Berlin Access, an initiative of Berlin SMEs and Fraunhofer-HHI for new FTTH technologies

摘要

"Berlin Access", a regional R&D project carried out by six companies and Heinrich Hertz Institute, Fraunhofer Society, is geared towards low cost solutions for fibre access network architectures (PON and CWDM-PON), ONU transceivers, and passive fibre components. Close communication with system manufacturers, non-incumbent carriers, and a city services supplier implementing a local FTTH network supports orientation towards market demands. In this paper we report on a new FTTH transceiver based on an all-polymer PLC motherboard. The waveguides exhibit high transmission, strong optical confinement, and large operation temperature range. Low loss passively adjusted fibre/PLC coupling is achieved by employing a waveguide taper. Downstream/upstream wavelength separation is accomplished by a directional coupler, or, alternatively, a thin film filter inserted into the input/output waveguide (the latter approach also allowing for the provisioning of an overlay broadcasting channel). The horizontal-cavity surface-emitting laser diode, the pin-photodiode (equipped with a thin film filter for improved crosstalk suppression), and the monitor diode are all flip-chip surface mounted; the light being coupled via 45° waveguide mirrors. Chip mounting can be done with a commercial fineplacer using semi-active automatic alignment. Micro-strip lines with impedances adapted to both laser and photodiode are fabricated on the basis of the PLC films. The polymer motherboard integration scheme offers compact transceiver optical subassemblies and lends itself favourably to highly automized, low cost manufacturing with high yield. Extended functionalities like loss of light alarm or concepts for colourless CWDM ONUs can be easily realized with this concept.