Design and Characterization of Q-Enhanced Silicon Nitride Racetrack Micro-Resonators

Asymmetric Concentric Microring Resonator Label-Free Biosensors

“…On the other hand, the effect of radiation losses due to the waveguide curvature becomes more pronounced and, consequently, the bent radii have to be increased in relation to those of silicon integrated circuits in order to obtain low losses and sharp resonances. In [7][8][9], the use of asymmetric coupled waveguides for the reduction of radiation losses in curved structures and its application to the enhancement of the intrinsic Q-factor of racetrack micro-resonators was studied in depth. These guiding geometries have been proven particularly useful for the reduction of the footprint of silicon nitride devices.…”

“…Biosensors based on concentric microresonators in the symmetric case were analyzed in [13][14][15]. Whereas the coupled-resonator model is necessary for describing the operation of nonconcentric rings [16,17], the modal method used in [8][9][10][11] provides a more direct approach in concentric arrangements. This technique provides a very large degree of accuracy, necessary in the design of devices to be incorporated in fabricated photonic chips [9,11], at a low computational cost.…”

“…Whereas the coupled-resonator model is necessary for describing the operation of nonconcentric rings [16,17], the modal method used in [8][9][10][11] provides a more direct approach in concentric arrangements. This technique provides a very large degree of accuracy, necessary in the design of devices to be incorporated in fabricated photonic chips [9,11], at a low computational cost. These combined features permit the optimization of more general asymmetric structures not previously addressed.…”

“…In this work, we present a thorough analysis of the properties of optical biosensors built using asymmetric concentric double-ring structures. Following our previous works on racetrack microresonators [7][8][9], we seek to exploit the radiation-quenching properties of the exterior waveguide leading to solutions clearly distinct from those of symmetric structures. The mechanism employed is based on the impact of an asymmetric coupled waveguide on the mode field distribution of a curved dielectric channel.…”

“…In these cases, the exterior waveguide acts as an efficient shielding against the effects of radiation. It is noteworthy that the best-case solutions rest in broad regions in the optimization parameter plane where performance variations are smooth, resulting in designs that are resilient against fabrication tolerances [9][10][11].…”