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Abstract Key challenges limiting the adoption of metallic plasmonic nanostructures for practical devices include structural stability and the ease of large‐scale fabrication. Overcoming these issues may require novel metamaterial fabrication with potentials for improved durability under extreme conditions. Here, a self‐assembled growth of a hybrid plasmonic metamaterial in thin‐film form is reported, with epitaxial Ag nanopillars embedded in TiN, a mechanically strong and chemically inert matrix. One of the key achievements lies in the successful control of the tilt angle of the Ag nanopillars (from 0° to 50°), which is attributed to the interplay between the growth kinetics and thermodynamics during deposition. Such an anisotropic nature offered by the tilted Ag nanopillars in TiN matrix is crucial for achieving broadband, asymmetric optical selectivity. Optical spectra coupled with numerical simulations demonstrate strong plasmonic resonance, as well as angular selectivity in a broad UV–vis to near‐infrared regime. The nanostructured metamaterials in this work, which consist of highly conductive metallic nanopillars in a durable nitride matrix, have the potential to serve as a novel hybrid material platform for highly tailorable nanoscale metamaterial designs, suitable for high temperature optical applications. 

Abstract Photonic integrated circuits require various optical materials with versatile optical properties and easy on‐chip device integration. To address such needs, a well‐designed nanoscale metal‐oxide metamaterial, that is, plasmonic Au nanoparticles embedded in nonlinear LiNbO₃(LNO) matrix, is demonstrated with tailorable optical response. Specifically, epitaxial and single‐domain LNO thin films with tailored Au nanoparticle morphologies (i.e., various nanoparticle sizes and densities), are grown by a pulsed laser deposition method. The optical measurement presents obvious surface plasmon resonance and dramatically varied complex dielectric function because of the embedded Au nanoparticles, and its response can be well tailored by varying the size and density of Au nanoparticles. An optical waveguide structure based on the thin film stacks of a‐Si on SiO₂/Au‐LNO is fabricated and exhibits low optical dispersion with an optimized evanescent field staying in the LNO‐Au active layer. The hybrid Au‐LNO metamaterial thin films provide a novel platform for tunable optical materials and their future on‐chip integrations in photonic‐based integrated circuits.