Generating polarized amplified spontaneous emission at high symmetry points of square lattices

Plasmonic lattices offer a promising platform for overcoming the optical diffraction limit and suppressing radiative losses, which are crucial for advancing large-scale integration in nanophotonic devices. The performance of such integrated devices are strongly influenced by the arrangement and unit geometry of plasmonic lattices, highlighting the need for precise and scalable fabrication strategies. Here, we systematically design and fabricate a series of plasmonic square lattices with decreasing unit symmetries, from C_∞v (O-hole) to C_4v (X-hole) and C_s (OX-hole). The polarization-resolved emission intensities at high symmetry points are thoroughly investigated, revealing a 45° deflection in the polarization angle at Γ⁽¹⁾ as the structural symmetry decreased, while the other four high symmetry points, X⁽¹⁾, M⁽¹⁾, Γ⁽²⁾, and X⁽²⁾, exhibited a 90° polarization shift. This tunability provides an effective approach for modulating the polarization characteristics of plasmonic lattices. The highest polarization degree of 0.59 was observed at the X⁽²⁾ point, where the energy matched the 720 nm emission of the Nile Red gain medium, resulting in directional and polarized amplified spontaneous emission under 532 nm optical pumping. This study establishes a framework for generating polarized amplified spontaneous emission at high symmetry points in plasmonic lattices, providing innovative strategies for tunable light sources in sensing and photonics communication applications.