Recent Progress in InP/Polymer-based Devices for Telecom and Data Center Applications Moritz Kleinert, Ziyang Zhang, David de Felipe, Crispin Zawadzki, Alejandro Maese Novo, Walter Brinker, Martin Möhrle, and Norbert Keil Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, Einsteinufer 37, Berlin 10587, Germany norbert.keil@hhi.fraunhofer.de Abstract: Recent progress on polymer-based photonic devices and hybrid photonic integration technology using InP-based active components is presented. High performance thermo-optic components, including compact polymer variable optical attenuators and switches are powerful tools to regulate and control the light flow in the optical backbone. Polymer arrayed waveguide gratings integrated with InP laser and detector arrays function as low-cost optical line terminals (OLTs) in the WDM-PON network. External cavity tunable lasers combined with C/L band thin- film filter, on-chip U-groove and 45° mirrors construct a compact, bi-directional and color-less optical network unit (ONU). A tunable laser integrated with VOAs, TFEs and two 90° hybrids builds the optical front-end of a colorless, dual-polarization coherent receiver. Multicore polymer waveguides and multi-step 45°mirrors are demonstrated as bridging devices between the spatial- division-multiplexing transmission technology using multi-core fibers and the conventional PLC- based photonic platforms, appealing to the fast development of dense 3D photonic integration. Introduction Highly functional, power efficient and low-cost photonic devices are paving ways for the fast development of the optical communication networks. To combine multiple optical functionalities and provide interfaces with the electronic domain, a generic, flexible integration platform is highly desired. Over the last decade, monolithic integration technologies based on InP material and silicon on insulator (SOI) platform have evolved into large foundry services. However, the service may not always prove to be cost-effective. The complexity in design and fabrication increases almost exponentially with the number of integrated device functionalities. Very often trade-offs in device performance need to be made in order to meet a reasonable yield. On the other hand, the fabrication of single components such as laser diodes (LDs) and photo detectors (PDs) has matured in the last years. As many of the active components are readily available in the market, it makes sense to integrate these components in a hybrid manner onto other motherboard technologies. Recently the polymer-based hybrid integration platform PolyBoard has been established, in which low-loss polymer waveguide components have been developed as well as coupling methods with InP- based active components [1, 2]. Thin-film elements (TFEs) can be inserted for compact and efficient wavelength multiplexing, polarization rotation, splitting and combining. On-chip U-grooves and 45° mirrors allow submount-free and passive attachment of optical fibers and photo detectors. The PolyBoard technology is quickly evolving, tailoring to the various demands of photonic applications. In this work, polymer-based thermo-optic components, U-grooves for fiber-to-chip coupling, and TFE-based polarization handling structures are introduced, followed by the device demonstration for a colorless, dual-polarization 90° hybrid and wavelength-division-multiplexing (WDM) passive optical network (PON) components, including optical line terminals (OLTs) and optical network units (ONUs). In the end, a multicore polymer waveguide platform is introduced, along with the arrayed planar PD attachment method via a series of 45° mirrors. The multicore polymer waveguide platform can provide an intermediate link between multicore fiber (MCF)-based spatial-division-multiplexing (SDM) transmission technology and conventional photonic components based on planar lightwave circuits (PLCs).