Thesis Cork Institute of Technology, 2019.

Bibliography: (pages 163-173)

The aim of this thesis is to investigate the dynamics of two kinds of swept source lasers for optical coherence tomography. A mathematical model consisting of a pair of coupled delay differential equations was adapted to study Fourier Domain Mode-Locked (FDML) lasers and short cavity swept source lasers, and to explain experimental observations of these lasers. The short cavity laser is experimentally observed to produce pulses during the frequency sweep. This 'sliding frequency mode-locking' behaviour is reproduced by simulation, which is then used to establish simple relationships between the key parameters of sweep speed, linewidth and output power. The FDML laser exhibits a sweep direction asymmetry in both experiment and simulation. this asymmetry also occurs during very slow filter tuning. The similarity between these regimes is established through the model. The instabilities of continuous wave (CW) solutions are calculated in the case of slow filter tuning and used to explain the FDML sweep asymmetry. A method for simulating only a small part of each long FDML frequency sweep was developed. These simulations were used to reproduce experimental observations of convective solitons at the transition from CW to chaotic dynamics - (author's abstract)