Flexible Photonic Integrated Circuits: A New Paradigm to Process Data On-Board Satellites.

Photonic Integrated Circuits (PICs) are becoming an enabling technology suitable for a large range of applications such as Space and biomedicine. PICs deal with light signals exploiting photonic basic building blocks. Their attractiveness is mainly related to the capability to manage analog signals without A/D conversion [1].NewSpace Economy sets several constraints mainly in terms of reliability and flexibility of on-board systems, taking into account the need for small size and low weight, low propagation losses, low power consumption, immunity to electromagnetic disturbances, high processing speed, wide bandwidth, and radiation resistance. Reconfigurable PICs are one of the most promising technologies to fulfil all those requirements. In particular, system flexibility could be achieved by means of programmable or tuneable Application-Specific PICs (ASPICs) [2].A tuneable PIC should be tailored according to the targeted applications. It exploits different physical effects, e.g. thermo-optic effect, electro-optic effect, or phase-changing materials, to optimize its functionalities also reconfiguring itself in relation to the user demands or external environment. The main bottlenecks of this approach are the need for specific design and optimization each time, the recursive designing costs, and the lack of multitasking. On the other hand, a programmable PIC exploits the same chip to perform several functions, even targeted to different applications. Although the latter approach ensures larger flexibility, the main issues are the high power consumption related to the tuning of different elements at the same time, and lower performance than ASPIC (e.g. insertion loss, wavelength precision, limited free spectral range) [3] - [5].Here, both approaches for systems flexibility are carefully reviewed, rating their limits and potential developments, also evaluating the tuning mechanisms and technological challenges. The suitability of the aforementioned systems for Space applications is also critically analysed, aiming at highlighting the main functionalities needed to process data on-board.