# Active Tuning of Surface Phonon Polariton Resonances via Carrier Photoinjection

## TL;DR

This paper demonstrates active tuning of surface phonon polariton resonances in semiconductor nanoresonators using carrier photoinjection, enabling dynamic control of infrared nanophotonic devices with high tuning efficiency.

## Contribution

It introduces a novel method of tuning SPhP resonances via carrier photoinjection in InP and 4H-SiC, achieving state-of-the-art tuning performance and rapid recovery times.

## Key findings

- Achieved significant blue-shift of SPhP resonances through carrier injection.
- Demonstrated continuous-wave and pulsed excitation tuning with high figures of merit.
- Observed rapid tuning recovery in 4H-SiC due to carrier redistribution.

## Abstract

Surface-phonon polaritons (SPhPs) are attractive alternatives to far-infrared plasmonics for sub-diffractional confinement of light. Localized SPhP resonances in semiconductor nanoresonators are very narrow, but that linewidth and the limited extent of the Reststrahlen band inherently limit spectral coverage. To address this limitation, we report active tuning of SPhP resonances in InP and 4H-SiC by photoinjecting free carriers into the nanoresonators, taking advantage of the coupling between the carrier plasma and optical phonons to blue-shift SPhP resonances. We demonstrate state-of-the-art tuning figures of merit upon continuous-wave (CW) excitation (in InP) or pulsed excitation (in 4H-SiC). Lifetime effects cause the tuning to saturate in InP, and carrier-redistribution leads to rapid (<50 ps) recovery of the tuning in 4H-SiC. This work opens the path toward actively tuned nanophotonic devices, such as modulators and beacons, in the infrared and identifies important implications of coupling between electronic and photonic excitations.

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Source: https://tomesphere.com/paper/1705.05980