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This paper describes an adaptive dispersion equalizer (ADE) that uses an asynchronous dispersion-induced chirp monitor and the detailed study of the first demonstration of 160-Gb/s adaptive dispersion equalization. The device successfully equalized the dispersion change over a 40°C temperature range (from 5°C to 45°C) and the dispersion slope of an 80-km dispersion-shifted fiber (DSF). The ADE will enhance the feasibility of 160-Gb/s optical transmission systems. [ABSTRACT FROM PUBLISHER]

This paper analyzes in detail numerically a 40-Gb/s return-to-zero (RZ) transmission system over a transoceanic distance in a strongly dispersion managed line composed of standard single-mode fiber (SMF) and dispersion compensation fiber (DCF). We derived a periodically steady-state pulse (a DM soliton) in a DM line. Since the pulse width of a steady-state pulse is too broad for a 40 Gb/s system, the conventional in-line synchronous modulation technique cannot greatly improve the transmission quality. However, we found that the modified inline synchronous modulation technique, which is reported as the black-box optical regenerator, can effectively extend the transmission distance even in such a strongly DM line. We discuss the mechanism of the modified synchronous modulation technique with respect to a steady-state pulse in a transmission line, and show that a 40-Gb/s RZ signal can be transmitted over 20 000 km. [ABSTRACT FROM PUBLISHER]

Step-chirped phase masks for step-chirped fiber Bragg gratings (FBGs) were fabricated by employing a new writing strategy, in which the beam is able to scan a step-chirped pattern all at once or continuously. This new writing strategy was realized by using a raster scan-type laser-beam writing system. Linearly and nonlinearly step-chirped FBGs, fabricated by using these masks, show very low group-delay ripple characteristics, which means that the masks have fewer stitching errors than conventional step-chirped masks [ABSTRACT FROM PUBLISHER]

We realized the first adaptive-dispersion equalizer that equalizes dispersion over a wide wavelength range (6 nm) in the zero-dispersion wavelength region of a dispersion-shifted fiber (DSF). The equalizer is based on a pair of nonlinearly chirped fiber Bragg gratings, which are designed to equalize exactly the dispersion profile of a DSF. The dispersion changes were tracked using a technique that employs opposite dispersion fibers to identify the sign of the dispersion change. Unlike previous approaches, no additional sources or changes in the source wavelength are required. We demonstrate the adaptive equalization of the dispersion changes in an 83-km DSF, induced by temperature changes between -10°C and 60°C [ABSTRACT FROM PUBLISHER]

We realized a wavelength-tunable dispersion equalizer using a pair of nonlinearly chirped fiber Bragg gratings mounted on multilayer piezoelectric transducers. The operation region can be continuously tuned up to 7 nm by applying 50 V. This device enables us to equalize the second- and third-order dispersion of dispersion-shifted fibers with different zero dispersion wavelengths over 6 mn. This performance shows that our equalizer can be employed for adaptive equalization [ABSTRACT FROM PUBLISHER]

The phase errors in electron-beam-written step-chirped masks can be reduced by using a method based on the continuous movement approach and overwriting a pattern at the same place on the substrate several times. The group delay ripple of chirped fiber Bragg gratings fabricated by a four-times-overwritten phase mask is comparable with that of gratings obtained using a holographically written chirped phase mask [ABSTRACT FROM PUBLISHER]

We propose a modified soliton control method for a strongly dispersion managed line, which employs a highly nonlinear fiber in addition to conventional inline synchronous modulation. This method enables us to transmit a 10-Gb/s return-to-zero signal over 20000 km using a dispersion managed line composed of a standard (nondispersion shifted) fiber and dispersion compensation. Optimizing the length of the highly nonlinear fiber greatly increases the power margin of the transmitted optical power [ABSTRACT FROM PUBLISHER]