Periodically poled lithium niobate second-harmonic optical thresholder for ultrashort pulse optical code division multiple-access

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Abstract
Summary form only given. Ultrashort pulse optical code-division multiple access (CDMA) systems have drawn increasing interest in the past few years, and related technologies such as optical encoding/decoding of ultrashort pulses have been demonstrated by several schemes. However, in order to realize multiplexing and demultiplexing for more than single channel operation, a nonlinear element (e.g., an optical thresholder) is needed to distinguish between correctly decoded signals and incorrectly decoded multi-access interference. Though various thresholder schemes have been proposed, so far none has been able to meet the requirements of high contrast ratio, low operating power, and high detection efficiency set by real-world systems. We demonstrate a novel nonlinear detection scheme for all-optical recognition of spectrally phase coded optical pulses with /spl sim/30 dB contrast ratio and a potential for realizing high conversion efficiencies at an operating power level compatible with current fiber-optic technologies.