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European Doctorate in Indium Phosphide PIC Fabrication Technology

Periodic Reporting for period 1 - EDIFY (European Doctorate in Indium Phosphide PIC Fabrication Technology)

Reporting period: 2018-10-01 to 2020-09-30

Photonic integration enables multiple optical functions to be delivered on a single chip, a photonic integrated circuit (PIC). Photonic integration also has a dramatic impact on footprint, enabling the miniaturization of optical devices, Power consumption is also reduced and equipment failures are also reduced as these coupling optics are eliminated as a source of failure. Photonic integration is then emerging as a new standard for providing cost effective, high-performance, miniaturised optical systems for a wide range of applications.
However, the complete unfold of PIC potential is still dependent on overcoming certain challenges. Current Indium Phosphide-based PICs (InP PIC) laser sources have phosphorus based active material limiting their operation temperature, thus greatly reducing its potential for low-power operation. Moreover, the overall waveguide losses can be highly reduced by applying the doping only when they are strictly required. A third barrier is the lack of predictive analytical models and design methodologies via the Process Design Kit (PDK) product development software platform. In order to overcome these barriers there is a strong need for researchers with multidisciplinary knowledge of photonics fundamentals, circuit design, dedicated design software and nano-fabrication modalities. The EDIFY project fills these gaps by combining into one training programme a selection of the above-mentioned photonic academic modalities with its direct translation into improvements across the PIC market value chain.
The overall objective of the project is to provide specialised and highly qualified training to a group of Early Stage Researchers (ESRs). The 4 recruited fellows will focus their R&D effort around four Work Packages assigned to one of the recruited ESRs, of 1) Integration of aluminium containing quantum wells, 2) development of low loss waveguides and 3) development of compact models for the next generation photonic design kits and 4) designing PICs which employs the achievements from the previous work packages.
The project outputs are expected to provide a set of new material building blocks and compact models for the InP PDK which will allow for significant improvements in the performance, power consumption and predictive methodologies of current PICs technologies. At the end of the training ESRs will be equipped with a unique set of capabilities that will extend their career possibilities, from the development of predictive software models to complex fabrication technologies always oriented to the needs for the application and end-user requirements. EDIFY consortium covers the whole value chain, from research and design to manufacturing, thereby forming a strong interdisciplinary network between technical sciences and industry to overcome specific barriers in the integrated photonics sector.
The Work Packages (WPs), despite the pandemia, have followed the planned chronogram for ESR1, 2 and 4. They worked completely from home due to the lockdown. Although in terms of theoretical research the project didn´t suffer changes, there was a delay in the cleanroom access in SMART Photonics, due to strict measures to avoid spread. This has affected fabrication, characterization and testing tasks. However, ESRs were ahead of their timelines before the lockdown and fortunately both circumstances balanced the situation. On the other hand, ESR3 entered into the project in July. substituting a former ESR that left the project in March. In this circumstance, there is a significant delay in his chronogram, that will be rescaled to match expected results.
The work performed so far is described for each ESR and respective Work Packages:
ESR1 (WP2): This work focuses on the development of new models. These models are used by both designers and foundries to predict the behaviour of different components on a PIC.
The following tasks have been completed: Analysis and characterization of waveguides from existing experimental results, followed by the development of a predictive model for waveguide performance; Simulation of process fabrication variations on Distributed Bragg Reflector (DBR) gratings; Simulation of a Semiconductor Optical Amplifier (SOA).
ESR2 (WP3): In this Work Package a new technique that will produce a new generation of waveguides characterized by extremely low losses (0.5 dB/cm) is being defined. So far, the following tasks have been finished: Review of past solutions implemented to reduce losses in InP; Simulations of performances of passives and active devices; Chip design to measure losses in waveguides.
ESR3 (WP4): In this Work Package, we pursue the development of Aluminium containing Quantum Well devices in a generic InP-based process. Tasks completed so far are the following: Review of the state-or-the art on semiconductor band gap effects and impact of introducing Aluminium in the layer stack; Review and selecion of techniques to simulate AlInGaAs quantum wells.
ESR4 (WP5): The objectives in this work are the following: The development of application oriented PICs using the new compact models obtained in the other three Work Packages. The following tasks have been completed: The development of a waveguide mode-solver and a test circuit for multimode interferometers; Preliminary design considerations for a coherent communication optical transmitter satellite communications chip.
Finally, we must mention that we have set up and installed a RF and optical measurement probe station laboratory that will allow the ESRs to characterize the chips they will design and fabricate. This lab has received the name of Quantum, cOmmunication and PHotonic Integration Lab. Three servers that accomodate different simulation and design software licenses havev also been installed.
From the expected outcomes of EDIFY, new advances over the existing state of the art will be obtained in the InP integrated photonics fabrication process. This will produce significant advances in the photonic ecosystem. Between them the most important are a) a breakthrough improvement in performance, power consumption and predictive methodologies for photonic Integrated Circuits with direct impact on: data communication, fibre-to-the-home, fibre sensors, gas sensing, medical diagnostics, metrology and consumer products and b) a cohort of ESRs trained on cutting-edge photonic integration and nanofabrication technology, that will directly fuel emerging PIC-based innovation and so ensure the generic foundry scale-up and exploitation by the photonic industry. A number of these PhD designs will surely lead to commercial products or start-ups ensuring translation of state-of-the-art results into exploitable solutions
The achievement of objectives and exploitation of the developed methods, models and tools will not only have an high impact on the partners of EDIFY but also, and more drastically, contribute to boost the global competitiveness of the European photonic foundry ecosystem and related sectors, to create new economic opportunities and jobs. EDIFY is expected to have considerable direct economic impact in several market segments, ranging from telecommunications to novel mixed-reality applications.
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