On-chip spectrometer : design, fabrication and experiment

Abstract

This doctorate thesis focuses on the design, fabrication and experimental characterization of novel on-chip spectrometers based on the photonic integrated circuits platform. Specifically, two different types of on-chip spectrometer have been demonstrated. Fabrication processes based on nano-silicon-photonic fabrication (NSP) technology are developed. The first part reports a pre-dispersed spectrometer with both high resolution (0.1 nm) and large spectral range (27 nm) using thermally tunable microring resonator (MRR) array. The second part of the thesis focuses on a microring resonator-assisted Fourier-transform (RAFT) spectrometer, achieving high resolution (0.47 nm) and large bandwidth (90 nm). The models of MRR and MZI thermal modulation exploiting thermo-optic (TO) effect are built and theoretically analysed. The third part of the thesis focuses on the development of core technology of the NSP fabrication processes, including waveguide structures, titanium nitride (TiN) heaters, thermal isolation trenches, and a waveguide-coupled Ge-on-SOI photodetector (PD).