In this project the design, fabrication and test of an on-chip optical beam forming network (OBFN) will be carried out. The chip would be part of a multiple beam former, i.e., a photonic microsystem which will be applied in phased array antennas for satellites, aircraft and terrestrial 5G base stations. The OBFN will be of the Blass matrix type with 144 antenna ports and 36 beam ports. The OBFN chip will contain tunable Optical Ring Resonators (ORR) which act as true time delays (TTD) and enable broadband beamforming and multiple-beaming. In perspective, the optical chip will be integrated with InP lasers for converting the receiving antenna signals into optical beams as input to the OBFN and InP photodetectors to convert the OBFN output optical signals into RF driving signals for the transmitting antennas. In this project, the use of liquid crystal (LC) technology for tuning of the ORRs will be researched for the first time, to replace conventional thermo-optic tuning based on heaters which cause high dissipation and thermal crosstalk. A significant innovation of this project is related to the power dissipation of the OBFN which will be reduced by 99%. The chip designed by the proponent group will be manufactured by the photonic foundry LioniX Int. BV (NL), in TriPleX (Si3N4/SiO2) technology in the frame of an European collaboration. TriPleX technology based integrated optical waveguides, which is CMOS (Complementary Metal Oxide Semiconductor) compatible, and that will be used to make the ORR have extremely low propagation losses (
The optical beamforming chip that will be developed in this project will be applied in phased array antennas for satellites, aircraft and terrestrial 5G base stations. The beamforming chip contains Optical Ring Resonators (ORR) which act as true time delays enabling broadband beamforming and multiple-beaming. The tuning of the ORRs is usually carried out by thermal heaters, which cause high dissipation and thermal crosstalk. In this project the use of LC technology for tuning of the ORRs will be researched for the first time.
Microwave photonics is an emerging field in which the radio signals are generated, distributed, processed and analyzed using the strength of photonics. It is a disruptive technology which enables various functionalities which are not feasible in the microwave or electronic domain. It also enables new approaches for information and communication systems and networks thanks to the recent rise of PICs (photonic integrated circuits) on both III-V materials and on silicon.
The results of this project will significantly contribute to develop integration of multiple optical components into one higher level assembly which represents the state of the art in the field of photonic integration, microwave photonics and satellite beamforming systems: an optical beamformer. The components that will be integrated are:
Laser,
Optical modulator (array),
Beamforming chip
Optical detector (array)
TriPleX (Si3N4/SiO2) optical waveguide technology will be used in this project for the first time in combination with LC as the enabling technology for high performance integrated microwave photonic systems for phased-array antennas. The key features of this planar waveguide technology are extremely low propagation losses (
Another significant innovation of this project is related to the power dissipation of the OBFN which will be reduced by 99% with respect to the actual state of the art, by exploiting LC tuning for the ORRs of the OBFN, instead of using thermal heaters for the tuning. The dissipation of the beamforming network will reduce from (the unusable) 2 kW, achieved with thermo-optic tuning, to 10 W, which should be obtained with LC.
The heterogeneous integration of these totally different materials, such as LC and Si3N4/SiO2, poses innovative technological challenges in this project which, if successful, will bring a great advantage in terms of strong reduction of heat dissipation and significant reduction of power consumption due to the capacitive nature of the novel tuning technology. Although the OBFN chip developed in this project is aimed mainly to communication satellites, this specific application is intended only as a testbed application. In fact, the hybrid photonic integration technology approach of this project able to produce PIC's with low power dissipation and high performance characteristics can be applied for other application fields such as sensing, datacom optical interconnections and so on. Moreover OBFN for Ka-band Satcom with 144 antenna inputs and capable to process 36 independent beam directions will be realized. A reconfigurable beamforming network with these amount of in- and outputs has never been realized before.
References
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