Optical integrated circuits for large-scale quantum networks

• Main Author: Posner, Matthew T.
• Other Authors: Smith, Peter
• Published: University of Southampton 2017
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.736682

This thesis presents the development of a platform to fabricate photonics integrated circuits that can be used to scale networks intended for quantum information processing (QIP) experiments. The stringent technical requirements for the transport and manipulation of quantum states of light are discussed with respect to channel waveguides and integrated gratings fabricated in silica-on-silicon through direct UV writing laser processing Tilted gratings are identified as a method to enable polarisation-based applications for this integrated platform. A novel implementation of in-line planar waveguide polarisers based on 45º tilted gratings is presented, demonstrating gratings with polarisation extinction ratio (PER) of 0.25 dB/mm and bandwidth impairments better than 0.3 dB in the C-band. 45º tilted gratings in UV written waveguides are used to create novel polarising coupler architectures with PER of 28.5 dB. The alteration of the material composition of germanesilicate planar core layers is investigated, producing waveguides with birefringence of 4.5 ± 0.2 × 10−4, higher than previously reported for this platform. A process for producing end facet endcaps to extend the platform’s capability for high power applications is also described. These developments offer potential for the scaling of QIP experiments with heralded spontaneous four-wave mixing single-photon sources. Finally, the thesis describes research-based education experiments conducted to inform a wide range of audiences on the importance of photonics technologies. The concept of Photonics, and the underlying science and associated research, has been introduced to 2,952 students from 81 schools in the South of England and over 6,000people in public events.