Polycrystalline materials can mediate efficient frequency up-conversion for mid-infrared light. Motivated by the need to understand the properties of the harmonic and supercontinuum radiation from such media, we utilize realistic numerical simulations to reveal its complex temporal and spatial structure. We show that the generated radiation propagates in the form of long-duration pulse trains that can be difficult to compress and that optical filamentation in high-energy pulses gives rise to fine-structured beam profiles. We identify trends concerning pulse energy, sample length, and the microstructure of the material that can inform optimization for different applications.
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http://dx.doi.org/10.1364/OE.418198 | DOI Listing |
Adv Sci (Weinh)
November 2024
Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore.
Thermal radiation management is of critical importance in energy, sensing, and heat transfer. According to Planck's law, objects at room temperature predominantly emit thermal radiation within the mid- and far-infrared bands. Here, we demonstrated the upconversion of the mid- and far-infrared thermal radiation emitted by second-order nonlinear material to the easily-detectable visible band through a difference frequency process.
View Article and Find Full Text PDFNat Comput Sci
June 2024
Laboratoire Kastler Brossel, École Normale Supérieure-Paris Sciences et Lettres Research University, Sorbonne Université, Centre National de la Recherche Scientifique, UMR 8552, Collège de France, Paris, France.
Neural networks find widespread use in scientific and technological applications, yet their implementations in conventional computers have encountered bottlenecks due to ever-expanding computational needs. Photonic computing is a promising neuromorphic platform with potential advantages of massive parallelism, ultralow latency and reduced energy consumption but mostly for computing linear operations. Here we demonstrate a large-scale, high-performance nonlinear photonic neural system based on a disordered polycrystalline slab composed of lithium niobate nanocrystals.
View Article and Find Full Text PDFWith the development of laser technology, nonlinear optics plays a crucial role in frequency conversion. However, the generation of second harmonics in nonlinear optical crystals is generally subject to rigorous phase-matching conditions that hinder the performance of broadband tunability. It is believed that introducing disorders in nonlinear optical materials is helpful to overcome this obstacle.
View Article and Find Full Text PDFAdv Mater
June 2024
State Key Laboratory of Luminescent Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640, China.
The development of novel materials and structures for efficient second-order nonlinear micro/nano devices remains a significant challenge. In this study, the remarkable enhancement of second-harmonic generation (SHG) and cascaded sum frequency generation in whispering gallery mode microspheres made of surface-crystallized glass with a 6-µm BaTiSiO crystal layer are demonstrated. Attributed to the core-shell design, the BaTiSiO located on the surface can be efficiently coupled with whispering gallery modes, resulting in a highly efficient micron-scale cavity-enhanced second-order optical nonlinearity.
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