Detecting weak interferograms by noise dithering

Abstract

Detection of weak interferograms is demonstrated by dithering the subthreshold signal with an optical noise source. The interferogram is produced from a Michelson interferometer and is weakened using a neutral-density-filter (NDF). The optical noise dither is provided by the random fluctuations of the light emitting diode (LED). Detection performance is measured from the signal-to-noise ratio (SNR) of the detected signal. Numerical simulations were also performed for comparison. In both experiments, the improvement in the detection is found to be modulated by the strength of the noise ó. This behavior is similar to that observed in many nonlinear systems exhibiting the stochastic resonance (SR) effect.