An Electronic Control Architecture for a Photonic Integrated Circuit

Quantum computing is rapidly growing as well as the interest in it, not only by the scientific community but also by impacting realities such as IBM and Microsoft, which are aiming to be the first to acquire quantum supremacy, a meaningful theoretical step in quantum research where a quantum computer would win undisputed once and for all the race with traditional supercomputers. One of the main enabling technologies for quantum computing is photonics, that features photons as the quantum actors "interacting" in a PIC, mostly based on the mature silicon technology of electronics. This thesis presents my work on electronic control architecture for PICs. The work is based on PICs fabricated in Fondazione Bruno Kessler (FBK) with silicon and dielectric technology, using silicon oxynitride (SiON) as the wave-guiding dielectric medium. The PIC were integrated on Printed Circuit Boards through wire-bonding technique, realizing modules easily integrated and re-configured with the custom made interposer board and the multiple voltage drivers that are at the core of the electronic architecture. Then, both the thermistors and the photodiodes were characterized. A custom firmware was then developed to control the thermistors by providing an analog voltage in the 0-12 V range, and each of those elements effectively acts as a Degree of Freedom (DoF) for the photonic architecture. In addition, to validate the results obtained by voltage driving the phase-shifters, the theoretical output of a single Mach Zehnder Interferometer (MZI) was computed and compared to the one achieved experimentally. Furthermore, such systems are controlled in a closed loop by using as a feedback the photocurrent produced by photodiodes placed either on each output of the PIC or homogeneously integrated withing the PIC itself. Finally, a secondary source of feedback was developed and investigated. Although it is a feasible method to estimate the light intensities of outputs, basing the feedback on invasive sensors implies strict bindings during the design stage and limits the measurable scenarios of a PIC, thus in this thesis I also propose an optical tool to arbitrary tune and control a PIC based solely on camera inspection. By using such technique it would be possible not only to achieve comparable results with respect to the traditional invasive sensing, but also to inspect the system configuration in any section of the chip, without being limited to only the regions where photodiodes would be present.