Ultrathin niobium nanofilms on fiber optical tapers – a new route towards low-loss hybrid plasmonic modes

Abstract

Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have recently gained substantial attention in plasmonics, e.g. as building blocks of metasurfaces. Typically, noble metals such as silver or gold are the materials of choice, due to their excellent optical properties, however they also possess some intrinsic disadvantages. Here, we introduce niobium nanofilms (~10 nm thickness) as an alternate plasmonic platform. We demonstrate functionality by depositing a niobium nanofilm on a plasmonic fiber taper, and observe a dielectric-loaded niobium surface-plasmon excitation for the first time, with a modal attenuation of only 3–4 dB/mm in aqueous environment and a refractive index sensitivity up to 15 μm/RIU if the analyte index exceeds 1.42. We show that the niobium nanofilm possesses bulk optical properties, is continuous, homogenous, and inert against any environmental influence, thus possessing several superior properties compared to noble metal nanofilms. These results demonstrate that ultrathin niobium nanofilms can serve as a new platform for biomedical diagnostics, superconducting photonics, ultrathin metasurfaces or new types of optoelectronic devices.

Resonance‐Induced Dispersion Tuning for Tailoring Nonsolitonic Radiation via Nanofilms in Exposed Core Fibers

“…The SCG tuning concept represents a tuning approach that can principally be applied to any waveguide structure with a free standing core, for instance including planar ridge waveguides [ 45 ] or fiber optical tapers. [ 26 ] The achieved DW tuning bandwidth of 298 nm exceeds those of other post‐fabrication tuning scheme for a fixed pump wavelength in the near infrared employing changing either temperature or pressure (140 [ 19 ] and 60 nm, [ 22 ] respectively). To improve bandwidth and uniformity of the generated spectra further coupling efficiencies have to be increased or the laser needs to be replaced in order to obtain higher in‐fiber peak power and thus to excite higher order solitons and enable soliton fission.…”

Correlation between Crystal Structure, Surface/Interface Microstructure, and Electrical Properties of Nanocrystalline Niobium Thin Films

“…In addition, Nb has been widely employed in microelectronics and optoelectronics owing to excellent electronic, thermal, and mechanical qualities. Thin films of Nb have become very appealing to the scientific community as a result of their numerous technological use such as nano-SQUIDs [ 12 , 13 , 14 ] circuits for switches operating at high frequency in cryogenic conditions [ 15 ], superconductivity [ 16 , 17 ], single photon detectors [ 18 ], and high temperature plasmonic applications [ 19 , 20 , 21 ]. Furthermore, recently, Nb based structural alloys have the focus of intense research in view of the possibility to design unique high-entropy alloys for application in energy and aerospace applications.…”

Size effect for achieving high mechanical performance body-centered cubic metals and alloys

“…The size effects on the elasticity and plasticity of facecentered cubic (FCC) materials, which are the most frequently used materials in micro-and nano-technology, have been extensively investigated [22][23][24][25][26]29,[32][33][34][35][36]40,41] and comprehensively reviewed [3,4,[42][43][44][45]. Recently, body-centered cubic (BCC) metals have triggered increasing interest for their broad applications [46][47][48][49][50][51]. However, there has been no systematic review on the size effect on their plasticity.…”