All-optical burst-mode clock extraction based on the thresholding operation of a modified terahertz optical asymmetric demultiplexer

To implement all-optical burst-mode clock extraction we adopt a modified te rahertz optical asymmetric demultiplexer (MTOAD). The transmittance and ref lectance of the MTOAD depend on the input intensity. For the MTOAD, two lev els of pulse intensity can be chosen in such a way that while the pulses wi th similar intensify are reflected for both strong and weak pulses, only th e strong pulse transmits. The device is useful, for example, for bit-level clock extraction from a packet, where strong and weak intensity pulses are assigned to '1' and '0', respectively. When the input optical signal power is fixed to -1.6 dBm and the intensity ratio between '1' and '0' is varied in the range of 0.2-0.5, the extinction ratio (ER) at the transmitted port is more than 10 dB and a clock amplitude jitter (CAJ) of the bit-level cloc k at the reflected port is less than 14%. Inversely, when the input power i s varied in the range of -6- -1 dBm with fixed intensity ratio of 0.3, more than 11 dB of ER and less than 15% of CAJ are obtained. (C) 1999 Published by Elsevier Science B.V. All rights reserved.