Silicon and photonics combined
Photonics communications technologies use photons and glass fibres analogously to the way electronic devices use electrons and wires. Although highly successful, the field still faces challenges such as the merger of optical technologies with silicon chips. The EU-funded QUIPS (Quantum ultrafast integrated photonics in silicon) adapted silicon as the material for integrated quantum photonics. The extremely technical work involved developing new sources of photons and ultra-fast optical switches. First, the team developed a design for the optical switch. Results were encouraging, yet the laser facilities available to project researchers initially proved inadequate. The group investigated several solutions, including: use of non-silicon materials, and methods of avoiding or reducing nonlinear losses. Finally, the team chose an alternative means of creating an electro-optical effect, requiring a new process for making barium titanate (BTO). The method was cheap, scalable, and allowed deposition of thin films. Testing of the material proved satisfactory. The group also developed ways of integrating BTO with silicon waveguide and improving the electro-optical coefficient. The method offered a fast and low-loss switching technique that operated at cryogenic temperatures. A later stage involved modifying the design of the system for controlling photons. The team demonstrated the design's viability in the classical optics domain, and in the single photon regime. The research required photons in a single bandwidth, and the work produced a device able to deliver such photons. Demonstrations were underway as of the project's conclusion. Other testing confirmed that the new technologies achieve efficiency of over 90 %. Thus the systems were proven to be robust and suitable for their intended purpose. The QUIPS project successfully merged photonics with conventional silicon circuits. The work attracted considerable attention in the field, and may be a step towards extremely high performance quantum computing.
Keywords
Photonics, silicon chips, QUIPS, quantum, photons, switches
