FABRICATION OF PRECISION FIBEROPTIC TIME DELAYS WITH IN-SITU MONITORING FOR SUBPICOSECOND ACCURACY

We have developed a technique to produce precise fiber-optic time dela ys with subpicosecond accuracy and <0.1-dB loss by heating and stretch ing optical fiber in a fusion splicer. A fiber Mach-Zehnder interferom eter allows in situ measurement of these precise delays using a simple alignment process and requiring only a weak optical signal. To demons trate this capability, we assembled a six-stage feedforward delay line that can be used to generate 64 optical pulses with 9.5 +/- 0.8-ps pu lse spacings and 4.8-dB total insertion loss. (C) 1997 Optical Society of America.