Supporting information
Soft plasmons with stretchable spectroscopic response
based on thermally patterned gold nanoparticles
Xinping Zhang*, Jian Zhang, Hongmei Liu, Xueqiong Su, and Li Wang
Institute of Information Photonics Technology and College of Applied Sciences,
Beijing University of Technology, Beijing 100124, P. R. China
*Email: zhangxinping@bjut.edu.cn
Figures S1 (a) and (b) shows the scanning electron microscope images of the grating
structures fabrication using solution-processed method for an annealing temperature
below 200 oC and above 350 oC, respectively. At a lower annealing temperature than
200 oC, although the ligands have been sublimated completely, the gold nanoparticles
get molten to aggregate into larger ones that cannot become molten anymore. Thus,
the strong confinement mechanisms based on molten gold cannot take effect at such a
low annealing temperature. As results, gold nanoparticles are distributed around the
grating grooves without forming homogeneous gold nanolines, as shown in Fig. S1(a).
However, when the annealing temperature is increased further to above 350 oC, the
gold nanoparticles are melted completely, and the molten gold is pulled into the
grooves by the strong surface tension, as shown in Fig. S1(b).
Fig. S1 SEM images of the MPC structures annealed at a temperature lower than 200 oC (a) and
above 350 oC (b).
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Supporting information
Figure S2 (a) and (b) shows the optical extinction spectroscopic measurements on the
transferred MPCs on PDMS substrates before the coating of the PMMA waveguide
layer for TM and TE polarizations, respectively. Thus, Fig. S2 shows the
angle-resolved tuning performance of the optical extinction spectra of MPCs on a bare
PDMS substrate, where the incident angle is increased from 0 to 30 degrees. Plasmon
resonance without Fano coupling is observed for TM polarization in Fig. S2(a), which
is centered around 666 nm. No obvious plasmon resonance is observed for TE
polarization, as shown in Fig. S2(b).
Fig. S2 Optical extinction spectra at different incident angles (0~30o)measured on the MPCs
directly transferred to the PDMS substrates before deposition of the PMMA waveguide layer for
(a) TM and (b) TE polarization. The transmission spectrum through a bare PDMS plate is used as
the blank in the optical extinction calculation.
Figure S3 shows results of the stretching experiment by optical extinction spectra of
MPCs on PDMS substrates at an incident angle of (a) i=0 and (b) i=6o, where the
stretching amount of PDMS substrate were increased from =0 to =1000 mm. The
Fano resonance, which results from the coupling between the waveguide resonance
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Supporting information
and plasmon resonance modes and is recognized by a narrow-band dip in the optical
extinction spectrum, shifts to the red with increasing the stretching amount. This
red-shift process is indicated and guided by the red arrows in Fig. S3(a) and (b). In the
measurement results in Fig. S3, the transmission spectrum through a bare PDMS plate
is used as the blank in the optical extinction calculation.
Fig. S3 Optical extinction spectra at (a) i=0 and (b) i=6o for different stretching amounts
(=0~1000 m). The transmission spectrum through a bare PDMS plate is used as the blank in the
optical extinction calculation.
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