Fig. 1. Schematic and projection views of a whispering-gallery-mode oval microdisk. (a) Schematic view of a whispering-gallery-mode oval microdisk and a symmetric elliptical microdisk with a notch; (b)—(d) projections of notch on xy, xz, and yz plane, respectively

Fig. 2. Far-field profiles of an oval microdisk under different deformation parameters ε₂ of the left elliptical microdisk

Fig. 3. Output spectrum. (a) First-order whispering-gallery-mode near-field profile of an oval microdisk; (b) near-filed profile of cross section along dotted line in Fig. (a); (c) output spectral response curve of oval microdisk (inset is enlarged view of strongest resonance peak in dotted rectangle); (d) output spectral response curves of around the highest resonance peak under different notch sizes (inset is high-order WGM resonance peak)

Fig. 4. Comparison of far-field divergence angle of oval microdisk and symmetric elliptical microdisk. (a) Polar plots of far-field divergence angle of oval microdisk and symmetric elliptical microdisk; (b) far-field pattern of unidirectional emission of oval microdisk; (c) enlarged view of dotted rectangle in far-field divergence angle; (d) enlarged view of rectangle in Fig. 4(b)

Fig. 5. Output spectral response curves of ovoid microsphere structure. (a) Schematic view of ovoid microsphere structure; (b) polar plots of far-field divergence angle; (c) enlarged view of far-field divergence angle; (d) enlarged view of strongest resonance peak in dotted rectangle; (e) far-field pattern of unidirectional emission

Fig. 6. Relationship between resonance wavelengths and unidirectional emission efficiencies of three structures