Fig. 1. Top view of the structure of a linear waveguide taper. W0 is the width of the single-mode waveguide, Wmax is the maximum taper width, L is the length of the taper, θ is the local half angle of the taper at point z, and θm is the projection of the ray angle of the first-order mode of the taper.

Fig. 2. Transmission dependence on the constant α of the silicon waveguide taper designed using Eq. (2), at a wavelength of 1550 nm.

Fig. 3. Transmission of a taper designed according to Eq. (2) as a function of the length of the taper. For comparison, linear, parabolic, exponential, and Gaussian taper types are included.

Fig. 4. Simulated field intensity |E|2 for the various tapers at a wavelength of 1550 nm. (a) 5-μm-long adiabatic taper designed using Eq. (2), (b) 5-μm-long exponential taper, (c) 5-μm-long parabolic taper, (d) 5-μm-long Gaussian taper, (e) 5-μm-long linear taper, and (f) 15-μm-long linear taper.

Fig. 5. Transmission of the tapers as a function of taper length at a wavelength of 1550 nm. The widths of the input and output waveguides are 12 and 0.5 μm, respectively.

Fig. 6. Transmission of the designed taper for different taper thicknesses as a function of taper length, for the fundamental TE mode at a wavelength of 1550 nm.