Anti-reflection subwavelength gratings for InP-based waveguide facets

We demonstrate the anti-reflection properties of litho-graphically defined subwavelength gratings applied to the facets of integrated waveguides realized in the InP membrane-on-silicon platform. The subwavelength gratings are based on the gradient index effect to create a smooth index transition between the core material and air, making it possible to obtain reflections below -30 dB at a wavelength of 1550 nm for both TE and TM polarized modes, as shown by 3D finite-difference time-domain simulations. Characterizations performed using Mach-Zehnder interferometers as test structures show relative reflections as low as -25 dB, confirming the effectiveness of the technique. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

The study demonstrates the anti-reflection properties of lithographically defined subwavelength gratings applied to integrated waveguides on the InP membrane-on-silicon platform. The use of gradient index effect creates a smooth index transition between core material and air, achieving reflections below -30 dB at a wavelength of 1550 nm. Experimental results show that relative reflections as low as -25 dB can be achieved using Mach-Zehnder interferometers as test structures.