on the September 30, 2025
Séminaire: 15h15
Non linear crystals: from their study for frequency conversion to their use in devices
Abstract:
We are interested in the spontaneous interaction of coherent light with a nonlinear crystal in order to achieve frequency conversion. We have studied sum-frequency generation (SFG), including second-harmonic generation (SHG), as well as difference-frequency generation (DFG). All these will be described for non-specialists using quantum pictures, and the main associated parameters will be identified using waves picture.
I will present our unique experimental approach, which provides direct access to the angular distribution of optical properties, and subsequently to the recording of the parameters associated with frequency conversion. I will focus on phase-matching conditions that lead to the most efficient conversion efficiency. We use one bulk crystal shaped as a sphere polished to optical quality. It is rotated while being combined with a tunable commercial source propagating along its diameter. We have studied nonlinear crystals grown by leading research groups within the ultraviolet to far infrared transparency range.
I will also report our work using nonlinear crystals, which are shaped like cylinders, for a new design of optical parametric oscillators (OPOs).