Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, 48109, USA.
School of Electrical and Computer Engineering, Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA.
Adv Mater. 2017 May;29(19). doi: 10.1002/adma.201605177. Epub 2017 Mar 20.
The field of nanophotonics has ushered in a new paradigm of light manipulation by enabling deep subdiffraction confinement assisted by metallic nanostructures. However, a key limitation which has stunted a full development of high-performance nanophotonic devices is the typical large losses associated with the constituent metals. Although silver has long been known as the highest quality plasmonic material for visible and near infrared applications, its usage has been limited due to practical issues of continuous thin film formation, stability, adhesion, and surface roughness. Recently, a solution is proposed to the above issues by doping a proper amount of aluminum during silver deposition. In this work, the potential of doped silver for nanophotonic applications is presented by demonstrating several high-performance key nanophotonic devices. First, long-range surface plasmon polariton waveguides show propagation distances of a few centimeters. Second, hyperbolic metamaterials consisting of ultrathin Al-doped Ag films are attained having a homogeneous and low-loss response, and supporting a broad range of high-k modes. Finally, transparent conductors based on Al-doped Ag possess both a high and flat transmittance over the visible and near-IR range.
纳米光子学领域通过金属纳米结构辅助的深亚波长限制，实现了光的操控的新范例。然而，一个关键的限制因素阻碍了高性能纳米光子器件的全面发展，这就是与组成金属相关的典型的大损耗。尽管银长期以来一直被认为是可见光和近红外应用中最高质量的等离子体材料，但由于连续薄膜形成、稳定性、附着力和表面粗糙度等实际问题，其应用受到限制。最近，通过在银沉积过程中掺杂适量的铝，提出了一个解决上述问题的方案。在这项工作中，通过演示几种高性能关键纳米光子器件，展示了掺杂银在纳米光子学应用中的潜力。首先，长程表面等离激元波导显示出几厘米的传播距离。其次，由超薄掺铝银膜组成的双曲超材料具有均匀的低损耗响应，支持宽范围的高介电常数模式。最后，基于掺铝银的透明导体在可见光和近红外范围内具有高且平坦的透过率。
