Abstract
We propose a novel all-optical wavelength converter based on directionally coupled (DC) semiconductor optical amplifiers (SOA) and simulate its characteristics using a simple model to find out such advantages as extinction enhancement and digital response. We then fabricate devices in the 1.55 /spl mu/m band, and successfully demonstrate the wavelength conversion operation with the above-mentioned advantages. Very compact size and no need of active/passive integration are other significant merits of DC SOA's.