Signal-dependent pump-to-probe noise transfer due to Kerr nonlinearity in silicon ring resonators

Abstract

The pump-probe configuration has been extensively implemented in silicon ring resonators (RRs) for all-optical switching and wavelength conversion. While the pump’s influence on the probe’s signal is well known, the effect of the pump on the probe’s noise has not been studied. Here, we analytically and numerically analyze the impact of the pump’s signal and noise on the probe’s noise distribution. We show that the probe’s output noise has two sources: the probe’s input noise passing through the RR’s transfer function and a new noise term generated by the RR’s transfer function fluctuations caused by the pump’s noise via the Kerr effect. Furthermore, this pump-induced noise can significantly reduce the probe’s output optical signal-to-noise ratio by up to 15 dB. As the new noise term strongly depends on the pump’s power, wavelength conversion of optical communications signals with amplitude modulation formats will result in considerable signal-dependent noise, which can greatly affect the receiver’s design and performance. In addition, the developed probe noise model can be used to design low-noise wavelength converters and switches employing silicon Kerr RRs.