Photonic Crystal Surface Emitting Lasers (PCSELs) based on III-V nanostructures

Temu, Balthazar 2025. Photonic Crystal Surface Emitting Lasers (PCSELs) based on III-V nanostructures. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

In recent years Photonic Crystal Surface Emitting Lasers (PCSELs) have been of great interest to many researchers. PCSELs emit light with circular and symmetric beam profile, whose spectrum has narrow linewidth and is stable with temperature. Unlike other semiconductor lasers, PCSELs can maintain single mode operation even when the diameter of lasing area is increased to hundreds of microns, enabling them to emit light with high out power and narrow optical beam divergence. Because of this desirable feature, most of the focus of research in the field has been on increasing the output power/brightness of PCSELs. Although high output power PCSELs are important for various application, low threshold PCSELs are useful to save the energy consumption of these devices. Despite this importance PCSEL research community has not made enough effort to design and fabricate low threshold PCSEL devices. In this PhD thesis the design and fabrication of low threshold PCSELs will be studied both experimentally and through simulations. The thesis will begin by exploring the design, simulation and fabrication of air-hole based PCSELs. Different designs of photonic crystal patterns which can demonstrate low threshold lasing will be considered and simulation results will be presented. The details of fabrication of a low threshold suspended membrane PCSEL and the corresponding optical pumping results will be discussed. The fabrication of the PCSEL at extended wavelength in the C band will be discussed. The airhole based PCSEL cannot be grown on silicon platform without defects. An alternative approach that can solve this problem is deployment of nanowire based PCSEL. The honeycomb nanowire PCSEL has shown promise as a device which can have low lasing where a lasing threshold of 1.25 μJ/cm2 has been demonstrated in the O band. In this thesis the simulation results which can enable the extension of the resonant wavelength of the PCSEL to other wavelengths for different applications will be presented. Furthermore, looking to optimize the lasing threshold of the honeycomb PCSEL to achieve even lower thresholds, simulation results showing improved quality factors of the devices will be given. The confinement factor of the different band edge modes resonant in the device will be explained. The optical pumping results and simulation results of the low threshold nanowire based PCSEL will then be presented. The low threshold obtained by the nanowire based PCSEL is attributed to the quasi bound states in the continuum (BIC) mode in the cavity of the deformed honeycomb lattice, which has very large quality factor. To get even lower lasing threshold the PCSEL using the quantum well in the core-shell structure of the nanowire has been demonstrated. With proper optimization of the photonic crystal design and the nanowire composition the nanowire quantum well device can achieve really low lasing threshold. For the nanowire based PCSEL to be of practical use it needs to be electrically pumped. Simulation of the electrically pumped and the fabrication of the honeycomb pattern of nano holes will be discussed. Although the growth and fabrication of the electrically pumped PCSEL was not completed, the steps to complete them will be discussed with examples from the literature and the completion of the device will be left as part of the future work.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	Photonic crystal surface emitting lasers (PCSELs), Photonic crystal lasers, Nanowire lasers, Low threshold lasers, Quantum well lasing, Nanowire honeycomb PCSELs, Deformed honeycomb lasers, Suspended membrane PCSEL and fabrication of PCSELs
Date of First Compliant Deposit:	5 May 2026
Last Modified:	06 May 2026 09:05
URI:	https://orca.cardiff.ac.uk/id/eprint/186748

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