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arXiv · 1206.2426

Cavity QED treatment of scattering-induced efficient free-space excitation and collection in high-Q whispering-gallery microcavities

Yong-Chun Liu·Yun-Feng Xiao·Xue-Feng Jiang·Bei-Bei Li·Yan Li·Qihuang Gong
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Abstract

Whispering-gallery microcavity laser possesses ultralow threshold, whereas convenient free-space optical excitation and collection suffer from low efficiencies due to its rotational symmetry. Here we analytically study a three-dimensional microsphere coupled to a nano-sized scatterer in the framework of quantum optics. It is found that the scatterer is capable of coupling light in and out of the whispering-gallery modes (WGMs) without seriously degrading their high-Q properties, while the microsphere itself plays the role of a lens to focus the input beam on the scatterer and vice versa. Our analytical results show that (1) the high-Q WGMs can be excited in free space, and (2) over 50% of the microcavity laser emission can be collected within less than ${1}^{\circ}$. This coupling system holds great potential for low threshold microlasers free of external couplers.

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Yong-Chun Liu, Yun-Feng Xiao, Xue-Feng Jiang, Bei-Bei Li, Yan Li, Qihuang Gong. 2012-06-12. Cavity QED treatment of scattering-induced efficient free-space excitation and collection in high-Q whispering-gallery microcavities. https://doi.org/10.1103/physreva.85.013843

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