitary case. A clear anticorrelation between the maximum power and pulse width is also obtained. A theoretical study is also performed by using a model that incorporates both spatial dependence of carrier density and optical field profiles. The two polarization modes are also taken into account in the model. The theoretical results are in good agreement with the experimental results.

No abstract

No abstract

The definition and some general properties of the generalized Weyl correspondence between stochastic processes and operator-valued real functions on a Hilbert space plus a trace class operator are given. The relation between the derivatives of an operator-valued function and the derivative of the corresponding stochastic process are studied. When the operator-valued function is the position (or momentum) in the Heisenberg picture, a condition for the positivity of the joint distribution functions of the corresponding process is given, provided that the evolution Hamiltonian be quadratic in the position and momentum. Finally, the case of an arbitrary Hamiltonian evolution for the position operator is studied and the two-dimensional density functions of the process is related to the Wigner function associated to some state p, and a necessary condition for the positivity of the densities is given.