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3D Photonic integration platform based on multilayer PolyBoard and TriPleX technology for optical switching and remote sensing and ranging applications

Periodic Reporting for period 2 - 3PEAT (3D Photonic integration platform based on multilayer PolyBoard and TriPleX technology for optical switching and remote sensing and ranging applications)

Reporting period: 2019-07-01 to 2022-01-31

3PEAT is unique in the way it effectuates the development of a hybrid photonic integration platform with ultra-high potential in terms of scale and density of integration, and in terms of range and quality of supported functionalities.
The project invests on the combination of two passive photonic integration platforms (the PolyBoard and the TriPleX), each with an already broad toolbox and validated potential to serve as the basis of sophisticated PICs for switching and sensing applications. 3PEAT followed an approach motivated both by innovations at the photonic integration level and opportunities from the market side.

The accomplishment of 3PEAT’s vision was based on the implementation of the following technological objectives:
1) the development of a 3D photonic integration platform based on PolyBoard technology, enabling a disruptive jump in the integration density and the range of supported functionalities on-chip,
2) the establishment of a photonic integration technology for switching applications based on the stress-optic effect on TriPleX platform, enabling a disruptive combination of high switching speed and large number of ports in optical switches,
3) the combination of PolyBoard and TriPleX technologies and the development of a hybrid integration platform with interconnected sections on a single die,
4) the use of this hybrid platform for the fabrication of very large scale photonic integrated circuits with unique complexity and optical functionality and
5) the use of these circuits as the basis for high performance modules in applications spanning a broad range from optical data switching to remote sensing and ranging.

In conclusion, at the end of its contractual lifetime, 3PEAT managed to:
i. develop a disruptive PIC technology with all performance, manufacturability and cost credentials over competing solutions for a very broad range of applications, including optical switching and remote sensing
ii. addressed a number of established and emerging markets, where the need for PICs with high integration density, multifunctionality, reconfiguration speed, low power consumption and low cost are for granted
iii. evaluate its technology in representative settings and to bring the foreground knowledge and the prototypes that will be developed out to the market following consistent exploitation plans
iv. develop and demonstrate at component-level the following components:
− Integrated laser with ultra low linewidth (<100 Hz)
− Laser with integrated isolator as stand alone device
− PZT actuators operating up to 10 MHz
− Integrated optical isolator with exceptional performance in terms of optical isolation ratio
− Integrated optical circulator with high isolation ration and low insertion losses
− Optical FlexLines for PIC interconnection
− Vertical MMIs for enabling the light transmittion between the different waveguide layers
− 2D Optical phased array structures for realizing beam steering without any mechanical parts
− assembly and packaging approaches
− the necessary control electronic units for controlling large scale circuits in different frequency ranges from DC up to MHz regime
During Period 1 the component’s specifications for 3PEAT switching Module-1 and sensing Module-4 and their associated optical and electrical interfaces were defined, which led to the definition of the assembly and the packaging methodologies and to the development of the corresponding testbeds and experimental setups.

Significant progress was achieved in the system design and the methodologies for integration and packaging processes. The application scenario and the datacenter architectures and the system level simulations for the 3PEAT switching and LDV modules have been specified and defined. Moreover, all the specifications and the interfaces between the 3PEAT modules have been defined which lead to the fact that the packaging methodologies with emphasis on the heterogeneous integration of the two TriPleX and PolyBoard platforms have been also defined. Furthermore, the calibration, the operation and the configurations algorithms for the 3PEAT modules have been created as well as the testbeds for the evaluation of Module-1 and 4 including very accurate, sensitive efficient electronics (drivers and PCBs).

Within Period 2, further optimization steps have been achieved for the components in both platforms, which led to PICs with high efficiency. Based on the characterization results of Module-1 and -4, the specification of all the 3PEAT components have been defined and the different PICs have been designed and fabricated. Optical phased array structures has been also fabricated and successfully tested, resulting a very good agreement with the theoretical studies. Moreover, compex electronic control units have been developed, enabling the operation of PICs with high number of active elements. At the end, all the 3PEAT targets have been achieved and the demonstrators have been tested both in lab and quasi-real settings with the participation of the end-users.

Exploitation plans were generated, and dissemination actions were performed aiming to spread the word for 3PEAT. Main channels were talks, twenty one (21) publications, the project website, and project accounts in almost all the social media. Six (6) invited conference talks at high profile conferences presented 3PEAT concept and results. IPR in relevant topics were tracked and evaluated, and four (4) patents were filed by the consortium.
3PEAT’s industry-driven consortium expands along the entire value chain and aims to foster the project’s carefully selected set of innovations into tangible market outcomes. Driven by user needs, the project achieved to bridge innovative research in optical switching and optical sensing with near-market exploitation, achieving transformational impact in energy consumption, compactness and cost.

In the components level progress, within 3PEAT, waveguide structures and couplers have been optimized enabling the very low-loss 3D integration between the TriPleX and the PolyBoard platform. Remaining in the TriPleX platform, different versions of 2- and 3- MRR-based have been developed, with linewidth down to 40 Hz and a tuning range of 80 nm. On PolyBoard platform, an integrated isolator has been developed with optical isolation over 40 dB at 1550 nm and over 32 for a span of 100 nm, performance that is a world best one. The combination of these two photonic circuits by 2D integration, realizes a very novel, stand alone laser source. Different combinations of the integrated optical isolator, can provide the integrated optical circulator, which has also been developed within 3PEAT. Moreover, in PolyBoard platform, a key photonic component has been developed, the vertical multimode interference coupler (vMMI). The exceptional performance in terms of on-chip losses (0.8 dB), enables the light transition between different waveguide layers, realizing a fully functional multilayer PIC. Furthermore, again in PolyBoard platform, the Optical FlexLines have been developed, with low additional losses, enabling the interconnection of different PICs, and thus leading to large scale designs.
Figure 3 Hybrid laser with integrated optical isolator.
Figure 1. Packaged active optical switch.
Figure 5. Hybrid PIC, based on 3D integration between the TriPleX and the PolyBoard platform.
Figure 4. Fabricated integrated optical circulator with high isolation ratio.
Figure 2. Optical FlexLines which enable the interconnection of different PICs.