Carrier scattering is known to crucially affect the dynamics of quantum dot (QD) laser devices. We show that the dynamic properties of a QD laser under optical injection are also affected by Coulomb scattering processes and can be optimized by band structure engineering. The nonlinear dynamics of optically injected QD lasers is numerically analyzed as a function of microscopically calculated scattering lifetimes. These lifetimes alter the turn-on damping of the solitary QD laser as well as the complex bifurcation scenarios of the laser under optical injection. Furthermore, we find a pump current sensitivity of the frequency-locking range, which is directly related to the nonlinearity of the carrier lifetimes.
Noise characteristics (optical and electrical fluctuations and cross-correlation factor between two noise signals) of high power nitride-based white light emitting diodes (LEDs) have been investigated for initial samples and after accelerated aging. Different spectrum parts from white LED radiation have been investigated separately. Electrical fluctuations and low frequency optical noise of investigated LEDs distinguish by 1/f α -type spectrum (above 100 Hz shot noise prevails in optical noise). 1/f α -type optical and electrical fluctuations are partly correlated. After accelerated aging optical 1/f α -type noise intensity increased, and cross-correlation factor between blue and red light intensity fluctuation increased, too. Origin of increased 1/f α -type optical noise is defects in the active layer of investigated white LED, and their increase during aging.
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