# Counter-directional polariton coupler

## TL;DR

This paper introduces an on-chip counter-directional polariton coupler that controls signal routing using a photonic microdisk potential, demonstrating fast dynamics and potential for scalable non-linear photonic circuits.

## Contribution

It presents a novel on-chip counter-directional polariton coupler with integrated resonant tunnel diode functionality and ultrafast dynamic characterization.

## Key findings

- Demonstrated reversible propagation direction control of polariton condensates.
- Showcased the device's ultrafast response via ps-resolved streak camera measurements.
- Validated the potential for scalable, all-directional polaritonic photonic architectures.

## Abstract

We report on an on-chip routing device for propagating condensates of exciton-polaritons. This counterdirectional coupler implements signal control by a photonic microdisk potential, which couples two lithographically defined waveguides and reverses the condensate's propagation direction. By varying the structural sizes, we utilize the conjunction of the different dimensionalities to additionally evidence the functionality of a polaritonic resonant tunnel diode. Furthermore, we investigate the ultra fast dynamics of the device via ps-resolved streak camera measurements, which is distinctive for the polariton platform. This scalable, all-directional coupler element is a central building block for compact non-linear on-chip photonic architectures.