Field-Programmable Photonic Array for multipurpose microwave photonic applications Daniel Pérez López Universitat Politècncia de València, iPronics Valencia, Spain dperez@iteam.upv.es Aitor López Hernández Universitat Politècncia de València Valencia, Spain ailoher@iteam.upv.es Prometheus DasMahapatra Universitat Politècncia de València, iPronics Valencia, Spain prometheus@iteam.upv.es José Capmany Universitat Politècncia de València, iPronics Valencia, Spain jcapmany@iteam.upv.es Abstract— Software-defined Programmable Photonic ICs enable the dynamic configuration of their internal building blocks to realize the desired circuit. In this paper, we introduce basic and complex software algorithms to achieve multipurpose applications with a special focus on microwave photonics and report the experimental reconfigurations of the optical core for filtering and power splitting applications. Keywords— programmable photonics, integrated optics, signal processing I. INTRODUCTION A. Field-Programmable Photonic Gate Arrays (FPPGAs) Recent advances in Photonic Integrated Circuits (PIC) have focused on the realization of high density, low loss and potentially low power consumption components and circuits and to a lesser degree, on multi-purpose circuits. The primary emphasis has historically rested on the research, development and utilization of Application Specific Photonic Integrated Circuits (ASPICs). Designs such as these are based on optimization of parameters such as performance, optical power budget, electrical power consumption and footprint [1]. However, in regard to the development of ASPICs for low and moderate volumes, the multiple time-consuming cycles of custom design, fabrication, packaging, testing and their associated non-recurring costs involved in the development phase alone imply that they are far from being cost-effective for low to moderate volume fabrication[2]. The evolution of purely electronic circuits had undergone a phase as a result of which, majority of the realization of large volume demands of particular circuits were dealt with using Application Specific Integrated Circuits (ASICs), whereas low to moderate volume demands were tackled by the generic hardware platform of Field Programmable Gated Arrays (FPGAs). An extension of this analogy into the realms of PICs has resulted in the development of multipurpose programmable circuits and field programmable photonic arrays (FPPAs)[3-6] by virtue of which, a single generic PIC hardware made out of electro-optic actuators viz. tunable couplers and phase shifters along with high performance building blocks can cater to the demands of many, at a cost- effective rate and in the form of ready-to-use programmable solutions [3]. A fully software-controlled environment enables user-defined programming and reprogramming and permits the use of such chips across a multitude of platforms while performing as desired. B. FPPGAs in Microwave Photonics Multiple integrated microwave photonic (MWP) applications have been demonstrated relying on a basic set of electro-optical and optical components, [1]. Following the FPPGA rationale, the integration of the most frequently used components in a common hardware platform enables the dynamic programming of multiple MWP applications. As an example, Fig. 1 illustrates a FPPA defined by a 112-Tunable Basic Unit (TBU) optical core and different High- Performance Building Blocks (HPB): optical sources, modulators, photodetectors, delay lines and filters suitable for a wide range of RF-photonics applications. All the elements are connected to the reconfigurable optical core in such a way that, not only do they produce the desired result, they also connect the internal and the external elements required for more complex functionalities. Thus, by tuning each 2x2 TBU or gate, one can route the lightpath and perform dynamic interconnections between the different elements describing a circuit on demand. In this paper, we present basic algorithms enabling the use of FPPGAs for self-characterization and report experimental demonstrations of circuit programming based on presets. II. WORKFLOW AND RESULTS To enable dynamic operation, programmable photonics circuits employ a software framework that aggregates a wide variety of algorithms, methods or routines that are run by an electronic processor unit (PU). In general, this set of algorithms employ input arguments that come from the user settings, the data acquired by the optical power monitors or Fig. 1. Field-Programmable Photonic Array, including a hexagonal reconfigurable optical core and several high-performance building blocks (HPBs).