In alignment with the objective of SiComb project, three technical work packages have been organized: WP1: silicon carbide on insulator (SiCOI) stacks formation; WP2: SiC nanophotonics devices fabrication and characterization and WP3: SiC optical devices’ system application. These three work packages focuses on material, device and system respectively, with huge interactions among the work packages at the same time. The multidisciplinary nature of SiComb projects has posed challenges for partners with different background to understand each other deeply. One big achievement is that during the project a united consortium is formed after large amounts of meetings and webinars. For WP1, both amorphous SiCOI stacks and 3C-SiCOI stacks have been achieved. The amorphous SiCOI stacks are deposited by both plasma enhanced chemical vapour deposition (PECVD) and physical vapour deposition (PVD), and they are device fabrication ready. Additionally, 3C- SiCOI stacks by direct 3C-SiC growth on SOI (silicon-on-insulator) substrates are successfully demonstrated. For WP2, a standard mask layout and a stable processing flow to evaluate the materials received from WP1 have been established. So far PECVD deposited amorphous SiCOI stacks show the lowest material loss, compared to PVD a-SiCOI and 3C-SiCOI: 5~6dB/cm measured by a retrofitted prism coupler setup. The waveguide propagation loss is about 7~8 dB/cm, derived from the resonance of a microring resonator, which indicated the fabrication introduced extra loss is already as low as about 2dB/cm. Thermal-optical coefficient of amorphous SiCOI was studied and quantified, and a prototype for temperature control is fabricated. Three different types of coupling scheme have been optimized for SiCOI stacks, i.e edge coupler, grating coupler and trident edge coupler. Among them, trident edge coupler shows the highest coupling efficiency. Effort on 4H-SiCOI stacks formation and material loss reduction is also made. Optical frequency comb is demonstrated from 4H-SiCOI which is made by bonding and grinding without implantation step. For WP3, the frequency comb chips are assembled on custom-designed evaluation boards and characterized. The frequency comb subsystem combined with integrated silicon photonic transmitter and receiver chips that were taped out in a commercial multi-project wafer run service is tested.
Sicomb project marks the culmination of our collective efforts to advance the frontiers of integrated photonics and frequency comb technology. Throughout the duration of this project, partners have achieved significant milestones and made substantial progress towards our objectives.
The development of a CMOS-compatible and ultra-broadband on-chip Silicon carbide frequency comb represents a groundbreaking innovation with profound implications for various fields, including telecommunications, sensing, and spectroscopy.
Our dissemination efforts have been aimed at sharing our findings and insights with diverse stakeholders, including academia, industry partners, policymakers, and the broader scientific community. Through webinars, conferences, publications, and workshops, partners have strived to ensure that the knowledge generated through this project reaches audiences worldwide, fostering collaboration and driving further advancements in the field.
Furthermore, our exploitation strategies have been designed to maximise the impact of our results, laying the groundwork for future commercialization, integration into existing technologies, and applications in real-world scenarios. By identifying potential market opportunities, engaging with industry partners, and protecting intellectual property rights, we have paved the way for the translation of research outcomes into tangible societal benefits.
The primarily targeted application of the project is to:
• Use SiC-based frequency combs as a wavelength division multiplexing (WDM) light source
• In datacenter applications
• Enabling very low-energy multi-wavelength transceivers for ultra-big data capacity, with energy-saving potential
This is a rather long-term business opportunity, which would require further material, device and process improvements, and complete validations before an industrially and market viable technological solution would become available.
The primary business case of data centre application is realistic in the mid-to-long term scale, and there is a high potential of creating a significant impact in this area. In addition, the technologies developed during the project allow for exploring new development opportunities and application areas and the consortium is continuously looking for preparing projects on the respective topics.
While the project delivered 2 patent applications, it also generated a broad dissemination portfolio comprising peer-reviewed scientific publications, conferences and workshops, training materials and many others.
