Strong Coupling of Intersubband Resonance in a High Electron Mobility Transistor Structure to a THz Metamaterial by Ultrawide Electrical Tuning

TL;DR

This paper demonstrates strong coupling between THz metamaterial resonances and intersubband resonances in a high electron mobility transistor, achieved through ultrawide electrical tuning enabled by a triangular quantum well.

Contribution

It introduces a method for electrically tuning intersubband resonances over a wide range using a triangular potential in a high electron mobility transistor structure, enabling strong coupling with metamaterials.

Findings

Achieved a coupling strength of 0.52 THz.

Demonstrated ultrawide electrical tuning of ISR.

Observed transition from uncoupled to strongly coupled regime.

Abstract

The interaction between intersubband resonances (ISRs) and metamaterial microcavities can form a strongly coupled system where new resonances form that depend on the coupling strength. Here we present experimental evidence of strong coupling between the cavity resonance of a THz metamaterial and the ISR in a high electron mobility transistor structure with a triangular confinement. The device is electrically switched from an uncoupled to a strongly coupled regime by tuning the ISR with epitaxially grown transparent gates. An asymmetric triangular potential in the heterostructure enables ultrawide electrical tuning of ISR which is an order of magnitude higher as compared to the equivalent square well. For a single triangular well, we achieve a coupling strength of 0.52 THz, with a normalized coupling ratio of 0.26.