|ZANETTO FRANCESCO||Cycle: XXXIII |
Tutor: FIORINI CARLO ETTORE
Advisor: SAMPIETRO MARCO Major Research topic
:Electronic circuits and systems for photonic applicationsAbstract:
Electronics is an essential tool that can unlock the true potential of modern Silicon Photonic technologies, overcoming their limitations. My thesis contributes to the field of electronic-photonic integration, studying and improving the innovative CLIPP detector and developing the electronics to use it in novel scientific applications.
Silicon Photonic technologies can achieve outstanding datarates, low losses, and power consumption, but require the closed-loop control of the optical devices, to compensate for their extreme sensitivity to fabrication tolerances and temperature fluctuations. The large-scale implementation of feedback control systems is halted by the inadequate state-of-the-art photo-detectors, that introduce losses to monitor the working point of the photonic circuits. The CLIPP, ContactLess Integrated Photonic Probe, is an innovative detector developed at Politecnico di Milano that overcomes these limitations by enabling non-invasive light monitoring in silicon photonic circuits, through an impedance measurement of the waveguide.
My thesis explores the disruptive applications in Silicon Photonics that an innovative device like the CLIPP has unlocked. The work has mastered the electronic detection of the signal coming from the CLIPP, designing specific circuit implementations, in both standard discrete electronics and integrated CMOS technology. In order to improve the tiny signals available when measuring very low optical powers, this thesis has also addressed the sensor itself by demonstrating that more efficient designs can be achieved by exploiting the deep implantations at the same level of the waveguide, offered by active Silicon Photonics technologies. The new design achieved the best sensitivity ever measured with CLIPPs, while giving an insight into new aspects of the device to be studied in the future.
The effectiveness of CLIPP-assisted circuit control was exploited for light path tracking, reconfiguration, and thermal crosstalk compensation on a switch fabric router, and for light mode unscrambling on a novel topology for Mode-Division Multiplexing, that requires non-invasive monitoring to avoid disrupting the orthogonality of the spatial modes. The results would not have been possible without advanced control strategies implemented on a reconfigurable FPGAbased electronic platform specifically conceived for Silicon Photonic applications.