Phonon polaritons (PhPs), the collective phonon oscillations with hybridized electromagnetic fields, concentrate optical fields in the mid-infrared frequency range that matches the vibrational modes of molecules. The utilization of PhPs holds the promise for chemical sensing tools and polariton-enhanced nanospectroscopy. However, investigations and innovations on PhPs in the aqueous phase remains stagnant, because of the lack of in situ mid-infrared nano-imaging methods in water. Strong infrared absorption from water prohibits optical delivery and detection in the mid-infrared for scattering-type near-field microscopy. Here, we present our solution: the detection of photothermal responses caused by the excitation of PhPs by liquid phase peak force infrared (LiPFIR) microscopy. Characteristic interference fringes of PhPs in 10B isotope-enriched h-BN were measured in the aqueous phase and their dispersion relationship extracted. LiPFIR enables the measurement of mid-infrared PhPs in the fluid phase, opening possibilities, and facilitating the development of mid-IR phonon polaritonics in water.
Probing mesoscopic nonlocal screening in van der Waals heterostructures with polaritons
Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR)（材料研究工程研究所，科学技术研究局）；Quantum Innovation Centre (Q. InC), Agency for Science, Technology and Research (A*STAR)（量子创新中心，科学技术研究局）；School of Materials Science and Engineering, Nanyang Technological University（南洋理工大学材料科学与工程学院）；Department of Materials Science and Engineering, National University of Singapore（新加坡国立大学材料科学与工程系）；National Key Laboratory of Microwave Photonics & College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics（南京航空航天大学微波光子学国家重点实验室与电子信息学院）；School of Electrical and Electronic Engineering, Nanyang Technological University（南洋理工大学电气与电子工程学院）；Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences（中国科学院上海光学精密机械研究所）；Department of Mechanical Engineering, The Hong Kong Polytechnic University（香港理工大学机械工程系）
Probing individual phonon-polaritonic nanoparticle-on-mirror cavities by infrared nanospectroscopy
CIC nanoGUNE BRTA（纳米科学联合中心）；Materials Physics Center, CSIC-UPV/EHU（材料物理中心，西班牙国家研究委员会-巴斯克地区大学）；Department of Physics, University of the Basque Country UPV/EHU（巴斯克地区大学物理系）；Department of Physics, University of Fribourg（弗里堡大学物理系）；Donostia International Physics Center (DIPC)（圣塞巴斯蒂安国际物理中心）；Department of Electricity and Electronics, FCT-ZTF, University of the Basque Country EHU（巴斯克地区大学电气与电子工程系）；IKERBASQUE, Basque Foundation for Science（伊克尔巴斯基奎，巴斯克科学基金会）
Spatiotemporal Electron Microscopy of Phonon Polaritons in MoO3
Technion – Israel Institute of Technology（以色列理工学院）；Bar Ilan University（巴伊兰大学）；ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology（巴塞罗那科学和技术研究所光子科学研究所）；ICREA-Institució Catalana de Recerca i Estudis Avanats（加泰罗尼亚高级研究学院）
Measuring momentum-resolved dissipation of phonon-polaritons in LiNbO$_3$ with terahertz driving
Brigham Young University（杨百翰大学）；ETH Zurich（苏黎世联邦理工学院）；Sapienza University of Rome（罗马第一大学）；Université de Strasbourg（斯特拉斯堡大学）；Université Paris Cité（巴黎西岱大学）；Paul Scherrer Institut（保罗谢尔研究所）
