IN-LINE FIBER OPTIC MEMORY

摘要

IN-LINE FIBER OPTIC MEMORY A fiber optic recirculating memory comprises a splicefree length of optical fiber which forms a loop that is optically closed by means of a fiber optic coupler. The coupler couples an optical signal input pulse to the loop for circulation therein, and outputs a portion of the signal pulse on each circulation to provide a series of output pulses. A pump source is included to pump the fiber loop with a pump signal having sufficient intensity to cause stimulated Raman scattering in the fiber loop, and thereby cause amplification of the circulating signal pulse. The fiber characteristics, coupler characteristics, and pump power are selected to yield a Raman gain which compensates for the total round-trip losses in the fiber loop, so as to provide an output pulse train of constant amplitude pulses. The invention may be implemented utilizing either a standard coupler or a multiplexing coupler. The multiplexing coupler advantageously permits independent selection of the coupling ratios for the pump signal and signal pulse, thereby allowing these coupling ratios to be selected for minimum loop loss and maximum pumping efficiency.