Frank Bruyere

Key building blocks for high-capacity WDM photonic transport networks

The objective of this paper is to give an overview of the different studies we have performed at the research level regarding the design and implementation of a photonic wavelength division multiplexing (WDM) layer providing transparent transport services to client layers (SONET/SDH, ATM, etc.). Such a network requires a number of enabling factors to be assessed in order to become a reality. Among these factors are the availability of high-capacity WDM transmission systems and efficient optical routing nodes based on mature technology, the design of robust networks optimizing the utilization of resources, and the development of a management system in accordance with presently applied standards for transport networks. We review our achievements in these different fields.

Crosstalk-induced degradation in an optical-noise-limited detection system

Considering an optical-noise-limited detection system, we established theoretically and experimentally that in-band crosstalk tolerance strongly depends on parameters such as optical signal-to-noise ratio extinction ratio and decision threshold.

Gain stabilization of EDFA cascade using clamped-gain SOA

Summary form only given. In wavelength-division multiplexed (WDM) optical networks, channel adding or dropping due to system reconfiguration or faults cause power transients and a residual power change on the surviving channels. Solutions based on the use of an idle channel at the transmitter level to make up for the variations of total optical power have been proposed to combat gain transients. In this paper, we introduce a new compact and reliable all-optical scheme based on a clamped-gain semiconductor amplifier to achieve gain stabilization in a cascade of erbium-doped fiber amplifiers (EDFAs).

Penalties induced by higher-order PMD at 10 Gbit/s in nondispersion-shifted fibers

In a recently published work see, Electron. Lett., vol.31, p.1597, 1995; we have demonstrated theoretically that in nondispersion-shifted fibers, second-order polarization-mode dispersion (PMD) can severely compound the PMD penalty as a result of first-order PMD [i.e., the value of the differential group delay (DGD) at the signal central frequency]. To verify these theoretical results, a l0-Gbit/s nonreturn to zero (NRZ) transmission was set up over a 70 km nondispersion-shifted fiber with a chromatic dispersion near 1550 nm. The l0-Gbit/s transmitter consisted of a modulated DFB laser.