Statistics of the optical intensity of a chaotic external-cavity DFB laser

Abstract

We study experimentally and theoretically the first- and second-order statistics of the optical intensity of a chaotic external-cavity semiconductor DFB laser in fully developed coherence-collapse. The second-order statistic is characterized by the autocorrelation, where we achieve consistent experimental and theoretical results over the entire parameter range considered. For the first-order statistic, we find that the experimental probability-density function is significantly more concentrated around the mean optical power and robust to parameter changes than theory predicts.

Multiscale Ordinal Symbolic Analysis of the Lang-Kobayashi Model for External-Cavity Semiconductor Lasers: A Test of Theory

“…Our comparative PE analysis thus reveals that the LK model does not reproduce perfectly the deterministic evolution of an ECL on short timescales corresponding to a fraction of τ RO . Interestingly, this was not revealed by the (linear) ACV analysis we performed in [14] since the decorrelation time was shown to be well matched in simulation and experiments. Figure 4 shows typical examples of PE at long timescales from the LK model and experiment.…”

“…One is to focus on low-order statistics extracted from I(t), such as autocovariance (ACV) and probability density function (PDF). Recently, we found substantial agreement between theory and experiment for the ACVs with some discrepancies for the PDFs [14]. Such approaches are relatively straightforward, but as mentioned above, provide limited confidence concerning the agreement.…”

“…1 [11]. It consists of an intrinsically single-longitudinal-mode MQW InGaAsP DFB laser, at near 1550 nm wavelength with maximum cw power of 15 mW [14]. The free-running laser threshold current J th is ∼ 9.27 mA.…”

“…The free-running laser threshold current J th is ∼ 9.27 mA. The position of a mirror (M) determines τ S = 2L/c (L =external-cavity length, c =speed of light) with L = 65 cm giving τ S = 4.3 ns; the dimensionless experimental feedback rate η is controlled as described in [14]; when η = 1, ∼ 20% of the optical power is fed back onto the laser diode (LD). J is held well above J th of the solitary LD throughout the experiment.…”

“…Moderate noise (not included) does not significantly change the theoretical dynamics for the values of J considered. In our previous work [14], we estimated a maximum theoretical feedback rate γ = 25 ns −1 , corresponding to η = 1 in our setup. Simulations were conducted with a fourth-order RungeKutta method with a time step of ∆t = 1 ps and random initial conditions.…”