Optical investigation of materials for future photonic and quantum technologies

Abstract

Three materials with important applications in both present and planned future photonic and quantum devices have been optically characterised. Photoluminescence (PL) measurements have been carried out on ion-beam implanted erbium doped lithium niobate, Er:LiNbO3, including polarisation-sensitive PL spectra, lifetime and mapping measurements across a range of temperatures from 5 to 300 K. The measurements validated our ability to engineer sample areas that are emissive in the fibre-optic compatible wavelength region with nanoscale precision, and without affecting the rest of the sample. From the PL spectra, the Stark splitting of the 4I15/2 state was calculated for the first time for ion-beam implanted Er:LiNbO3. The temperature dependence of the PL characteristics showed an interesting trend, with a local maximum in both emission intensity and lifetime at T ~ 50 K. The reason for this is currently unclear, although hypotheses and directions for future investigation of the issue are discussed. Photon echo experiments, important due to being one of the few ways to calculate the dephasing time, T2, of a material, were carried out on erbium doped yttrium silicate, Er:Y2SiO5. In the absence of a magnetic field and at a temperature of 1.5 K, T2 was found to be 2.08 ± 0.08 µs and its behaviour was investigated as a function of applied magnetic field. PL measurements were also carried out on caesium lead bromide, CsPbBr3, perovskite nanocrystals. CsPbBr3 is an important material for many optoelectronic applications, due to its good emissive properties and the tuneability of its bandgap. PL spectra and lifetime measurements were taken at temperatures ranging from 1.5 to 300 K and at magnetic fields ranging from 0 to 7 T. The data was used to suggest the radiative recombination mechanisms present in CsPbBr3.

Date of Award	30 Oct 2023
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Richard Curry (Main Supervisor) & Jessica Boland (Co Supervisor)