In conclusion, a model was proposed to couple 2D material-based light emitters to a resonant cavity efficiently. The model that was proposed which is based on rod-type PhCs provides advantages over current methods for 2D material-cavity coupling. These advantages include spatial coupling between the field’s maximum and the quantum emitter and improved light collection efficiency from these cavities. The photonic band diagram for the designed structure was solved and the field distribution within an H1 cavity was simulated. Simulations of the collected flux spectra was measured for a range of PhC rod radii and maximum enhancement in the collection efficiency of about 400% was shown for
𝑟 = 0.161𝑎. A series of simulations were carried out to investigate the effect of having the monolayer dipping at different heights inside the cavity. It was shown that maximum enhancement is achieved when the source spatially overlaps with the cavity mode’s maximum and reduces as the source is moved up or down from the cavity due to reduced spatial coupling and coupling to leaky modes outside the cavity, respectively.
Chapter 4 – Photonic Crystals for Coupling to 2D Materials
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Details of the fabrication process of these PhCs were explained and preliminary results were shown. The method of transferring monolayers on the cavity and the results achieved were demonstrated. Enhancing the collection efficiency further could be done using the author’s recent work in Solid Immersion Lenses24,25. Glass SILs can be reliably positioned on top of the cavities with micrometer-
scale accuracy. These kind of SILs were shown to give over 300% enhancement in the light collection efficiency. While SILs made of other materials such as GaAs can achieve over 1000% enhancement as discussed in reference 24. Combining SILs with the PhC cavities can lead to a greater increase in the light collected from TMDC monolayers. Another advantage in placing a SIL on top of the cavity can be enhancing the vertical confinement due to total internal reflection at the air-glass interface. Initial results from FDTD simulations show that adding a slab with a similar refractive index to that of glass showed that the cavity’s Q-factor can be increased by four folds.
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Chapter 5 – Deterministic Positioning of III-V Nanowires on Silicon for Photodetector Applications
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