Ultrafast Spectroscopy of Plasmonic Titanium Nitride Nanoparticle Lattices

Abstract

Titanium nitride (TiN) is an advantageous plasmonic material for optoelectronic applications that require resilience to extreme irradiation or temperatures. Although TiN is optically similar to noble metals at near-infrared wavelengths under steady-state excitation conditions, their photoexcited properties are distinct at ultrafast time scales. This paper describes the differences in optical properties between coupled TiN nanoparticles in 2D arrays that support surface lattice resonances (SLRs) and TiN nanoparticle arrays that support only localized surface plasmons (LSPs). Compared to symmetric photoinduced peak broadening in the LSPs, we found that SLRs show asymmetric broadening at ps-time scales in transient absorption measurements. Furthermore, TiN nanoparticle arrays were robust and withstood pump fluences exceeding 50 mJ/cm2 for over half an hour with little to no change in bleach wavelength.