Terahertz pulse generation with binary phase control in non-linear InAs metasurface

TL;DR

This paper presents a novel non-linear InAs metasurface that generates and structures terahertz pulses at the source, enabling advanced beam control for spectroscopy and imaging.

Contribution

It introduces a nanoscale InAs metasurface platform for simultaneous THz pulse generation and beam structuring, with binary phase control capabilities.

Findings

THz pulses generated via optical rectification in InAs metasurfaces are more efficient than in ZnTe.

The metasurface allows control over pulse polarity and amplitude.

Demonstrated a metalens that generates and focuses THz pulses.

Abstract

The effect of terahertz (THz) pulse generation has revolutionized broadband coherent spectroscopy and imaging at THz frequencies. However, THz pulses typically lack spatial structure, whereas structured beams are becoming essential for advanced spectroscopy applications. Non-linear optical metasurfaces with nanoscale THz emitters can provide a solution by defining the beam structure at the generation stage. We develop a non-linear InAs metasurface consisting of nanoscale optical resonators for simultaneous generation and structuring of THz beams. We find that THz pulse generation in the resonators is governed by optical rectification. It is more efficient than in ZnTe crystals, and it allows us to control the pulse polarity and amplitude, offering a platform for realizing binary-phase THz metasurfaces. To illustrate this capability, we demonstrate an InAs metalens, which simultaneously generates and focuses THz pulses. The control of spatiotemporal structure using nanoscale emitters opens doors for THz beam engineering and advanced spectroscopy and imaging applications.