T. N. Nielsen

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Experimental results of a wideband heterodyne second-order optical phase-locked loop with 1.5- mu m semiconductor lasers are presented. The loop has a bandwidth of 180 MHz, a gain of 181 dBHz, and a propagation delay of only 400 ps. A beat signal of 8 MHz linewidth is phase locked to become a replica of a microwave reference source close to carrier with a(More)
A tunable dispersion compensating filter based on a multistage optical all-pass filter with a microelectromechanical (MEM) actuated variable reflector and a thermally tuned cavity is described. A two-stage device was demonstrated with a tuning range of /spl plusmn/100 ps/nm, 50-GHz passband and a group delay ripple less than /spl plusmn/3 ps. The device has(More)
We report wavelength-division-multiplexed (WDM) systems experiments with polarization multiplexing at 40 Gb/s per channel and 0.8 bit/s/Hz spectral efficiency designed to explore the worst case impairments caused by first-order polarization-mode dispersion (PMD) in the fiber. Both polarization-division multiplexing using two polarizations at each wavelength(More)
Dispersion management is becoming paramount in high-speed wavelength-division-multiplexed lightwave systems, that operate at per-channel rates of 40 Gb/s and higher. The dispersion tolerances, in these systems, are small enough that sources of dispersion variation, that are negligible in slower systems, become critically important to network performance. At(More)
Single-channel transmission at 320 Gb/s is demonstrated over record length of 200 km of nonzero-dispersion fiber. Typical terrestrial amplifier spacing of 100 km is achieved by using pseudolinear transmission and distributed Raman amplification. Stable semiconductor electroabsorption modulators are used in the transmitter, demultiplexer, and clock recovery,(More)
We demonstrate for the first time a device that enables practical dispersion management of a 160-Gb/s time-division multiplexer system (return-to-zero duty cycle: 30%). The dynamic dispersion is provided by an integrated chirp-tunable Bragg grating which is capable of recovering 2-ps pulses over a tuning range of 50 ps/nm with system power penalty less than(More)
A duobinary transmitter employing two-level electrical drive signals for the modulator, exhibits negligible penalties for transmitting 2/sup 7/-1 as well as 2/sup 31/-1 pseudorandom bit sequences (PRBS's). Previous implementations of duobinary transmitters have relied on driving the modulator with three-level electrical signals, which are very susceptible(More)
An optoelectronic phase-locked loop (PLL) for clock recovery in high-speed optical time-division-multiplexed (OTDM) systems is proposed and experimentally demonstrated. The proposed scheme incorporates a pair of balanced photodetector through which the polarity ambiguity in error signal is resolved, and the cancellation of laser noise enables clock recovery(More)