Alan H. Gnauck

Cancellation of timing and amplitude jitter in symmetric links using highly dispersed pulses

We study the properties of symmetric dispersion compensation in optical links using highly dispersed pulse transmission. We show analytically that by splitting the dispersion compensation equally between the input and output of the link, complete cancellation of the timing and amplitude jitter can be obtained in systems where the power profile is symmetric about the center. We explain the dynamics of this cancellation and show, theoretically and experimentaily, that with practical system parameters, symmetric compensation may lead to a considerable improvement in performance.

40-Gb/s transmission over multiple 120-km spans of conventional single-mode fiber using highly dispersed pulses

We demonstrate the transmission of a 40-Gb/s signal over multiple (up to six) 120-km spans of conventional single-mode fiber (SMF). We use a very low duty cycle return-to-zero (RZ) format which employs optical pulses much shorter than the bit-period. The resulting broad spectrum of these short pulses reduces nonlinear effects and enables the transmission of the signal over long distances.

Bidirectional, subcarrier-multiplexed transmission using 1.3-μm Fabry-Perot lasers

We demonstrate a full-duplex, subcarrier-multiplexed, transmission system which employs 1.3-/spl mu/m Fabry-Perot strained layer MQW laser diode transmitters in both directions. Coherent effects are reduced by using lasers with different mode spacing.

Transmission of M-QAM signals using an unisolated DFB laser

We examine the transmission of M-ary quadrature-amplitude modulated (M-QAM) signals using an unisolated distributed-feedback (DFB) laser. Since forward-error-correction is readily available, it is employed in the experiments. We demonstrate that unisolated DFBs can transmit over 80 64-QAM channels; these could carry 500 compressed video channels.

Providing compressed digital video over mini-fiber nodes

Previously, mini-fiber-node (mFN) technology has been proposed to upgrade existing cable TV (CATV) systems to provide bidirectional, broadband capabilities. In this letter, we describe how the mFNs can be used to provide multiple channels of compressed digital video. This allows cable operators to simultaneously add additional broadcast and narrowcast digital video services and install bidirectional services cost effectively, without affecting existing services.

Highly dispersed pulses for transmission at 40 Gb/s

As the signal-to-noise ratio (SNR) requirement increases, there is a need for higher launched signal power, which can increase signal degradation from fiber nonlinearities, such as self-phase modulation (SPM). However, short pulse RZ offers significant advantages for transmission at 40 Gb/s. The broad spectrum of the short pulses leads to a very short dispersion length in dispersive fibers, such as standard single-mode fibers (SMF) operating around 1550 nm. Because the pulses become highly dispersed, phase-matching of the frequency components in the signal is reduced in the fiber link, which reduces the effects of SPM. Therefore, the launched signal power can be increased to provide sufficient SNR for transmission over many amplified spans. Moreover, once the pulses are dispersed, the location of dispersion compensation is not critical. Therefore, all dispersion compensation can be placed at the end of the transmission link, rather than in the more usual span-by-span configuration. Using these concepts, we demonstrate 40 Gb/s transmission over SMF links up to 800 km.