Realization of a multilayer photonic process, as well as co-integration of a large number of photonic and electronic components on a single substrate, presents many advantages over conventional solutions and opens a pathway for various novel architectures and applications. Despite the many potential advantages, realization of a complex multilayer photonic process compatible with low-cost CMOS platforms remains challenging. In this paper, a photonic platform is investigated that uses subtractively manufactured structures to fabricate such systems. These structures are created solely using simple post-processing methods, with no modification to the foundry process. This method uses the well-controlled metal layers of advanced integrated electronics as sacrificial layers to define dielectric shapes as optical components. Metal patterns are removed using an etching process, leaving behind a complex multilayer photonic system, while keeping the electronics'metal wiring intact. This approach can be applied to any integrated chip with well-defined metallization, including those produced in pure electronics processes, pure photonics processes, heterogeneously integrated processes, monolithic electronic-photonic processes, etc. This paper provides a proof-of-concept example of monolithic electronic-photonic integration in a 65 nm bulk CMOS process and demonstrates proof-of-concept photonic structures. The fabrication results, characterization, and measurement data are presented.
Optical synchronization of large-span arrays offers significant benefits over electrical methods in terms of the weight, cost, power dissipation, and complexity of the clock distribution network. This work presents the analysis and design of the first phased array transmitter synchronized using a fully monolithic CMOS optical receiver. We demonstrate a bulk CMOS, 8-element, 28-GHz phased array building block with an on-chip photodiode (PD) that receives and processes the optical clock and uses an integrated PLL to generate eight independent phase-programmable RF outputs. The system demonstrates beam steering, data transmission, and remote synchronization of array elements at 28 GHz with fiber lengths up to 25 m, in order to show the scaling benefits of our approach. The provision of small footprint and cost-effective CMOS transceivers with integrated optoelectronic receivers enables exciting opportunities for low-cost and ultralight array systems.
A sixteen-element coherent array of wideband spiral antennas driven by photodetectors is presented. The array radiates between 21 and 65 GHz, with -45 dBm of coupled power at 42 GHz.
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