Wide-Field Polarimetric Second-Harmonic Imaging for Rapid and Nondestructive Investigation of Laser-Induced Crystallization Phenomena

Wide-Field Polarimetric Second-Harmonic Imaging for Rapid and Nondestructive Investigation of Laser-Induced Crystallization Phenomena Seonwoo Lee,* Tetsuo Kishi, and Yves Bellouard Cite This: ACS Nano 2024, 18, 24929−24940 Read Online ACCESS Metrics & More Article Recommendations * sı Supporting Information ABSTRACT: The selective and controlled formation of nano- crystals in glass is emerging as a versatile method to achieve functional photonics, optoelectronics, and quantum devices, such as single-photon emitters. Here, we investigate the use of wide-field polarimetric second-harmonic (SH) microscopy as a method to rapidly and nondestructively examine nanoscale crystal arrangements in laser-processed glass. As a case study, we investigate tellurite glass, where the formation of a trigonal tellurium (t-Te) nanocrystalline phase after femtosecond laser exposure was recently demonstrated. Combined with theoretical models, we show that wide-field polarimetric SH microscopy offers comprehensive information on the nanocrystals’ orientation, distribution, and chirality. With its high imaging throughput and spatial resolution, this method has the potential not only to significantly accelerate investigations on laser- induced glass crystallization processes but also to provide a valuable tool for in situ process monitoring. KEYWORDS: wide-field polarimetric second-harmonic microscopy, laser-induced crystallization, nanocrystal-in-glass composites, crystallographic morphologies, chirality INTRODUCTION Taking roots from ancient, millennia-old experimental chemistry where nanocrystals
in these times not known as such
were mixed in glass to achieve certain colors and artistic effects, nanocrystals embedded in a glass matrix are nowadays emerging as a key technology in the next generation of photonic devices such as liquid crystal displays, light-emitting diodes, lasers, and luminescent solar concentrators.1,2 In this context, femtosecond (fs) laser-induced crystalliza- tion in glass has received extensive attention recently due to the intrinsic flexibility of the process, allowing for the formation of arbitrary patterns and/or for in-volume nano- crystallization.3−10 Peak power density of focused fs laser can reach up to TW cm−2, which triggers nonlinear absorption. As this absorption occurs only within the focal volume, the production of crystalline phases can be spatially selective. Using these unique characteristics of fs laser processing, studies have shown the direct writing of electrically conductive channels (e.g., metallization in tellurite-based glass) and the formation of optically active elements (e.g., lithium nio- bate).7,11−13 However, analyzing these crystal nanostructures remains cumbersome due to the small scale of the laser-induced modifications, and it requires destructive investigation means such as transmission electron microscopy (TEM) and associated techniques.10,14,15 Finding an in situ nondestructive method to rapidly extract crystal information, as diverse as orientation, location, and distribution, would be highly beneficial not only to accelerate investigations in laser-induced nanocrystallization processes but also to implement in situ monitoring and closed-loop control strategies. Toward this goal, nondestructive analysis methods, such as Raman7,16−19 or Fourier-transform infrared (FTIR) spectros- copy,20−23 have been proposed. However, these methods are not ideal for in-line measurements, as they are either too slow Received: April 26, 2024 Revised: July 28, 2024 Accepted: August 14, 2024 Published: August 23, 2024 Article www.acsnano.org © 2024 The Authors. Published by American Chemical Society 24929 https://doi.org/10.1021/acsnano.4c05554 ACS Nano 2024, 18, 24929−24940 This article is licensed under CC-BY 4.0