Dynamic gain equalizer using hybrid integrated silica-based planar lightwave circuits with LiNbO/sub 3/ phase shifter array | IEEE Journals & Magazine | IEEE Xplore

Dynamic gain equalizer using hybrid integrated silica-based planar lightwave circuits with LiNbO/sub 3/ phase shifter array


Abstract:

This paper proposes a dynamic gain equalizer (DGE) using hybrid integrated silica-based planar lightwave circuits (PLCs) with a LiNbO/sub 3/ (LN) phase shifter array to a...Show More

Abstract:

This paper proposes a dynamic gain equalizer (DGE) using hybrid integrated silica-based planar lightwave circuits (PLCs) with a LiNbO/sub 3/ (LN) phase shifter array to achieve a DGE that offers both excellent optical performance and control of the phase shifters. The structure consists of two PLCs having arrayed-waveguide gratings (AWGs) and couplers directly attached to the LN phase shifter array at its end faces. To reduce polarization-dependent characteristics, a polarization diversity technique using a polarization beam splitter (PBS) and a circulator was employed. To reduce polarization-dependent loss (PDL) due to the reflected light at the PLC-LN interfaces, tilted waveguides from the normal direction to the interfaces were introduced, and the relation between PDL and power reflectivity was theoretically investigated. A hybrid integrated DGE using super-high-/spl Delta/ PLCs and a 25-channel electrooptic (EO) phase shifter array was demonstrated. The PDL was effectively suppressed with the introduced polarization diversity technique, and the measured spectra were in good agreement with designed profiles. These results indicate that the proposed hybrid integrated DGE offers good performance and controllability for practical applications.
Published in: Journal of Lightwave Technology ( Volume: 24, Issue: 1, January 2006)
Page(s): 495 - 503
Date of Publication: 06 February 2006

ISSN Information:


I. Introduction

The exploding demand for Internet access and broadband services has led to the push for greater lightwave transmission capacity. Wavelength-division-multiplexing (WDM) systems can accommodate the increase in this demand by increasing the number of signal wavelengths propagating on a single fiber. These systems will evolve from point-to-point transmissions to next-generation WDM systems that are incorporated with reconfigurable add/drop nodes. Optical signal power levels in such systems are generally different for every wavelength because of the intrinsically nonflat gain profiles of erbium-doped fiber amplifiers (EDFAs) and the dependence of optical signal levels on network configuration. Since this difference in power levels degrades the signal-to-noise ratio, it is important to keep the levels constant over all channels. Consequently, a dynamic gain equalizer (DGE) is required to automatically compensate for variations in optical signal power levels.

References

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