Performance of electronic dispersion compensator for 10Gb/s multimode fiber links

In high-speed optical links, electronic compensation circuits can be utilized to greatly improve the data transmission performance limited by fiber dispersion. In this paper, we develop a full link model, including multimode fibers, optical/electronics/optical components, clock-and-data recovery and electronic compensation circuits. The performance of various electronic compensation techniques, such as feed-forward equalizer and decision feedback equalizer for optical multimode fiber is investigated and numerically evaluated. Finally, a comparison of the performance of each compensation techniques and a proposal of optimal equalizer circuit implementation, achieving a 10-Gb/s transmission over 1-km standard multimode fiber are presented

Electronic equalization for advanced modulation formats in dispersion-limited systems

We investigate in this letter the use of electronic equalization on dispersion limited systems for different modulation formats. Besides analyzing equalization on standard NRZ intensity modulation as a reference, we focus on two advanced modulation formats, Duobinary and Differential Phase Shift Keying (DPSK) which are recently gaining large attention. We demonstrate that the introduction of an electronic equalizer strongly improves standard NRZ performance, whereas it has a limited effect on Duobinary and DPSK formats. Moreover, we give rules for the optimal choice of the equalizer transversal filter parameters, i.e., the number of taps and the delay between taps

Electronic dispersion precompensation of direct-detected NRZ using analog filtering

We demonstrate (in real-time) electrical dispersion compensation in direct detection links using analog transmit side filtering techniques. By this means, we extend the fiber reach using a low complexity solution while avoiding digital preprocessing and digital-to-analog converters (DACs) which are commonly used nowadays. Modulation is done using an IQ MachZehnder modulator (MZM) which allows straightforward compensation of the complex impulse response caused by chromatic dispersion in the fiber. A SiGe BiCMOS 5-tap analog complex finite impulse response (FIR) filter chip and/or a delay between both driving signals of the MZMs is proposed for the filter implementation. Several link experiments are conducted in C-band where transmission up to 60 km of standard single-mode fiber (SSMF) of direct detected 28Gb/s NRZ/OOK is demonstrated. The presented technique can be used in applications where low power consumption is critical

Integrated Transversal Equalizers in High-Speed Fiber-Optic Systems

Intersymbol interference (ISI) caused by intermodal dispersion in multimode fibers is the major limiting factor in the achievable data rate or transmission distance in high-speed multimode fiber-optic links for local area networks applications. Compared with optical-domain and other electrical-domain dispersion compensation methods, equalization with transversal filters based on distributed circuit techniques presents a cost-effective and low-power solution. The design of integrated distributed transversal equalizers is described in detail with focus on delay lines and gain stages. This seven-tap distributed transversal equalizer prototype has been implemented in a commercial 0.18-µm SiGe BiCMOS process for 10-Gb/s multimode fiber-optic links. A seven-tap distributed transversal equalizer reduces the ISI of a 10-Gb/s signal after 800 m of 50-µm multimode fiber from 5 to 1.38 dB, and improves the bit-error rate from about 10^-5 to less than 10^-12