Statistics of the transient frequency modulation in the switch-on of a single-mode semiconductor laser (original) (raw)
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Statistics for the transient response of single-mode semiconductor laser gain switching
Physical Review A, 1991
For a gain-switched semiconductor laser we study the statistics of the time at which the laser intensity first reaches a threshold level and also the laser intensity fluctuations in the nonlinear regime. The dispersion in the maximum value of the laser intensity at the first peak of the relaxation oscillations is calculated. A simple relation between this maximum value and the passage time for each individual switch-on event is found.
Photonics
A two-section semiconductor laser can exhibit excitability for certain parameter settings. When used as a photonic spiking neuron, it is relevant to investigate its sensitivity to noise due to, e.g., spontaneous emission. Under excitable conditions, the system emits irregularly timed noise-triggered pulses. Their statistics is analyzed in terms of a first-passage time distribution for the fluctuating intensity to reach the threshold for excitable response. Two analytic approximations valid for short and long times, respectively, are derived which very well explain measured and simulated pulse-repetition time distributions. This provides physical insight into the noise-triggered spiking mechanism.
Physical Review A, 1999
We present detailed statistical investigations of the irregular fast pulsing behavior present in the dynamics of semiconductor lasers with delayed optical feedback operating in the low-frequency fluctuation and coherence collapse regimes. We demonstrate that the probability density distributions of the laser intensity on a picosecond time scale are essentially independent of the number of optical modes involved in the laser emission, using two complementary high-resolution experimental measurement systems: a high-bandwidth sampling digitizer and a single-shot streak camera. The experimental results are supported by numerical studies using the singlemode Lang-Kobayashi equations, as well as a multimode extension of the model. Furthermore, we also demonstrate that gain saturation and coexisting attractors can cause substantial qualitative changes of the probability density distribution.
Pulse statistics in single-mode semiconductor lasers modulated at gigahertz rates
Optics Letters, 1991
The statistics of switch-on time, maximum light intensity, and pulse width of single-mode lasers modulated at gigahertz rates are analyzed. Numerical results obtained from noise-driven rate equations are reported. Pulse statistics, and in particular timing jitter, are shown to be rather insensitive to the bias current at this high-speed modulation. In addition, pulse statistics become rather independent of the modulation period when biasing slightly below threshold.
Physical Review E, 1999
Semiconductor lasers with optical feedback present a regime in which power dropouts are observed. Although this regime has been extensively studied, there is no agreement about whether the dropouts are deterministically or stochastically generated. In this paper we will study the statistics of time intervals between dropouts assuming noise-driven simple excitable models. We explain the appearance of characteristic times in the first return maps. ͓S1063-651X͑99͒00408-0͔
Temporal Dynamics of Semiconductor Lasers with Optical Feedback
Physical Review Letters, 1998
We measure the temporal evolution of the intensity of an edge emitting semiconductor laser with delayed optical feedback for time spans ranging from 4.5 to 65 ns with a time resolution from 16 to 230 ps, respectively. Spectrally resolved streak camera measurements show that the fast pulsing of the total intensity is a consequence of the time delay and multimode operation of the laser. We experimentally observe that the instabilities at low frequency are generated by the interaction among different modes of the laser. [S0031-9007(98)08077-6] PACS numbers: 05.45. + b, 05.40. + j, 42.60.Mi Nonlinear systems with delayed feedback are of interest because they can be widely found in economy, biology, chemistry, and physics [1]. These systems are in principle infinite dimensional, and from this point of view, it is difficult to classify them a priori as deterministic dynamical systems because the existence and uniqueness of a solution have to be demonstrated for each particular model . It is also difficult to separate the role of noise from determinism, because complex solutions display a Gaussian-Markovian behavior as if they were solutions of a Langevin equation , thus nonconventional measurement techniques are required .
Detecting mode hopping in semiconductor lasers by monitoring intensity noise
IEEE Journal of Quantum Electronics, 1993
Mode-hopping semiconductor lasers exhibit intensity fluctuations which are correlated to the level of mode-hopping activity. It is shown that these fluctations occur at a level that is easily measured. A plot of these fluctuations versus laser case temperature and injection current displays periodicities in the conditions under which mode hopping occurs. We explain these regularities in terms of the peak gain wavelength passing the longitudinal mode wavelength as temperature changes. We use the fact that the laser's junction temperature depends on both the case temperature and on the injection current. We note that the onset of mode hopping also depends on the transition from multimode to single-mode operation. Implications for control of mode hopping are discussed.
Intensity and Phase Noise of Semiconductor Lasers Operating in Single Mode
Semiconductor lasers often involve various noise and instability problems due to fluctuation of photon and carrier numbers. In this paper, we analyze the intensity and phase noise of semiconductor lasers operating in single mode. To overcome limitations of the small-signal analysis we use direct numerical integration of the self-consistent rate equations for photon number, phase and carrier density. Langevin noise sources for photon number and phase have been introduced to the rate equations to include fluctuations due to spontaneous emission and the process of carrier recombination. Rate equations are applied to 850-nm GaAs lasers. Fast Fourier Transform (FFT) has been used to calculate the frequency spectra of both intensity and phase noise. Noise characteristics for different injection currents have been demonstrated. Results show that intensity and phase noise decrease with the increase of the injection current density and linewidths were decreasing substantially with increasing injection current as well.