# Fully Reconfigurable Photonic Filter for Flexible Payloads
## 1 Introduction  
A satellite consists of two essential components: a bus or platform and a payload. The payload serves as the central element in any space flight mission and its key parameters, including mass, geometry, power requirements, and communication needs, dictate the characteristics of the accompanying satellite platform or bus. In the satellites currently in orbit, photonic components are integrated into several subsystems, such as EO optical payloads, attitude control systems, telecommunication transceivers, and power supply subsystems. Depending on the specific mission application, an optical communications solution has the potential to deliver significant benefits. This includes a 50% reduction in mass, which can lead to cost savings in spacecraft development and potentially provide additional space for more advanced instruments, as well as a 65% reduction in power consumption, thereby extending the mission's operational lifetime [1]. According to NASA's estimations, the transition towards photonics technology could potentially result in a data rate increase of up to 100 times. This advance would significantly enhance data collection capabilities andreduce the complexity of mission operations. It would also address challenges associated with microwave spectral congestion, spectrum allocation, and the limited bandwidth (BW) typically encountered in RF communications. Moreover, the adoption of photonics would open up new possibilities for scientific missions that demand wide bandwidth, such as hyperspectral imaging and instruments offering high-definition capabilities in spectral, spatial, and temporal modes [1]. Currently, the NASA Electronic Parts and Packaging Program (NEPP) is developing a photonics radiation data library and guidelines for apace qualification, and the initial results indicate potential robust radiation hardness of integrated photonics, mainly for SOI- and InP-based technology platforms [2; 3; 4]. Nevertheless, some challenges must be addressed, including a lack of on-orbit reliability and radiation data about the operational lifespan of lasers and optical components and additive optical background noise from sunlight, which imposes limitations on overall performance. In recent years, space communications have shifted from S-band to both X-band and Ka-band, fulfilling the increasing demand for high-volume data returns from scientific missions. According to forecasts, space applications are expected to exceed the capacity available in the RF Ka-band (GHz) range, with a resulting need to transition towards higher bandwidths within the unregulated and unconstrained optical communication spectrum (THz). Optical communications offer advantages in terms of SWaP reduction, including the ability to achieve the same data rates with significantly smaller aperture sizes compared to RF antennas [5]. Enhanced reliability stands as a fundamental objective, aiming to improve both performance and efficiency, with the goal of reducing the overall mission lifecycle cost. Nowadays, research in the field of photonics for space is focused on the development of next-generation optical communication systems. These systems encompass inter-satellite and satellite-to-ground communications, as well as modulators and filters designed to ensure broadband internet connectivity via satellites. The aim is to establish a higher bitrate, with spectrally efficient satellite links, enabling high-speed communications [6]. In anticipation of forthcoming innovative satellite communication ventures, the demand for highly advanced payloads is paramount. These payloads must possess an inherent flexibility that allows for post-launch adaptability and optimization, catering seamlessly to the evolving and diverse requirements of users concerning bandwidth, coverage, and frequency allocation. The dynamism of modern communication needs necessitates a transformative approach, enabling satellites to adjust and fine-tune their functionalities after their deployment in orbit.