Realizing high-quality, ultra-large momentum states using semiconductor hyperbolic metamaterials

TL;DR

This paper compares semiconductor and metallic hyperbolic metamaterials, showing that semiconductor variants can achieve ultra-large momentum states and ultrafast topological transitions using optical pumping, especially at mid-infrared frequencies.

Contribution

It demonstrates that semiconductor hyperbolic metamaterials can reach very high photon momentum states and enable ultrafast topological transitions, expanding the potential applications of hyperbolic metamaterials.

Findings

SHMs operate within the effective medium limit at mid-infrared frequencies.

SHMs can attain ultra-large photon momentum states.

Ultrafast topological transitions are possible via optical pumping.

Abstract

We employ both the effective medium approximation (EMA) and Bloch theory to compare the dispersion properties of semiconductor hyperbolic metamaterials (SHMs) at mid-infrared frequencies and metallic hyperbolic metamaterials (MHMs) at visible frequencies. This analysis reveals the conditions under which the EMA can be safely applied for both MHMs and SHMs. We find that the combination of precise nanoscale layering and the longer infrared operating wavelengths puts the SHMs well within the effective medium limit and, in contrast to MHMs, allows the attainment of very high photon momentum states. In addition, SHMs allow for new phenomena such as ultrafast creation of the hyperbolic manifold through optical pumping. In particular, we examine the possibility of achieving ultrafast topological transitions through optical pumping which can photo-dope appropriately designed quantum wells on the femtosecond time scale.