| 摘要 |
A fiber optic recirculating memory comprises a splicefree length of optical fiber (10, 134) which forms a loop (14, 130) that is optically closed by means of a fiber optic coupler (20, 136). The coupler (20, 136) couples an optical signal input pulse to the loop (14, 130) for circulation therein, and outputs a portion of the signal pulse on each circulation to provide a series of output pulses. A pump source (34, 140) is included to pump the fiber loop (14, 130) with a pump signal having sufficient intensity to cause stimulated Raman scattering in the fiber loop (14, 130), 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 roundtrip losses in the fiber loop (14, 130) so as to provide an output pulse train of constant amplitude pulses. The invention may be implemented utilizing a standard coupler (20, 136) with a pump signal modulation technique. The pump signals is input to the loop (14, 130) as a series of pulses having a duration and a periodically chosen to prevent overlap of recirculating pump pulses with input pump pulses until at least two circulations of the loop (14, 130), which minimizes pump power fluctuations and will therefore enhance output signal stability. |
