Compact optical resonator with enhancement features

A photonics structure, comprising:

• a first ring optical waveguide on a substrate;
• a first rail optical waveguide configured to couple a first light into the first ring optical waveguide;
• first enhancement features configured around the first ring optical waveguide and the first rail optical waveguide;
• a second ring optical waveguide on the substrate;
• a second rail optical waveguide configured to couple a second light into the second ring optical waveguide;
• and
• second enhancement features configured around the second ring optical waveguide and the second rail optical waveguide, wherein
• the first ring optical waveguide, the first rail optical waveguide and the first enhancement features are positioned at a first level over the substrate,
• the second ring optical waveguide, the second rail optical waveguide and the second enhancement features are positioned at a second level over the substrate, and
• the second level is different from the first level, wherein the first and second enhancement features each include an optical waveguide to suppress optical radiation loss from corresponding one of the first and second ring optical waveguide and the first and second rail optical waveguide.

A photonics structure, comprising:

• a first optical ring resonator on a substrate at a first level, wherein the first optical ring resonator further includes a first ring optical waveguide, a first rail optical waveguide configured to couple a first light into the first ring optical waveguide, and first enhancement features configured around the first ring optical waveguide and the first rail optical waveguide;
• a second optical ring resonator on the substrate at a second level, wherein the second optical ring resonator further includes a second ring optical waveguide, a second rail optical waveguide configured to couple a second light into the second ring optical waveguide, and second enhancement features configured around the second ring optical waveguide and the second rail optical waveguide;
• and
• a third optical ring resonator on the substrate at a third level, wherein the third optical ring resonator further includes a third ring optical waveguide, a third rail optical waveguide configured to couple a third light into the third ring optical waveguide, and third enhancement features configured around the third ring optical waveguide and the third rail optical waveguide, wherein
• the first, second and third levels are different from each other,
• the first, second and third ring optical waveguides are vertically aligned,
• the first, second and third enhancement features each include an optical waveguide to suppress optical radiation loss from corresponding one of the first, second and third ring optical waveguides and the first, second and third rail optical waveguide, and
• the first, second and third enhancement features have a width less than that of the first, second, and third ring optical waveguides.