Crosstalk Reduction between Closely Spaced Optical Waveguides by Using Higher-Order Modes

Abstract

Optical waveguide structures can make the state-of-the-art micro- and nanofabricated devices faster and less energy consuming. However, on-chip optical components must be placed at relatively large distances from each other, on the order of the wavelength $\ensuremath{\lambda}$, to eliminate the crosstalk between them. This makes on-chip optical structures too large to compete with their electronic counterparts. In this work, we explore the possibility of suppressing the crosstalk between closely spaced dielectric waveguides by making use of higher-order modes. We show that the crosstalk between two waveguides can be essentially eliminated, even if the waveguides are separated by a distance of $\ensuremath{\lambda}/10$ only. We also study arrays of more than two waveguides and find the conditions for the efficient crosstalk reduction in them. Our results can lead to further miniaturization of photonic integrated circuits.