Abstract
We report on evanescently coupled rectangular microresonators with dimensions up to 20 × 10 μm2 in silicon-on-insulator in an add-drop filter configuration. The influence of the geometrical parameters of the device was experimentally characterized and a high Q value of 13,000 was demonstrated as well as the multimode optical resonance characteristics in the drop port. We also show a 95% energy transfer between ports when the device is operated in TM-polarization and determine the full symmetry of the device by using an eight-port configuration, allowing the drop waveguide to be placed on any of its sides, providing a way to filter and route optical signals. We used the FDTD method to analyze the device and e-beam lithography and dry etching techniques for fabrication.
Highlights
Rectangular microcavities in silicon-on-insulator (SOI) have attracted research attention because of their diverse applications ranging from optical filters [1] to refractive index sensors [2] due to their multimode resonant nature
Present the design, fabrication, and characterization of three different sizes of rectangular microresonators in an add-drop filter configuration, as well as in a novel configuration of eight ports and characterization of three different sizes of rectangular microresonators in an add-drop filter to validate the symmetry of the device and show, for the first time to our knowledge, selective mode configuration, as well as in a novel configuration of eight ports to validate the symmetry of the device coupling and a high Q value of 13,000
The following sections focus on this figure on merit by modifying the coupling length and gap for three different sizes of resonator operated in transverse electric (TE) and transverse magnetic (TM) polarization
Summary
Rectangular microcavities in silicon-on-insulator (SOI) have attracted research attention because of their diverse applications ranging from optical filters [1] to refractive index sensors [2] due to their multimode resonant nature. Rectangular resonators are ideal candidates for sensing applications as they maximize the footprint efficiency while providing a significant sensing area in comparison with photonic crystals [11] Another advantage is the relaxation of the fabrication process because precise periods or gaps are not required as in [12]. Their intrinsic resonant characteristics lead to a moderate Q-value of 4000 [13], and several attempts have been made to enhance it by cutting the corners [14] or by using different types of polygons such as triangles [15], hexagons [16,17], octagons [18], and deformed versions of these shapes [19,20].
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