Complementary and Asymmetric Tapered Bent Mid-Infrared Waveguide Arrays for Subwavelength-Pitch Integration and Crosstalk Minimization

TL;DR

This paper introduces a novel mid-infrared waveguide array design using asymmetric tapered Euler-shaped bends, achieving subwavelength integration and crosstalk reduction below 30 dB across 3.1-3.6 microns, enhancing optical phased array performance.

Contribution

It presents the first MIR waveguide array with complementary asymmetric tapered bends, improving fabrication flexibility and crosstalk suppression compared to previous constant-width designs.

Findings

Crosstalk below 30 dB for first and second neighbors across 500 nm range

Maintains performance despite fabrication width variations

Simulations show negligible coupling and low insertion loss

Abstract

This paper delivers the first report of a mid-infrared (MIR) waveguide array design that employs complementary and asymmetric tapered Euler-shaped bends. These provide greater fabrication flexibility to achieve subwavelength-pitch integration while reducing crosstalk to below 30 dB across the 3.1 to 3.6 micron wavelength range. Unlike previous designs, which maintained constant waveguide widths, the Euler waveguide bends are characterized by asymmetric and complementary tapered waveguide widths. This approach significantly reduces crosstalk to below 30 dB for both the first and second neighboring waveguides across a 500 nm wavelength range, enhancing the efficiency of optical phased arrays (OPA) with a large field of view, optimizing light propagation and minimizing crosstalk. The waveguide array is fabricated on a silicon-on-insulator platform, with a 2-micron buried oxide layer and a 500 nm-thick silicon layer. The design is highly tolerant to fabrication variations, maintaining consistent performance even with width variations. The spectral responses, simulated using the 3D finite-difference time-domain method, demonstrate negligible coupling and low insertion loss across the wavelength range. This work offers a robust and CMOS-compatible solution for MIR integrated photonic circuits.