Asymmetry-induced spectral peaks in periodically forced noisy bistable systems

The occurrence of finite-width peaks in the spectral background of a time-sinusoidally forced overdamped bistable Duffing oscillator, subject to a noise-floor, is reported. The peaks, which only occur in the presence of a symmetry-breaking dc signal, are located at approximately the odd integer multiples of the forcing frequency. An analytic expression for the height of the peaks is derived and validated via computer simulations. The peak heights display a non-monotonic dependence on the system asymmetry.