FIBER OPTIC DELAY-LINE MEMORY

A model for digital synchronous delay line memory (DSDLM) is given, yielding limitations on the maximum number of bits that can be reliably stored for a given change in delay medium temperature and amount ofmedium dispersion. More than 22 million bits can be stored when single-mode optical fiber is used as themedium, but only if operated at the wavelength of minimum dispersion and by limiting thermal fluctuationsto within 0.002° C. A DSDLM is being constructed using such fiber, along with lithium niobate directionalcouplers as the switching elements. Signal regeneration errors, switch crosstalk, and polarization losses arenegligible for the implementation. With a modulation frequency of 100 MHz, a single-line 2000-bit memorycan be reliably operated without thermal compensation given a temperature fluctuation of <8°C. © 1990 Optical Society of America.