The internet is the force that drives the rapid growth of the optical networks. The drastically increasing traffic pushes developments to higher bit rates, more data channels, and high speed optical signal processing. A second and also very important consequence of the expected dominance of the internet regards the type of traffic. The trend goes from the present synchronous networks to packet switching in future asynchronous networks. This leads to a new challenge: to develop clock recoveries that lock ultrafast to incoming data packets. One attractive target is to combine the ultra-fast locking function with an all-optical clock recovery that has a high speed potential. We develop self-pulsating DFB lasers for optical clock recovery. The good performance of the optical clock in 10 Gb/s synchronous data streams has already been demonstrated. The clock works without penalty compared to a PLL. The BER performance is not affected by the PRBS word length 2~(7)-1 or 2~(31)-1 [1-3]. This demonstrates that sequences of 31 "zero" bits cause no degradation. The clock keeps synchronized even longer, for some hundreds zeroes. This paper focuses on the locking time.
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