Abstract

Wavelength shifters allow for dynamic routing and wavelength reuse in wavelength-division-multiplexed (WDM) optical networks and switching systems. Several wavelength shifting schemes have been proposed, including cross-gain modulation, cross-phase modulation, and four-wave-mixing in a semiconductor optical amplifier. The cross-gain modulation method provides high conversion efficiency and a wide shifting range. However, the extinction ratio is significantly degraded upon upshifting. Recently, a two-stage wavelength shifting module by parallel pumping was demonstrated which enhances the extinction ratio[1]. To use the module in WDM-based photonic switching systems, its reversed output waveform should be reversed again by cascading one more wavelength shifter before or after the module (Thus three-stage). This additional stage could degrade the overall extinction ratio. We investigated the extinction ratio performances for three wavelength shifter schemes that employs cross-gain modulation.

© 1998 IEEE