Beating absorption in solid-state high harmonics

Autor: Siddharth Buddhiraju, Yu Shi, Jingyuan Linda Zhang, Philip H. Bucksbaum, Giulio Vampa, Shanhui Fan, Hanzhe Liu, David A. Reis, Jelena Vuckovic
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Communications Physics, Vol 3, Iss 1, Pp 1-6 (2020)
ISSN: 2399-3650
Popis: Since the new millennium coherent extreme ultra-violet and soft x-ray radiation has revolutionized the understanding of dynamical physical, chemical and biological systems at the electron’s natural timescale. Unfortunately, coherent laser-based upconversion of infrared photons to vacuum-ultraviolet and soft x-ray high-order harmonics in gaseous, liquid and solid targets is notoriously inefficient. In dense nonlinear media, the limiting factor is strong re-absorption of the generated high-energy photons. Here we overcome this limitation by generating high-order harmonics from a periodic array of thin one-dimensional crystalline silicon ridge waveguides. Adding vacuum gaps between the ridges avoids the high absorption loss of the bulk and results in a ~ 100-fold increase of the extraction depth. As the grating period is varied, each high harmonic shows a different and marked modulation, indicating their waveguiding in the vacuum slots with reduced absorption. Looking ahead, our results enable bright on-chip coherent short-wavelength sources and may extend the usable spectral range of traditional nonlinear crystals to their absorption windows. Potential applications include on-chip chemically-sensitive spectro-nanoscopy. Control of nonlinear optical processes at the nanoscale is vital for the generation of on-chip short-wavelength sources, yet strong re-absorption of this radiation limits its efficiency in solids. Here, high harmonics are generated in an array of 1D silicon ridge waveguides, mitigating bulk re-absorption.
Databáze: OpenAIRE
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