Feedback-measurement-induced anticorrelation between in-loop photocurrent fluctuation and amplifier dark noise

Suppression of in-loop photocurrent fluctuation below the amplifier dark; n oise was observed in both a negative-feedback light-emitting diode (LED) an d a laser diode (LD). We use a new semiclassical model to analyze the squee zed mechanism of the in-loop photocurrent noise mentioned above and find th at there is a feedback-measurement-induced anticorrelation effect between t he measured photocurrent fluctuation and the amplifier dark noise, which re sults in the suppression of the in-loop photocurrent fluctuation below the amplifier dark noise. Our theoretical analysis gives the correlation coeffi cient between the photocurrent fluctuation and amplifier noise, and also yi elds the squeezed spectrum of the in-loop, intensity fluctuation according to our experimental results.