Photonic multiwavelength transmitters for optical access networks

Indium phosphide (InP)-based photonic integration platforms are nowadays one of the most promising for realization of functionally advanced and compact optical circuits, allowing for light generation, amplification, detection and fast modulation. By making use of these platforms and following the generic technology concept we developed multiwavelength transmitters for application in future optical access networks. The presented devices were fabricated via multi-project wafer runs by an industrial foundry. The size of the fabricated chips is only a few mm2. To design our photonic integrated circuits we took advantage of standardized and parameterized photonic building blocks, such as: passive waveguide devices, semiconductor optical amplifiers, electro-optical phase modulators and distributed Bragg reflector gratings. Our multiwavelength sources used arrayed waveguide gratings as multiplexers of optical signals and as intra-cavity filters within lasers. The designed sources were monolithically integrated with electro-optical modulators in a Mach-Zehnder configuration, for formation of downstream data. We present the photonic multiwavelength transmitters in 4- and 8-channel configurations. The devices allow to simultaneously produce both continuous wave pilot tones that act as a carrier for the upstream data and modulated downstream signals, while the modulation speed reached 1.25 Gb/s (GbE) and 12.5 Gb/s (10 GbE) per transmission channel. The developed transmitters operate within the C-band spectral range with optical output power up to 5 dBm in fiber. The generic devices present a good performance and provide high bandwidth with error-free transmission of the generated optical signals in the broadcasting distances up to 50 km