Fast Detection of a Weak Signal by a Stochastic Resonance Induced by a Coherence Resonance in an Excitable GaAs/Al0.45Ga0.55As Superlattice

Abstract

The effect of a coherence resonance is observed experimentally in a GaAs/Al_{0.45}Ga_{0.55}As superlattice under dc bias at room temperature, which is driven by noise. For an applied voltage, for which no current self-oscillations are observed, regular current self-oscillations with a frequency of about 82 MHz are induced by exceeding a certain noise amplitude. In addition, a novel kind of a stochastic resonance is identified, which is triggered by the coherence resonance. This stochastic resonance appears when the device is driven by an external ac signal with a frequency, which is relatively close to that of the regular current self-oscillations at the coherence resonance. The intrinsic oscillation mode in the coherence resonance is found to be phase locked by an extremely weak ac signal. It is demonstrated that an excitable superlattice device can be used for the fast detection of weak signals submerged in noise. These results are very well reproduced by results using numerical simulations based on a sequential resonant tunneling model of nonlinear electron transport in semiconductor superlattices.

Coherence Resonance and Stochastic Resonance in an Excitable Semiconductor Superlattice

“…4 first decreases from infinity at V rms noise ¼ 1.365 mV and rather more smoothly for V rms noise > 2 mV. This behavior is typical of a CR and agrees qualitatively with the experimental results [25].…”

“…Similar to this numerically demonstrated CR, noise may enhance a weak ac signal, thereby demonstrating a SR. Experiments confirm these predictions [25].…”

“…The corresponding experimental results are presented in Ref. [25]. For a dc voltage bias, when the current drops below a critical value, the external noise may produce large current spikes due to the formation of a CDW at the injector that propagates toward the collector and disappears there.…”

“…These noise values have been selected so that the results of the numerical simulations of the model agree qualitatively with the results of the experiments reported in Refs. [20,25]. We have ignored the smaller value of η th ðtÞ at the SSL wells [21,22].…”

Noise-induced temporal regularity and signal amplification in an optomechanical system with parametric instability

“…Some physical mechanisms allow noise to act beneficially, such as stochastic resonance (SR) [15,16] and coherence resonance (CR) [17][18][19]. As a mechanism for enhancing the response of a nonlinear system to a weak external signal, SR has been observed and investigated in various fields (see review [20]) and used widely to detect [21][22][23], amplify [24,25], and reconstruct [26,27] weak signals. Recently, SR has been introduced in the field of cavity optomechanics, examples being chaos-mediated optomechanical SR [28] and SR in a tristable optomechanical system [8].…”