Abstract

We report on a sapphire-fiber-based lens that can be used to enhance the emitted THz power of a large-area photoconductive antenna (PCA). Using numerical simulations, we demonstrate that the lens provides a spatial redistribution of the photocarriers density in the PCA’s gap. By optimizing the diameter of the sapphire-fiber, one could reach efficient confinement of the photocarriers in the vicinity of the PCA electrodes with a 10-$\mathrm{\mu}$m gap size for a 220-$\mathrm{\mu}$m-thick sapphire-fiber. This allows enhancing the coupling of the incident electromagnetic waves at the interface between the sapphire fiber and the semiconductor with the antenna terminals by ∼40 times for a single PCA element, as well as boosting the total efficiency of the large-area PCA-emitter up to ∼7–10 times. To validate our approach, we propose a step-by-step process that can be used for the precise and controllable placement of the sapphire-fiber on the surface of a single PCA.

© 2022 Optica Publishing Group

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