Influence of higher harmonics on Poincare maps derived from current self-oscillations in a semiconductor superlattice

The effect of higher harmonics on the shape of Poincare maps (first return maps) derived from current self-oscillations has been investigated in a sem iconductor superlattice system driven by a de + ac voltage bias. In additio n to the intrinsic fundamental frequency, a number of higher harmonics with comparable amplitude are observed. The current oscillation traces are simu lated according to the power spectra in order to determine the effect of th e higher harmonics on the Poincare maps. The calculated Poincare maps for q uasiperiodic oscillations as well as frequency locking are clearly distorte d by the presence of the higher harmonics. The shape of the distorted Poinc are maps agrees with the experimentally observed ones. The calculation also reveals that the phase shift between the different frequency components of the current has an important effect on the shape of the Poincare maps. [S0 163-1829(98)03843-0].