Lasing at the band edges of plasmonic lattices

Abstract

We report room temperature lasing in two-dimensional diffractive lattices of silver and gold plasmon particle arrays embedded in a dye-doped polymer that acts both as waveguide and gain medium. As compared to conventional dielectric distributed feedback lasers, a central question is how the underlying band structure from which lasing emerges is modified by both the much stronger scattering and the disadvantageous loss of metal. We use spectrally resolved back-focal plane imaging to measure the wavelength-and angle dependence of emission below and above threshold, thereby mapping the band structure. We find that for silver particles, the band structure is strongly modified compared to dielectric reference DFB lasers, since the strong scattering gives large stop gaps. In contrast, gold particles scatter weakly and absorb strongly, so that thresholds are higher, but the band structure is not strongly modified. The experimental findings are supported by finite element and fourier modal method calculations of the single particle scattering strength and lattice extinction.

Plasmonic surface lattice resonances in arrays of metallic nanoparticle dimers

“…it does not radiate. However, it might perhaps be important in applications of dimer arrays to lasing structures [50,51].…”

Plasmonic phase-gradient metasurface for spontaneous emission control

“…A detailed description of the used setup is given by Schokker et al in Ref. [21]. Figure 4 shows a schematic of the microscope as configured for "back focal plane" imaging.…”

“…Figure 1(b) shows a SEM micrograph of a phase-gradient antenna array fabricated with electron beam lithography in a positive resist (ZEP520) on a glass cover slide with the conditions given in Ref. [21]. Exposure was done using dot exposure with doses of (1-1.5) × 10 −4 pC using an electron gun voltage of 20 kV and a current of 0.11 nA.…”

“…We choose the geometry recently studied by Rodriguez et al [9,19] and by Schokker et al [21], which consists of antennas residing on a glass substrate (Menzel Gläser, n glass = 1.52) covered in a 400-nm-thick layer of a high-index polymer (SU8). Due to its high refractive index (n SU8 = 1.65), the photoresist acts as a single mode slab waveguide.…”

“…In our paper we made use of the fact that a planar waveguide, that is only just sufficiently thin to be single mode, has good overlap with the particles, and also of the fact that the slow 1/ √ r field decay in a waveguide ensures many unit cells are significantly polarized [21,38]. Similar asymmetries can occur in other planar waveguiding systems that abide by the same rules, such as slots in Au or Ag films, provided the slots have an engineered phase and amplitude response [39].…”