Color-changeable properties of plasmonic waveguides based on Se-doped CdS nanoribbons

The color-changeable optical property induced by the resonance of surface-plasmon polaritons (SPPs) based on a ternary alloy ${\text{CdS}}_{0.65}{\text{Se}}_{0.35}$ (CdSSe) nanoribbon partly placed on an Ag film was reported. The spectroscopic redshift of in situ CdSSe photoluminescence under different incident laser powers was characterized by using scanning near-field optical microscopy. The propagation length, mode area, and confinement factor of the SPPs were also investigated. The trade-off between the spectroscopic shift and plasmonic resonance was demonstrated with the Franz-Keldysh effect and simulated by using the finite-difference time-domain method. The suggested plasmonic structure provides valuable information for the implementation of photonic integrated nanocircuits, especially for the color-changeable plasmonic device.

Figure 1

(a) SEM and TEM (inset) images for the CdSSe nanoribbon. (b) Schematic of the experimental setup and process.

Figure 2

Cross-sectional view of the CdSSe nanoribbon based DLSPP waveguide under investigation.

Figure 3

(Color online) The procedure of the PMMA-mediated nanotransfer printing technique (Ref. 15).

Figure 4

(Color online) The optical transmission image for the CdSSe nanoribbon partly placing on the Ag film. [(a)–(c)] The sequence of dark-field PL spots corresponding to positions 1 and 2, under 12 mW, 40 mW, and 92 mW laser illumination, respectively. Dashed lines indicate the location of the CdSSe nanoribbon.

Figure 5

(Color online) (a) In situ near-field PL spectra of CdSSe nanoribbon for both positions 1 and 2 under various incident laser powers. (b) The plot of redshift value with respect to the excitation laser for both CdSSe and CdS nanoribbons at positions 1 and 2, respectively.

Figure 6

(Color online) (a) The simulation model for a CdSSe nanoribbon deposited on a Ag film. (b) Steady-state image of the simulated electric field at the interface between the Ag film and the nanoribbon. (c) A cross section of the electric field distribution of the CdSSe nanoribbon inside region. (d) Intensity distribution along the nanoribbon center.

Figure 7

(Color online) Confinement factor calculated by using EIM method for several CdSSe nanoribbon thicknesses as a function of nanoribbon width. Vertical crosses indicate the cutoff width.

Figure 8

(Color online) The band structure of a quantum well without and with an applied static electric field. With external electric field, the quadrate well (barrier) potential turns to be triangular well (barrier) potential, and results in a narrowed gap.

Figure 9

(Color online) (a) Spectra of the CdSSe nanoribbon for calculations with the Franz-Keldysh effect. (b) Plots for the comparison between experiments and calculations of redshift values of Se-doped and undoped CdS nanoribbons under the condition of the nanoribbon placed on the Ag film (position 1).