Erlangen 2018 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 39: Poster: Quantum Optics and Photonics II
Q 39.20: Poster
Tuesday, March 6, 2018, 16:15–18:15, Zelt Ost
Improved thermo-optic dispersion formulas from SPDC and nonlinear spectral magnification — •Aron Vanselow and Sven Ramelow — Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
The accurate knowledge of the dispersion properties of nonlinear crystals is vital for many applications in classical and quantum nonlinear optics. Here, we experimentally demonstrate a new method using spontaneous parametric down-conversion (SPDC) to accurately measure thermo-optic dispersion formulas for nonlinear crystals to extend and improve on existing relations.
Our method generates photon pairs via SPDC at birefringently phase-matched signal and idler wavelengths using 3 different pump lasers. Recording the temperature-dependent signal photon spectra using a grating spectrometer then allows for fitting the temperature-dependent dispersion relations for the signal and remarkably also for the undetected idler wavelengths. Specifically, we investigate the ordinary refractive indices no of undoped and 5.0 mol% MgO doped congruent lithium niobate (LN) as well as the principal refractive index of the y-axis, ny, of flux-grown potassium titanyl phosphate (KTP).
The potential error sources of our method are analysed in detail and we demonstrate that even standard spectrometers with uncooled detectors are sufficient, making our new method robust and cost-effective. Finally, we show how our setup and the new dispersion formulas can be useful for nonlinear spectral magnification, which allows for a significant increase in resolution measuring the pump laser spectrum.