Yoann Jestin received his PhD (2002) in solid state chemistry from the “Université du Maine” (France) working on a project supported by the French National Network in Research and Telecommunications. His work was related to the design, manufacturing and testing of large numerical aperture fluoride based optical fibers for the realization of an optical amplifier prototype working in the S-band telecommunication window. In 2003 he joined the research center on laser and application at the University of Lille as a postdoctoral student to study and characterize semiconductor quantum dots in amorphous thin films. After this period he joined the CNR-IFN (Trento, Italy) with a grant from the local government of province of Trento, to work on the development of ultra-transparent glass ceramics waveguides for the demonstration of an optical single frequency amplifier in the C-band telecommunication window. In 2009 he worked as a researcher at the Bruno Kessler Foundation (Trento, Italy) to conduct research on the micro-fabrication of nanocrystalline based silicon solar cells. Since 2013 he won a mobility fellowship to visit the INRS-EMT and experiment new materials and structures for integrated nonlinear optics.
Optical spectroscopy, Photonic Band Gap materials, Sol-gel Chemistry, Rare earth spectroscopy, nonlinear optic, optical fibres, planar waveguides, micro resonators, plasmonic, optical sensors, integrated optic, solar cells.
Material Investigation for Laser Amplification (MILA):
One specific objectives is the characterization of SiN and SiON micro-resonators and low loss waveguides previously designed and fabricated at the Micro-fabrication and Technologic Laboratory (MTLab) of the Fondazione Bruno Kessler (FBK). Those two materials or their combination i.e. SiN ring resonators and SiON bus waveguides, are actually tested for their implementation in the FD-FWM laser operating scheme, thus providing a feedback for the simulation of the laser structure and the optimization of the specific waveguides and micro-ring resonators geometry. Furthermore thanks to the good stability of the studied mode-locked laser, frequency combs which are of increasing interest for generation of radio-frequency reference signals, could be envisioned. In the first part of the present study, SiN and SiON thin films with different refractive index using various conditions of PECVD atmosphere with the purpose of obtaining high quality near stoichiometric have been prepared. Different deposition routines have been employed, including variable flow ratio of silane (SiH4) ammonia (NH3) and nitrous oxide (N2O) and deposited on to a silicon substrate. Films have been characterized in term of deposition rate, thickness, refractive index, surface morphology and composition. Waveguides made of SiN and SiON, have then been fabricated by PECVD process. The optimum geometry for light propagation and coupling between the waveguiding structure, and the ring resonators has been determined by simulation tools thus defining the optimum micro-fabrication parameters i.e. deposited thickness, etching depth and waveguide width. In figure 1 is presented the Mode profile at 1550 nm and losses calculation from 1480 to 1550 nm for a SiON waveguide.
A particular attention has been paid to the process control for the minimization of absorption losses and then for successful operation of the devices. The microresonators were characterized in typical waveguide transmission experiments in a broad near-infrared wavelength range between 1350 nm and 1600 nm. Figure 2a shows a series of sharp and broad resonances corresponding to first- (fundamental) and second-order radial mode families of the SiN based resonator. A blow- up of the spectrum around a fundamental mode is shown in the top panel of Figure 2b.