Fiberoptic based recirculating memory loop

Abstract

The authors discuss the design of a low-loss, low-noise figure fiber optic delay element at 1300 nm, capable of recirculating a short electrical pulse as long as a millisecond over the 2-4-GHz frequency band by using an adaptive gain equalizing technique. While the RF pulses are recirculating in the system the noise level starts to build up. By looking at the spectrum of the output signal the effect of the recirculation on the spectral purity of the microwave signals can be studied. The spectral purity characteristics of recirculated signals were quantified for various recirculation times.