Semiconductor optical digital-to-analogue converter

A semiconductor-integrated optical digital-to-analogue converter, consisting of input and output multimode interference couplers, and one-bit delay line, has been realised for the first time. Small bending curvature owing to the large refractive index difference results in the small size with the delay line of about 1 cm length for 10 Gbit/s optical labels. One-bit delay time of 100 ps for 10 Gbit/s labels, and four-level analogue output signals for two-bit optical labels have been generated.