6533b7d7fe1ef96bd12694f5

RESEARCH PRODUCT

Nonlinear phase shift measurement by heterodyne detection in waveguides optics

subject

description

Nonlinear optics has been a productive field of research and investigation for a few decades now, but the rapid progression of photonic integration platforms in recent years has opened up a whole new range of applications. On-chip integration of effective saturable absorbers and secondary sources including Brillouin laser, supercontinua, or frequency combs are few examples of the very wide possibilities offered by nonlinear nanophotonics. In this context, materials with large third-order optical nonlinearities become highly sought after, as they enable the development of nonlinear functionalities at low input powers. Given a large number of potential candidates as material for nonlinear nanophotonics, it becomes even more important to be able to measure their nonlinear optical response.The two most common techniques for measuring the optical nonlinearity of materials are the Z-scan and four wave mixing (FWM) techniques. The Z-scan method can only be applied to bulk materials, and not to optical waveguides such as the ones used in nanophotonics. In contrast, FWM can measure nonlinearities in waveguides but requires a phase matching, waveguides with low losses and high optical power.This thesis report an interferometric technique relied on heterodyne detection to measure the Kerr index of nonlinear materials. The different stages of the technique implementation have been presented as well as the data processing method. We applied this technique to nonlinear materials of different compositions such as silicon nitride, chalcogenides and silicon-on-insulator. The heterodyne interferometer is not only suitable for integrated waveguides but also for fibers and microfibers. This method has the advantage of being highly sensitive, and is therefore well-adapted to short waveguides or lossy materials. Such a tool would be useful to control nonlinearity and of great help in the development of new materials for integrated photonics.