Southampton and Glasgow Universities currently contribute to a project entitled CORNERSTONE which has established a new Silicon Photonics fabrication capability, based on the Silicon-On-Insulator (SOI) platform, for academic researchers in the UK. The project is due to end in December 2019, after which time the CORNERSTONE fabrication capability will be self-sustaining, with users paying for the service. Based upon demand from the UK's premier photonics researchers, this proposal seeks funding to extend the capability that is offered to UK researchers beyond the current SOI platforms, to include emerging Silicon Photonics platforms, together with capabilities facilitating integration of photonic circuits with electronics, lasers and detectors. These emerging platforms enable a multitude of new applications that have emerged over the past several years, some of which are not suitable for the SOI platform, and some of which complement the SOI platform by serving applications at other wavelengths. Southampton, and Glasgow universities will work together to bring the new platforms to a state of readiness to deliver the new functionality via a multi-project-wafer (MPW) mechanism to satisfy significantly increasing demand, and deliver them to UK academic users free of charge (to the user) for the final six months of the project, in order to establish credibility. This will encourage wider usage of world class equipment within the UK, in line with EPSRC policy. We seek funding for 3 PDRAs and 2 technicians across the 2 institutions, over a 2 year period, to facilitate access to a very significant inventory of equipment at these 2 universities, including access to UK's only deep-UV projection lithography capability. During this 2 year period, we will canvas UK demand for the capability to continue to operate as an EPSRC National Research Facility, and if so, to establish a statement of need. We currently have 50 partners/users providing in-kind support to a value of to £1,705,000 and cash to the value of £173,450.

Silicon photonics is the manipulation of light (photons) in silicon-based substrates, analogous to electronics, which is the manipulation of electrons. The development cycle of a silicon photonics device consists of three stages: design, fabrication, and characterisation. Whilst design and characterisation can readily be done by research groups around the country, the fabrication of silicon photonics devices, circuits and systems requires large scale investments and capital equipment such as cleanrooms, lithography, etching equipment etc. Based at the Universities of Southampton and Glasgow, CORNERSTONE 2.5 will provide world-leading fabrication capability to silicon photonics researchers and the wider science community. Whilst silicon photonics is the focus of CORNERSTONE 2.5, it will also support other technologies that utilise similar fabrication processes, such as MEMS or microfluidics, and the integration of light sources with silicon photonics integrated circuits, as well as supporting any research area that requires high-resolution lithography. The new specialised capabilities available to researchers to support emerging applications in silicon photonics are: 1) quantum photonics based on silicon-on-insulator (SOI) wafers; 2) programmable photonics; 3) all-silicon photodetection; 4) high efficiency grating couplers for low energy, power sensitive systems; 5) enhanced sensing platforms; and 6) light source integration to the silicon nitride platform. Access will be facilitated via a multi-project-wafer (MPW) mechanism whereby multiple users' designs will be fabricated in parallel on the same wafer. This is enabled by the 8" wafer-scale processing capability centred around a deep-UV projection lithography scanner installed at the University of Southampton. The value of CORNERSTONE 2.5 to researchers who wish to use it is enhanced by a network of supporting companies, each providing significant expertise and added value to users. Supporting companies include process-design-kit (PDK) software specialists (Luceda Photonics), reticle suppliers (Compugraphics, Photronics), packaging facilities (Tyndall National Institute, Bay Photonics, Alter Technologies), a mass production silicon photonics foundry (CompoundTek), an epitaxy partner for germanium-on-silicon growth (IQE), fabrication processing support (Oxford Instruments), an MPW broker (EUROPRACTICE), a III-V die supplier (Sivers Semiconductors) and promotion and outreach partners (Photonics Leadership Group, EPIC, CSA Catapult, CPI, Anchored In). Access to the new capabilities will be free-of-charge to UK academics in months 13-18 of the project, and 75% subsidised by the grant in months 19-24. During the 2-year project, we will also canvas UK demand for the capability to continue to operate as an EPSRC National Research Facility, and if so, to establish a Statement of Need.

Within this project we will carry out theoretical and experimental studies of novel types of compact THz sources where semiconductor laser diodes will be combined with a novel dipole/spiral and waveguide photoconductor devices. Specifically, we propose to design, fabricate and assess the performance of the material systems of amorphous/nanocrystalline silicon and quantum-dot semiconductors as materials having short electron-hole photocarrier lifetimes and high photosensitivity at 780-1300nm. In addition to fully characterising and optimising the dual- and multi-longitudinal modes diode lasers we will evaluate the performance of these lasers in the optical pumping of the dipole/spiral and waveguided antennae for obtaining THz power levels in the >100 microwatts range with optimised beam characteristics. The overall objective of this work is to produce a diode-laser-driven, ultra-compact THz source having some potential for additional functionality through its frequency tunability.