Achieving Cryogenic Temperature in Laser Cooling Using Ion-Doped Nanopowders

摘要国家科学基金项目编号cts -0553651项目负责人Kaviany， massoud附属密歇根大学项目标题：利用离子掺杂纳米粉末实现激光冷却中的低温固体激光冷却是通过介质发射比吸收波长短的光来实现的，多余的能量由晶格声子的湮灭提供。这项技术有潜力开发出一种全固态制冷机，适用于各种应用，如传感器冷却。迄今为止，固体已经从室温冷却到208k（温差T = 92K）。我们建议使用纳米粉末来提高冷却性能，达到T = 170 K。通过(a)通过优化掺杂剂浓度来增加参与电子的居群，(b)通过纳米粉末中的光子局域化来增加相互作用体积中的光子数量，以及(c)通过利用纳米颗粒尺寸效应优化声子态密度来增加参与声子的数量来增加吸收。这种增强的激光冷却性能将通过理论、计算和实验研究来证明。据我们所知，这将是激光冷却纳米结构固体的第一次尝试，也是激光冷却性能首次达到低温范围。就更广泛的影响而言，纳米技术的出现增加了工程研究和教育的科学内容。这个提议的项目是PI持续和系统努力的一部分，该努力将更多的物理基础知识纳入热传递的综合和当前的学术研究教育计划。

ABSTRACTNational Science FoundationProposal Number CTS-0553651Principal Investigator Kaviany, MassoudAffiliation University of MichiganProposal Title Achieving Cryogenic Temperature in Laser Cooling Using Ion-Doped NanopowdersLaser cooling of solid is achieved as the medium emits light at a shorter wavelength than that it absorbs, with the excess energy provided by the annihilation of lattice phonons. This technique has the potential to develop an all solid-state cryocooler for a variety of applications such as sensor cooling. To date, solids have been cooled from room temperature to 208 K (temperature difference T = 92K). We propose to enhance the cooling performance using nanopowders, to T = 170 K. Absorption is increased by (a) increasing the population of participating electrons through dopant concentration optimization, (b) increasing the number of photons in the interacting volume by photon localization in nanopowders, and (c) increasing the number of participating phonons by phonon density of states optimization using nanoparticle size effect. This enhanced laser cooling performance will be demonstrated by a combined theoretical, computational and experimental investigation. To our knowledge, this will be the first attempt of laser cooling in nanostructured solids, and the first time to bring laser cooling performance to cryogenic temperature range. With respect to Broader Impacts, the emergence of nanotechnology has increased the science content of the engineering research and education. This proposed project is part of the PI's continuous and systematic effort to include more physical fundamentals into an integrated and current academic research-education program in heat transfer.