Radiation in bent asymmetric coupled waveguides

Abstract

A numerical study of the radiation in coupled bent waveguides is presented. Such arrangements of curved waveguides in reduced radiation-loss configurations can be used to enhance the quality factor of integrated micro-resonators. 3D full vector computations of the complex modal fields (and propagation constants) and the transient propagation effects have been performed. The results obtained agree qualitatively with former 2D FDTD analyses. At the same time, the calculations presented meet the accuracy requirements for the design of practical implementations that are unattainable with 2D approaches.

Ultracompact integrated polarizers using bent asymmetric coupled waveguides

“…In this work, a new all-dielectric polarizer architecture is proposed. It is based on bent coupled waveguides [19,20]. These structures, originally 1 proposed for the reduction of the radiation loss in improved-Q resonators, can perform strong differential losses for TE/TM polarizations.…”

“…These structures, originally 1 proposed for the reduction of the radiation loss in improved-Q resonators, can perform strong differential losses for TE/TM polarizations. We will consider the geometries of previous works [19,20] based on the assumption of deep etched Si 3 N 4 rectangular waveguide with a SiO 2 cladding and a center operation wavelength of λ = 1.55 µm. The width of transmission waveguides is w = 1 µm and all the waveguides have a height of h = 300 nm.…”

“…1 (right). An in-depth analysis of modal properties of curved asymmetric coupled waveguides used in our polarizers has been presented in [20]. The study is based on intensive 3D full-vector numerical computations and has permitted to identify the modes that remain predominantly confined in the transmission (inner) waveguide.…”

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.…”