Date of Award
Open Access Dissertation
Doctor of Philosophy in Applied Physics (PhD)
Administrative Home Department
Department of Physics
Committee Member 1
Committee Member 2
Jae Yong Suh
Committee Member 3
In this thesis, quantum inspired symmetries including Parity-Time (PT) symmetry and Supersymmetry (SUSY) have been studied in the context of non-Hermitian engineered laser systems. This thesis starts with a short review of semiconductor lasers theory in second chapter, followed by an introduction to quantum inspired symmetries: PT symmetry and SUSY in optics and photonics in chapter three.
In chapter four, we have studied the robustness and mode selectivity in PT symmetric lasers. We investigate two important aspects of PT symmetric photonic molecule lasers, namely the robustness of their single longitudinal mode operation against instabilities triggered by spectral hole burning effects, and the possibility of more versatile mode selectivity. Our results, supported by numerically integrating the nonlinear rate equations and performing linear stability analysis, reveals the following: (1) In principle a second threshold exists after which single mode operation becomes unstable, signaling multimode oscillatory dynamics, (2) For a wide range of design parameters, single mode operation of PT lasers having relatively large free spectral range (FSR) can be robust even at higher gain values, (3) PT symmetric photonic molecule lasers are more robust than their counterpart structures made of single microresonators; and (4) Extending the concept of single longitudinal mode operation based on PT symmetry in millimeter long edge emitting lasers having smaller FSR can be challenging due to instabilities induced by nonlinear modal interactions. Finally, we also present a possible strategy based on loss engineering to achieve more control over the mode selectivity by suppressing the mode that has the highest gain (i.e. lies under the peak of the gain spectrum curve) and switch the lasing action to another mode.
In chapter five a new scheme for building two dimensional laser arrays that operate in the single supermode regime is proposed. This is done by introducing an optical coupling between the laser array and a lossy pseudo-isospectral chain of photonic resonators. The spectrum of this discrete reservoir is tailored to suppress all the supermodes of the main array except the fundamental one. This spectral engineering is facilitated by employing the Householder transformation in conjunction with discrete supersymmetry. The proposed scheme is general and can in principle be used in different platforms such as VCSEL arrays and photonic crystal laser arrays.
Finally, in chapter six we have investigated the laser self-termination (LST) in trimer photonic molecules. It is shown that under the appropriate conditions, LST can exist in complex discrete structures made of three-cavity photonic molecule lasers. We have shown that the phenomenon of LST is a purely linear effect associated with avoided level crossings. Furthermore, our simulations show that the predicted behavior is persistent when gain saturation nonlinearity is taken into account.
Conclusion remarks and future works are discussed in the last chapter.
Teimourpour, Mohammad Hosain, "QUANTUM INSPIRED SYMMETRIES IN LASER ENGINEERING", Open Access Dissertation, Michigan Technological University, 2017.