Abstract
Optical microdisk cavities with certain asymmetric shapes are known to possess unidirectional far-field emission properties. Here, we investigate arrays of these dielectric microresonators with respect to their emission properties resulting from the coherent behaviour of the coupled constituents. This approach is inspired by electronic mesoscopic physics where the additional interference effects are known to enhance the properties of the individual system. As an example we study the linear arrangement of nominally identical Lima\c{c}on-shaped cavities and find mostly an increase of the portion of directional emitted light while its angular spread is largely diminished from 20 degrees for the single cavity to about 3 degrees for a linear array of 10 Lima\c{c}on resonators, in fair agreement with a simple array model. Moreover, by varying the inter-cavity distance we observe windows of reversion of the emission directionality and super-directionality that can be interesting for applications. We introduce a generalized array factor model that takes the coupling into account.
Highlights
Optical microdisk cavities have become a target of intense study because of their versatile properties to control light and their unique application potential [1] as high-Q resonators [2], microlasers [3,4], and sensors [5,6]
This approach is inspired by electronic mesoscopic physics where the additional interference effects are known to enhance the properties of the individual system
They play an important role as widely accessible experimental realizations of theoretical model systems [7] used in quantum chaos [8,9,10,11] and mesoscopic physics [12]
Summary
Optical microdisk cavities have become a target of intense study because of their versatile properties to control light and their unique application potential [1] as high-Q resonators [2], microlasers [3,4], and sensors [5,6] They play an important role as widely accessible experimental realizations of theoretical model systems [7] used in quantum chaos [8,9,10,11] and mesoscopic physics [12]. Our naive expectation and motivation is the possibility of an enhancement of directional emission properties inherent to single deformed optical microdisk cavities, e.g., of the Limaçon shape [14]. To this end, we investigate a linear array (chain) of Limaçon resonators. Since the excitation pulse in each resonator has a finite spectral width that is slightly broader than the spectral splitting of the array modes for the not too small (and experimentally relevant) d/R values considered here, we observe an excitation close to the symmetric array mode with intensity distributions close to that of the single cavity, cf. Supplemental Material [24], and dedicate the following discussion to this case
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