Fig. 1. Layout of the vertical two-channel OADM based on the SRM, which is composed of an SRM with a parabolic lobe-like pattern along the axial direction, a 180° silicon waveguide bend, and a silicon straight waveguides in two vertical aligned substrates.

Fig. 2. Effective index of the optical modes in 215.5-nm-thick silicon waveguide for different widths at λ=1.55  μm.

Fig. 3. (a) A top view of the 180° waveguide bend with a lateral offset. (b) 180° bending loss of a silicon waveguide as a function of the lateral offset. The width and thickness of the waveguide are 400 and 215.5 nm, respectively. The bend radius is 4.5 μm.

Fig. 4. (a) Non-scaled cross section of the free-standing part of the SRM, showing the inner edge, the outer edge, and the asymmetric parameter. (b) The resonant wavelength of the TiO2 SRM as a function of the asymmetric parameter for the 65th azimuthal mode and the first radial mode. The design parameters are: SRM radius=8  μm, winding number=3, and bilayer thickness=115  nm.

Fig. 5. Cross section of the two-channel OADM in the x–z plane at γ=87.7°, which is composed of a free-standing part of a TiO2 SRM coupled to the two straight waveguides embedded in two vertically aligned substrates.

Fig. 6. Transmittance coefficient in the drop port as a function of the gap between the SRM and silicon waveguides.

Fig. 7. Transmission spectra of the drop ports of the OADM when it serves as an optical demultiplexer.

Fig. 8. Transmission spectra of “adds to drops” when it serves as an optical multiplexer.