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ThFl (Tutorial) 8:30am Passive components for WDM networks Bruce Nyman, JDS Fitel, 15 Meridian Road, Eatontown, New Jersey 07728The development of the erbium-doped fiber amplifier has led to the rapid deployment of wavelength-division multiplexed (WDM) systems. Passive components are used throughout WDM networks. For example, a typical amplifier will contain an isolator, a pump and signal multiplexer, and optical taps. Complete WDM systems require wavelength combiners and demultiplexers. For a DWDM system the demultiplexer represents the state of the art in passive components.In this tutorial, we will discuss the passive components found in a typical WDM system. For each one, device requirements and technology options will be examined. While passive devices may be simple in function, there are many performance issues such as insertion loss, return loss, polarization dependent loss, polarization mode dispersion and chromatic dispersion. Also, all of these characteristics have temperature and wavelength dependencies. For simple components, fabrication techniques include fused fiber and dichroic filter based devices. For demultiplexers, fiber Bragg gratings and waveguide routers must also be considered. In addition, we will note current standards for measurements and reliability.Long-period fiber gratings (LPFGs) are promising components in optical fiber communications. The LPFG is usually fabricated by photo-refractive effect using a UV-laser' or by fiber deformation by local heating method^."^ In this report, we propose a new technique 0.5 -0.4 s = 0.3 v W V Y-$ 2 0.2 W -0 ._ W 0.1 > w m .--2 0.0 ______ before heating -after heating I 0.1%

The nonlinear refractive index coefficient n2 dependence on the GeO, concentration in optical fibers is quantitatively shown for SiO, core fibers and Ge0,-Si02 core/Si02 clad fibers with A = 0.35-2.2% using an XPM measurement method where the phase change in the fiber of a probe signal caused by a pump signal is found from' the delay self-heterodyne spectrum. The GeO, concentration distribution which determines the n2 distribution in the fiber is not uniform, and the measured % is the average of the product of the local n2 and the fourth power of the electric field in the fiber. In this work, this relationship of the measured n,, the cross sectional distribution of %, and the electric field distribution in the fiber is used to define an effective GeO, concentration, qew This effective GeO, concentration level is used to evaluate n2. The measured % increases proportionally to qefi by the relationship %[x 10-20 m2/w1 = 0.0552q,~[mol~] + 2.44.Furthermore, the measured n2 in the fiber agrees well with the of bulk glass obtained a semiempiridy for the nonlinear refractive index coefficient derived from linear refractive index data.