The new generation of broadband microwave systems in various fields (wireless communications, satellite communications, sensing, medical imaging) and especially the emerging 5G wireless technology, have very high requirements in terms of carrier frequency, bandwidth, dynamic range, size, power consumption, tunability, and immunity to electromagnetic interference. Moreover, when the microwave signals, that need to be processed, have a very high carrier frequency, the integrated circuits must be able to offer high-bandwidth modulation and detection.
The simultaneous combination of these requirements is very challenging, and the necessary photonic integration technology that could exploit the full potential of MicroWave Photonics (MWP) technology is still missing. HAMLET project came with the mission to contribute technology that exactly fills this gap.
In specific, HAMLET aimed to the development of a powerful photonic integration technology, tailored, for the first time, to the needs of MWP to meet the expectations for commercial uptake with the advent of 5G era. Work carried out by HAMLET was highly based on the heterogeneous integration of graphene sheets on polymer and PZT layers on low-loss Si3N4/SiO2 platforms, in order to develop fast graphene based electro-absorption modulators and an extensive optical beam forming network. To achieve its goals, the project invested on this hybrid technology for the development transceivers that seamlessly interface the optical fronthaul and radio access at the remote antenna units (RAUs) of 5G base stations. For the accomplishment of its mission, HAMLET focused on the following objectives:
- Development of a simple and reliable methodology for integration of graphene on PolyBoard platform for the production of single and arrayed versions (up to 64) of electro-absorption modulators with high bandwidth (>25 GHz) and low insertion loss (<3 dB)
- Development of a simple and reliable methodology for deposition of PZT layers on TriPleX platform for the production of optical phase shifters with sub-μW power consumption and ns response time
- Development of large-scale (up to 1:64) integrated beamforming networks for multi-element antenna arrays based on PZT-based tunable elements on TriPleX platform
- Development of an hybrid integration engine for PolyBoard-to-TriPleX integration with large number (>100) of interconnected waveguides and polymer-to-InP integration with long InP component arrays (up to 64 elements)
- Development of a simple integration engine for integration and co-packaging of optical subassemblies with CMOS electronics and MIMO antennas
- Development of hybrid transceivers with integrated optical and wireless sections for remote antenna units used in future 5G networks operating in the 28 GHz band
- Evaluation of the performance of HAMLET transceivers in emulating 5G system environments in terms of system flexibility and throughput
- Exploration of the full range of potential application domains that can take advantage of and/or benefit from HAMLET technology and preparation of a solid roadmap for its commercial uptake in the post-HAMLET era