Amplification of high harmonics in 3D semiconductor waveguides

TL;DR

This paper demonstrates nanoscale amplification of high harmonic generation in 3D semiconductor waveguides, enabling efficient high-energy conversion with minimal laser energy input.

Contribution

It introduces a novel nano-structured semiconductor waveguide design that significantly amplifies high harmonics without melting issues seen in metallic structures.

Findings

Achieved 6 orders of magnitude larger amplification volume.

Observed harmonic amplification factor of 30.

Demonstrated efficient coupling of nano-joule laser energy.

Abstract

Nanoscale amplification of non-linear processes in solid-state devices opens novel applications in nano-electronics, nano-medicine or high energy conversion for example. Coupling few nano-joules laser energy at a nanometer scale for strong field physics is demonstrated. We report enhancement of high harmonic generation in nano-structured semiconductors using nanoscale amplification of a mid-infrared laser in the sample rather than using large laser amplifier systems. Field amplification is achieved through light confinement in nano-structured semiconductor 3D waveguides. The high harmonic nano-converter consists of an array of zinc-oxide nanocones. They exhibit a large amplification volume, 6 orders of magnitude larger than previously reported and avoid melting observed in metallic plasmonic structures. The amplification of high harmonics is observed by coupling only 5-10 nano-joules of a 3.2 {\mu}m high repetition-rate OPCPA laser at the entrance of each nanocone. Harmonic amplification (factor 30) depends on the laser energy input, wavelength and nanocone geometry.