Chi(3) VIS/NIR nonlinear optics in silicon-based waveguide circuits

Research Area: Integrated nonlinear optics , Photonic integrated circuits for the visible/near IR , Silicon photonics for lab-on-chip spectroscopy

Main Researcher: Haolan Zhao

Silicon photonics leverages the well-developed CMOS fabrication infrastructure for the realization of photonic integrated circuits. This includes devices implemented on silicon-on-insulator and SiN-based circuits. Applications in the visible and near-infrared require the use of SiN waveguide structures, which can be complemented with the integration of high performance silicon-based photodetectors. This enables many applications in the biomedical field in the therapeutic window around 780nm.

Raman Spectroscopy. The figure is reprinted from Wikipedia.

Coherent Anti-Stokes Raman spectroscopy is such an application that allows a sensitive and high throughput analysis of a biological sample of interest. CARS requires either a supercontinuum source or two synchronized short pulse sources of which one is tunable in wavelength. This can be realized using nonlinear optics on a SiN platform and forms the baseline for this work. Given the relatively low nonlinear parameter of SiN the heterogeneous integration of other materials is pursued to enhance the efficiency.

CARS image of a brain slice. The figure is a reprint from [1].

[1] Y. Fu, T. Huff, H. Wang, J. Cheng, and H. Wang, "Ex vivo and in vivo imaging of myelin fibers in mouse brain by coherent anti-Stokes Raman scattering microscopy," Opt. Express 16, 19396-19409 (2008).

Other people involved:

• Francois Leo
• Haolan Zhao
• Roel Baets
• Bart Kuyken

PhD thesises