Online PhD defence by Yi Zheng

Title: Nonlinear Integrated 4H-SiC-on-Insulator Platform


Principal supervisor: Assoc. Prof. Haiyan Ou, DTU Fotonik, Denmark
Co-supervisor: Senior researcher Minhao Pu, DTU Fotonik, Denmark
Co-supervisor: Senior researcher Hao Hu, DTU Fotonik, Denmark

Evaluation Board
Chairman: Prof. Karsten Rottwitt, DTU Fotonik, Denmark
Researcher Marcin Zielinski, NOVASIC S.A., France
Assoc. Prof. Martijn Heck, Aarhus University, Denmark

Master of the Ceremony
Prof. Leif K. Oxenløwe, DTU Fotonik, Denmark


Nonlinear optics is a rather old field of research, however, the move towards the integrated photonics makes an important turning point. The investigation of nonlinear optical effect in integrated optics leads to a new specific research field, i.e. nonlinear integrated photonics. Benefiting from reinforcement of light-matter interactions in small mode volume of integrated devices, numerous nonlinear optical effect is of great interest to researchers. There is rapid progression of integrated photonic platforms in past two decades based on tremendous efforts made by researchers in the community to develop the science and technology. Pioneering work has been done to develop different nonlinear integrated platforms,all of which have their unique properties and restrictions. Silicon carbide (SiC), primarily utilized for electronic applications currently, is also considered to be the material for nonlinear optics as it holds attractive linear and nonlinear optical properties. In this thesis, we successfully develop an integrated platform called silicon carbideon-insulator (SiCOI) for nonlinear photonics. The main effort has been spent on the technology development for SiC device fabrication and manufacturing of low-loss devices. With well-developed fabrication processes, low-loss waveguides and high quality (Q) factor microring resonators with sub-micron dimension are demonstrated. It is the record value when it was reported, even though there is great improvement of this material very recently and an order of magnitude higher Q device was made. Optical nonlinearities of the developed SiCOI platform are also investigated in this thesis. Compared to the state-of-art results, the four-wave mixing (FWM) in microring resonators shows two orders of magnitude larger conversion efficiency at the same pump power level and the nonlinear parameter is two times higher than the FWM in the waveguide gives broadband conversion, which can be potentially used in nonlinear optical signal processing. Moreover, supercontinuum generation (SCG) shows potential in applications where the broadband sources are critical. From the fundamental research point of view, the exploration of nonlinear integrated SiCOI platform in this thesis is valuable and it also helps to understand the potential and limitations of SiC in this field.

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Wed 29 Apr 20
13:30 - 16:30


DTU Fotonik