Electrical tunability due to coalescence of exceptional points in parity-time symmetric waveguides

TL;DR

This paper theoretically explores how electrical tuning of PT-symmetric waveguides with imperfect conductive layers can control optical properties by coalescing exceptional points, enabling fast modulation of signals.

Contribution

It introduces a novel method for electrical tunability in PT-symmetric waveguides via exceptional point coalescence influenced by boundary conductive layers.

Findings

Multiple exceptional points can be achieved in the system.

Oblique transmittance and reflectance can be tuned from zero to one.

Electrical gating enables fast optical signal modulation.

Abstract

We demonstrate theoretically the electric tunability due to coalescence of exceptional points in PT-symmetric waveguides bounded by imperfect conductive layers. Owing to the competition effect of multimode interaction, multiple exceptional points and PT phase transitions could be attained in such a simple system and their occurrences are strongly dependent on the boundary conductive layers. When the conductive layers become very thin, it is found that the oblique transmittance and reflectance of the same system can be tuned between zero and one by a small change in carrier density. The results may provide an effective method for fast tuning and modulation of optical signals through electrical gating.