Light guided in tailored environments: from basic aspects to applications (Ph.D. thesis)

TL;DR

This thesis investigates quantum optical effects involving single photons in tailored structures, combining theoretical, numerical, and experimental analyses to advance understanding and modeling of photon behavior in complex environments.

Contribution

It provides new methods for estimating crystal parameters, numerical models for photon pair generation, and insights into waveguide modes with applications in quantum optics.

Findings

Accurate estimation of Sellmeier coefficients in nonlinear crystals.

Numerical modeling of photon pair wavefunctions aligns with experimental data.

Analysis of bent waveguide modes reveals quantum particle analogies.

Abstract

This dissertation is dedicated to investigating quantum optical effects involving single photons in tailored structures. It consists of six chapters and an appendix. The central part of the thesis starts with a chapter titled "Theoretical background" where the author introduces key quantum optical concepts needed for understanding the subsequent chapters. The next chapter is devoted to a discussion of the estimation of the Sellmeier coefficient in nonlinear crystals with the SPDC process. The accuracy and feasibility of the method are analysed in the context of the experimental results. The subsequent chapter is focused on the numerical modelling of the photon pair wavefunction generated in the SPDC process. In this chapter, the author presented a comparison between numerically predicted outcomes with the experimental results obtained in two different laboratory setups. The fifth chapter is devoted to modelling the modes of the bent waveguide, combining analytical considerations and numerical modelling. The correctness of the results is verified with numerical simulations obtained in COMSOL. In this chapter author emphasized the context of basic research: It is shown that the bent waveguide is described by equations analogous to the equations of the dynamics of a quantum particle in a space with axial symmetry. The appendix is devoted to the form of the differential operator in cylindrical coordinates, the analysis of the influence of photon propagation in the optical fibre on the photon wave function and the Schr\"odinger equation for a particle in two-dimensional space with axial symmetry.