# Enhanced nonreciprocal transmission through a saturable cubic-quintic nonlinear dimer defect

## TL;DR

This paper investigates how a saturable cubic-quintic nonlinear defect can enable nonreciprocal, diode-like transmission in coupled linear chains, with analytical and numerical analysis revealing high transmission regions and the effects of saturation.

## Contribution

It introduces a detailed analysis of nonreciprocal transmission through a saturable nonlinear defect, highlighting conditions for diode-like behavior and spectral transmission enhancement.

## Key findings

- High transmission regions identified in the spectrum.
- Enhanced diode-like transmission achieved.
- Analytical and numerical methods confirm nonreciprocal behavior.

## Abstract

The transmission properties through a saturable cubic-quintic nonlinear defect attached to lateral linear chains is investigated. Particular attention is directed to the possible non-reciprocal diode-like transmission when the parity-symmetry of the defect is broken. Distinct cases of parity breaking are considered including asymmetric linear and nonlinear responses. The spectrum of the transmission coefficient is analytically computed and the influence of the degree of saturation analyzed in detail. The transmission of Gaussian wave-packets is also numerically investigated. Our results unveil that spectral regions with high transmission and enhanced diode-like operation can be achieved.