Alignment-tolerant broadband compact taper for low-loss coupling to a silicon-on-insulator photonic wire waveguide

Abstract

We experimentally demonstrate a broadband, fabrication tolerant compact silicon waveguide taper (34.2 µm) in silicon-on-insulator. The taper works on multi-mode interference along the length of the taper. A single taper design has a broadband operation with coupling efficiency >70% over 700 nm that can be used in O, C and L-band. The compact taper is highly tolerant to fabrication variations; ±100 nm change in the taper and end waveguide width varies the taper transmission by <5%. The footprint of the device i.e. taper along with the linear gratings is ~ 442 m 2 ; 11.5X smaller than the adiabatic taper. The taper with linear gratings provides comparable coupling efficiency as standardly used focusing gratings. We have also compared the translational and rotational alignment tolerance of the focusing grating with the linear grating.

Compact simply-connected SOI spot size converters for TE and TM polarizations

“…These methods can effectively reduce the device length while maintaining the mode order, but they require more complex fabrication processes due to the sub-wavelength or graded-index structures. Moreover, researchers have also proposed methods to implement SSCs using mode transformations, such as sinusoidal tapers [24,25], segmented stepwise taper [26] and segmented curvature taper [27].…”